Jurgen H. Daniel Palo Alto Research Center
Gyoujin Cho Sunchon National University
Thomas Blaudeck Chemnitz University of Technology
Mehmet R. Dokmeci Northeastern University
D1: Roll Processing for Transistors, Sensors and Photovoltaics
Tuesday PM, November 30, 2010
Room 308 (Hynes)
9:30 AM - **D1.1
Materials and Processes for Flexible Electronics.
Howard Wang 1 2 Show Abstract
1 Institute for Materials Research, State University of New York, Binghamton, New York, United States, 2 Center for Advanced Microelectronics Manufacturing, State University of New York, Binghamton, Binghamton, New York, United States
Flexible electronics (FlexE) is emerging as an indispensible force that will drive future electronics applications ranging from displays, lighting and communication to sensing, renewable energy and biomedicine. The major challenge in realizing the FlexE revolution is the development of new materials and new processes that enable roll-to-roll (R2R) processes for manufacturing electronics with desirable performance. Polymeric materials and nanomaterials are among those compatible with solution-based R2R manufacturing processes. Using examples from our recent effort in developing flexible sensor arrays, I will illustrate difficulties and potential benefits in using conjugated polymers and metal nanoparticles in device fabrications. Some undesirable characteristics could be the origin of other favorable traits. For example, for mostly insoluble conjugated polymers, metastable structures formed in solution could be critical in determining their applicability and devices performances. On the other hand, the granular morphology of sintered metal nanoparticles is partly responsible for the extraordinary stretchability of their films on plastic substrates. The opportunity in FlexE manufacturing lies in the intricate balance among many competing factors.
10:00 AM - D1.2
Integration of 57 Transistors on Plastic Foil Using Roll-to-roll Gravure.
Minhun Jung 1 2 , Jinsoo Noh 1 2 , Joonseok Kim 1 2 , Hwiwon Kang 2 , Soyeon Kim 2 , Kwangyong Lee 1 , Kyunghwan Jung 1 2 , Dongsun Yeom 2 , Yongsu Park 1 , Minjin Lee 1 , Gyoujin Cho 1 Show Abstract
1 Printed Electronics Engineering in World Class University Program, and Chemical Engineering, Sunchon National University, Sunchon, Jeonnam, Korea (the Republic of), 2 Printed Electronics Research Institute, Paru Co. , Sunchon, Jeonnam, Korea (the Republic of)
To integrate thin film transistors (TFTs) with roll-to-roll (R2R) gravure printing methods, all printed TFTs should be under acceptable operation ranges of threshold voltage (Vth), on-off ratio, subthreshold swing and transconductance. Those parameters are fluctuated mostly depending on the degree of alignment between gate electrodes and drain-source electrodes. Furthermore, the fine tuning of printed TFTs can be achieved by controlling roughness and waviness of R2R printed dielectrics and drain-source electrodes. Therefore, R2R gravure system first should be evaluated using plastic foils and electronic inks such as silver nanoparticle based inks to prove the attainable best values in OPRA, roughness, line width, waviness and thickness of printed patterns. Based on the previous evaluation on the commercially available R2R gravure system, the attainable best roughness, line width, waviness and thickness of the printed patterns were about respectively 45 nm, 317 µm, ± 3 µm and 600 nm while OPRA could be controlled to ± 40 µm. Under those values, the layout of TFTs should contain the longer channel length (> 200 µm) to minimize the effect of OPRA. Therefore, the channel length of 250 µm was designed to compensate ± 40 µm of OPRA under given R2R gravure system. Due to the very long channel length and huge surface roughness, organic molecular or polymeric active layers would not give a reasonable performance of TFTs at this system. Therefore, single walled carbon nanotube (SWNT) has been employed to use as an active layers since SWNT is less sensitive to the surface roughness and the longer channel length due to its ballistic electronic transport. In this presentation, R2R gravure has been first employed to show a way of integrating 57 transistors for generating 16 bit digital codes on plastics foils using SWNTs as active layers.
10:15 AM - **D1.3
Printed Flexible Electronics: Display and Sensor Applications.
Ana Arias 1 , Tse Nga Ng 1 , Jurgen Daniel 1 , Gregory Whiting 1 , Robert Street 1 , Rene Lujan 1 , Sean Garner 1 , Beverly Russo 1 , Brent Krusor 1 Show Abstract
1 , PARC, Palo Alto, California, United States
The Palo Alto Research Center (PARC) is developing processes for printed and flexible electronics by integrating inorganic and organic materials with flexible substrates. Over the years we have demonstrated flexible active matrix TFT backplanes based on amorphous silicon, poly-silicon and organic semiconductors for emissive and reflective displays. We have also demonstrated devices targeting medical applications such as flexible hybrid image sensors and flexible blast dosimeter (sensor tapes) to detect the occurrence of events that cause traumatic brain injury. The sensor tape design includes integrated sensors, signal conditioning electronics, non-volatile memory and a thin film battery. The electronic circuits are based on jet-printed organic electronics with the emphasis on low-voltage electronics due to the limitations of the battery size. In order to meet the low cost target of the tapes, fabrication techniques such as inkjet printing, laser machining and lamination are employed with all deposition and patterning steps been compatible with future roll-to-roll manufacturing. Our focus is to lower processing temperatures in order to use plastic substrates and introduce direct writing steps to reduce the use of materials and provide a lower cost approach to manufacturing. In this talk, I will highlight the challenges of processing semiconducting materials on flexible substrates and give examples of commercial applications where flexible electronics and displays are desired. I will also discuss the use of inkjet printing as a tool to improve materials performance and prototype flexible sensors and electronics.
10:45 AM - D1.4
Roll-to-roll Manufacture of Pentacene-based Thin Film Transistors with a Flash-evaporated Polymer Dielectric Cured with an E-beam.
Gamal Abbas 1 , Donna Cheng 1 , Kanad Mallik 1 , Hazel Assender 1 Show Abstract
1 Department of Materials, University of Oxford, Oxford United Kingdom
We report our fabrication of pentacene field effect transistors (FETs) based on a vacuum processed and e-beam cured polymer electrolyte (i.e., tripropylene glycol diacrylate (TRPGDA)) as a gate dielectric layer on flexible wide web substrates. The deposition of the semiconductor and gate insulator layers is carried out in Oxford’s roll-to-roll vacuum web processing facility and could be combined in-line with roll-to-roll pattern metallisation. The aim of the work is to demonstrate the ability to create all-evaporated transistors, exploiting the kind of technologies at present extensively used in the food packaging industry, for example, in which all layers can deposited at high web speeds. Our method is room temperature and solvent-free with an ultrahigh deposition rate (web speeds in excess of 100 m/min are possible).The performance of the pentacene and the polymer dielectric materials within devices was investigated, demonstrating (1) the ability to deposit good quality pentacene layers in the roll-to-roll environment and (2) the importance of the e-beam curing conditions of the dielectric layer on the performance of the organic FET devices. This deposition route creates a smooth, pin-hole-free dielectric layer as it is deposited onto the substrate as a monomeric liquid, before curing, and there is no mass-loss such as in solvent-based deposition processes. The tuning of the transistors’ operating voltage and output characteristics was feasible through the ease of control of the polymer dielectric thickness achieving a threshold voltage of only -5V. For example the output and transfer characteristics of a device with good curing of the 0.55 micrometre thick dielectric layer gives threshold voltage = 0.8V, on/off ratio = 1000, and mobility = 0.22cm^2/Vs. This device has a 250 micrometre channel length and an aspect ratio of 16. No SAM or other surface modification had been applied to the insulator layer to achieve these properties.The ability to integrate such a high deposition rate polymer process, into a single step, multilayer, vacuum deposition process with conventional vacuum deposition sources provides a possible route to low cost and large area electronics processing.
11:30 AM - **D1.5
Roll-to-roll Nanomanufacturing Processes and Applications in Organic Solar Cells.
L. Jay Guo 1 Show Abstract
1 EECS, University of Michigan, Ann Arbor, Michigan, United States
Nanoimprint lithography as high precision nanoscale patterning technique has attracted world-wide attention. Developments in this area have enjoyed great momentum in the past decade and numerous applications have been exploited. One of the advantages of this technique is its compatibility with polymeric and organic materials with different functionalities. However, the current process and throughput in Nanoimprinting is still far from meeting the demands of many practical applications, especially in photonics, biotechnology, and organic optoelectronics. To address this issue, we have developed two high-speed nanomanufacturing processes, continuous roll-to-roll Nanoimprinting and Dynamic NanoInscribing. This talk will describe these techniques and the associated material requirement. Applications in organic solar cells will also be discussed. To increase the power conversion efficiency of organic solar cells, nanoimprinting has been used to create ordered nanoscale morphology in conjugated polymer materials, and a new fabrication method scalable to roll-to-roll processing was developed to produce the most optimum bulk heterojunction morphology as compared with other conventional annealing based-methods.
12:00 PM - **D1.6
Polymer Solar Modules: Roll-to-roll Processing and Characterization by Lock-in Thermography and Luminescence Imaging.
Harald Hoppe 1 , Maik Baerenklau 1 , Marco Seeland 1 , Aart Schoonderbeek 2 , Oliver Haupt 2 , Roland Roesch 1 , Uwe Stute 2 , Gerhard Gobsch 1 , Dieter Teckhaus 3 Show Abstract
1 Institute of Physics, Ilmenau University of Technology, Ilmenau Germany, 2 , Laser Zentrum Hannover e.V., Hannover Germany, 3 , SK Kassetten GmbH & Co. KG, Neuenrade Germany
We combine unstructured slot-dye coating as a method for continuous high-throughput large area deposition with laser ablation for the formation of monolithic solar cell interconnects. Laser ablation is especially suitable for minimizing active area losses within the photovoltaic module. By careful modelling of the geometric device parameters according to constraints arising from series and contact resistances, solar module performance gets optimized. An important advantage of this processing technology is its flexibility for production parameter adaptation to exchange of the material system. For quality control and consecutive optimization of the solar modules we apply techniques such as lock-in thermography and luminescence imaging. These methods allow for precise and local observation of shunts and other deficiencies in the device production and yield a direct feedback to the coating and laser ablation parameters. Furthermore we demonstrate electroluminescence to be a versatile tool to access properties of the layer stack with relation to photovoltaic parameters.
12:30 PM - **D1.7
Laser Treatment of Organic Thin Film Solar Cells.
Maurice Clair 1 Show Abstract
1 research and development, 3D-Micromac AG, Chemnitz, Saxony, Germany
One of the most anticipated developments in the area of thin film photovoltaics is the devlopment of new solar cells based on organic conductors and semiconductors – organic photovoltaics (OPV). As the deposition of these so called functional polymers can be realized by high volume production methods, e.g. printing and coating, the price per solar cell can be reduced significantly. In combination with their flexibility organic thin film solar cells can in future be used to enable new applications therewith creating new markets. A typical design of an organic solar cell is based on a flexible substrate, e.g. polyethylene (PET) foil, covered with a transparent conductive oxide (TCO) layer, e.g. indium tin oxide (ITO) as front electrode. A bulk hetero junction consisting of a poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) on top of a Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) is then deposited on the substrate. The solar cell is then finalized by the deposition of a back electrode, either using vacuum or printing processes.Based on such a material system 3D-Micromac AG has performed tests following two different approaches for the use of laser within a possible r2r production line for OPV. The first approach is dealing with the selective ablation of the different layers, especially the functional polymers, using ultra short pulsed laser sources. Such scribing steps have already been introduced in the production of classical silicon bulk solar cells and thin film photovoltaics based on non-organic components. For OPV production using a laser micro machining process instead of a structured deposition process (e.g. gravure printing) for the generation of the required pattern can improve the registration accuracy and in parallel increase the active area of the resulting solar cell as scribing widhts of 20µm can be realized.The second approach is based on the need for a thermal annealing step for the optimization of the bulk hetero junction of the P3HT:PCBM layer. This step is vital for the performance and lifetime of the resulting solar cell, as the amount of remaining solvents is being reduced/minimized and the morphology of the micro phase seperation is adjusted leading to a change in the absorption characteristics of the bulk-hetero junction. Usually the annealing of the layer is realized by using ovens what can take up to several minutes. This has a tremendous impact on the required length of the drying units, especially for later high speed production systems. The principle of introducing energy to the polymer layer by laser radiation may reduce the annealing time significantly. 3D-Micromac AG has so far concentrated its efforts on the pre-annealing step, meaning a thermal treatment of the organic layer before the deposition of the back electrode. Within the talk the up to date results achieved by 3D-Micromac AGs R&D department on both approaches will be presented.
D2: Printing of Components for Flexible Electronic Systems
Tuesday PM, November 30, 2010
Room 308 (Hynes)
2:30 PM - **D2.1
Roll-to-Roll Printed Electronics.
Walter Fix 1 Show Abstract
1 , PolyIC GmbH & co KG, Fürth Germany
The fabrication of roll-to-roll printed electronics allows the mass production of microelectronic products in a cost-efficient way. Soluble semiconducting materials, an adjustment of existing printing processes and an adapted chip design pave the way for new products, such as printed antenna, displays, memories, solar cells and even more complex devices like “radio frequency identification” (RFID) tags. In order to realize roll-to-roll printed electronics several key requirements have to be met. For high volume fabrication a low cost semiconductor material with sufficiently high electrical performance has to be available. In addition high speed printing processes as well as electronic circuit designs have to be adapted to the needs of printed electronics. Last but not least high speed roll-to-roll electrical test equipment has to be developed to ensure high quality. At PolyIC a special layer stack for integrated circuits was designed consisting of a lower metal electrode (e.g. silver) followed by an organic semiconductor like P3AT, a special insulating layer and an upper metal electrode for example based on copper. With this layer stack transistors, diodes, resistors, capacitors and vias can be realized. In this way more than 10000m2 of printed circuits can be fabricated each month at a typical web speed of about 30m/min. Besides a fast roll-to-roll production process a roll-to-roll test capability is of similar importance. A typical roll-to-roll test machine is presented and its working principle will be discussed in detail. Finally several applications are addressed based on our printed PolyIC layer stack. Fast transistors for example need high resolution for source and drain electrodes. Thus, the lower metal layer of our stack can be used to manufacture transparent conductive films consisting of a mesh of 10µm wide metal lines. Such PolyIC films outperform standard ITO and PEDOT films not only in terms of transmittance but also in terms of conductivity which makes them a good choice for applications like touch sensors, EMI shielding or flexible circuit boards.Low cost printed memory cells can be fabricated by replacing the semiconductor and insulator in our four layer stack by a special ferroelectric polymer. The basic principle and possible applications will be addressed.Finally, taking advantage of the full capability of our fabrication process a 4 bit Manchester chip was not only printed but also tested and analyzed with our roll-to-roll manufacturing technique.
3:00 PM - D2.2
Roll-to-roll Gravure Printed Resistive WORM Memory on Flexible Substrate.
Jaakko Leppaniemi 1 , Tomi Mattila 1 , Terho Kololuoma 2 , Ari Alastalo 1 Show Abstract
1 Printed Functional Solutions, Inorganic Devices, VTT Technical Research Centre of Finland, Espoo Finland, 2 Printed Functional Solutions, VTT Technical Research Centre of Finland, Oulu Finland
The fabrication process and the operation characteristics of a fully roll-to-roll printed Write Once Read Many (WORM) electric memory are presented.The memory operation is based on the Rapid Electrical Sintering (RES) [1,2,3] of metallic nanoparticle structures. The write process is done by applying a voltage across the printed conductor which causes the rapid sintering of the nanoparticles and a consequent, irreversible large decrease in resistivity. Characteristics of the write process are (i) low voltage and power, (ii) short duration (typically 1...10 ms), and (iii) local sintering with low substrate thermal load. The memory thus acts as a two-state device with simple resistive readout. The memory readout can be performed both with contact (resistive) and non-contact (capacitive) methods. The write process can be systematically controlled allowing a multilevel operation to increase the memory capacity. The memory layout contains only two layers: the electrically programmable bit part and the contact electrodes for readout. The roll-to-roll memory fabrication was successfully demonstrated via a test printing run (> 150m printed length, > 10 000 memory cards) at the VTT pilot line. The web path and the printing sequence were as follows: (i) the bit gravure printing using specially formulated silver nanoparticle ink, (ii) oven drying at 140°C for 25 seconds, (iii) the gravure printing of the contact electrodes using a silver microparticle ink by Evonik, and (iv) oven drying at 140°C for 25 seconds. The web speed was 5 m/min and a heat stabilized 125 µm PET-foil (Melinex ST506) was used as the substrate. Roll-to-roll die cutting was used to separate the memory cards from the web. Hot-lamination (manual, non-roll-to-roll) was applied for the test device encapsulation.The electrical performance (write and read characteristics and long-term stability) will be described. The memory content is found to remain stable for at least four months when stored in ambient conditions. The effect of lamination on the long term stability will be discussed.The memory can find use in ultra-low-cost, mass applications such as access passes to online content, product originality markings, electrical questionnaires, and interactive games . The existing product prototypes will be discussed.References: H. Seppä and M. Allen, Patent Application WO 2008/009779 A1. M. Allen, M. Aronniemi, T. Mattila, A. Alastalo, K. Ojanperä, M. Suhonen and H. Seppä, Nanotechnology 19, 175201 (2008). J. Leppäniemi, M. Aronniemi, T. Mattila, A. Alastalo, M. Allen and H. Seppä, ”Printed WORM Memory on Flexible Substrate Based on Rapid Electrical Sintering of Nanoparticles”, IEEE Trans. El. Dev., accepted. A. Alastalo, T. Mattila, J. Leppäniemi, M. Suhonen, T. Kololuoma, et al., ”Printable WORM and FRAM memories and their applications”, Proceedings LOPE-C 2010.
3:15 PM - **D2.3
Roll-to-roll Printed 13.56 MHz Operated 16 Bit RFID Tags and RF Logos on Plastic Foil.
Jinsoo Noh 1 2 , Minhun Jung 1 2 , Joonseok Kim 1 2 , Hwiwon Kang 2 , Soyeon Kim 2 , Kwangyong Lee 1 , Kyunghwan Jung 1 2 , Dongsun Yeom 2 , Yongsu Park 1 , Minjin Lee 1 , Gyoujin Cho 1 2 Show Abstract
1 , Sunchon University, Suncheon Korea (the Republic of), 2 , Paru Co. Ltd., Suncheon Korea (the Republic of)
An ubiquitous low-cost tag society will be fully realized when people can track all items with a radio frequency identification (RFID) system instead of the current barcode system. That means all goods need to have their own RFID tags. To place RFID tags on all goods, the most important factor is the cost of the tags that optimally less than one cent (0.01$). To dramatically reduce the cost of current RFID tags, a roll-to-roll (R2R) inline printing process to print all the units of a passive RFID tag, such as the antenna and transponder, has been considered as an alternative to the current Si-based technology. During the last decade, developing RFID tags using organic semiconductors with a photolithographic process has been demonstrated, however, there has been no report of production of the RFID tags that had been fully printed and R2R printable. The major reasons for the delay in developing all-printed tags originates from the lack of technology for producing an all-printed plastic rectifier that can provide at least 10 volts DC from 13.56 MHz RFID reader, and an all printed-plastic logic circuits that can generate 96 bit of signals to read a 96 bit RFID tag in a second under the DC power provided from the rectifier. Here we describe a way to achieve this goal using plastic foil substrates, and as a consequence of pursuing the ways, R2R printed 13.56 MHz operated 16 bit RFID tags and RF Logos will be demonstrated.
4:30 PM - **D2.5
High Volume R2R Manufacturing of Electronics on Paper and Plastic Substrates.
Goeran Gustafsson 1 Show Abstract
1 , Acreo , Norrkoping Sweden
A lot of effort has been spent on developing organic electronics components. Some of these have shown excellent performance and also printability. However, printed electronics has not yet reached the market. A reason for this is that integration of components into useful products has proven more challenging than expected. One of the major challenges is the large variety of materials and processes that are used in the manufacturing which often results in complex processing lines. Another challenge is how to design electronic systems that can accommodate the differences in drive voltage between different components. We will present a roll to roll printable technology platform of electrolyte based components which consists of displays, TFTs, diodes, sensors and antennas/interconnects. These components have the benefit of being based on a small set of materials and at the same time the components show millisecond switching time at drive voltages around 1 volt. The latter is critical upon integration of TFTs with batteries, displays and sensors. We will also discuss the need for heterogeneous integration of printed electronics with Si electronics and a strategy for making such integration cost effective.
5:00 PM - D2.6
A Digitally Animated Plastic Film Poster from Printed Electronics.
Mark Andrews 1 2 , Bell Fong 2 , William Fong 2 Show Abstract
1 Chemistry, McGill University, Montreal, Quebec, Canada, 2 , Plastic Knowledge, Montreal, Quebec, Canada
It is widely expressed that scalable electronics on plastic (flexible electronics) has the potential to renegotiate the interface between electronics and humans, that the emergence of flexible electronics signals a shift in focus away from increasing miniaturization to products that not only scale with human dimensions, but in effect have the capacity to define new ecosystems in which humans and electronics actively coexist. Ironically, the transformations anticipated by flexible electronics will be achieved by merging not only large-scale electronic platforms with traditional materials and industries, but also by recruiting nanotechnologies, and hybrid combinations of organic and inorganic materials into the service of device fabrication. This presentation describes our advances in fabricating a fully functional electroluminescent digital poster on plastic film using methods that are based solely on print technologies.
5:15 PM - D2.7
Novel Roll-to-roll Manufacturable Strain Sensor for Remote Structural Health Monitoring.
Shivshankar Sivasubramanian 1 , Mario Cazeca 1 , Sharavanan Balasubramaniam 1 , Jung-Rae Park 1 , Joey Mead 1 , Julie Chen 2 , Christopher Niezrecki 2 , Peter Avitabile 2 , Alkim Akyurtlu 3 , Ramaswamy Nagarajan 1 Show Abstract
1 Plastics Engineering, University of Massachusetts, Lowell, Lowell, Massachusetts, United States, 2 Mechanical Engineering, University of Massachusetts, Lowell, Lowell, Massachusetts, United States, 3 Electrical Engineering, University of Massachusetts, Lowell, Lowell, Massachusetts, United States
The development of low cost sensors for remote structural health surveillance has been a challenge in the recent years. The need for a physical connection (between the sensor and the interrogation system) and complex installation/maintenance protocols of conventional strain gauges has necessitated the development of new types of wireless sensors. Here we describe a novel passive wireless strain sensor that can be fabricated by an inexpensive, roll-to-roll (R2R) technique. This sensor is based on a pair of passive inductor-capacitor (LC) elements, which are screen-printed using binder-free silver inks. These sensing elements are electromagnetically coupled and exhibit a distinct resonant frequency when interrogated using radiofrequency (RF) generated by a vector network analyzer connected to a loop antenna. In this wireless strain sensor, the strain can be measured by monitoring the change in the resonant frequency caused by the relative displacement of sensing elements. The binder-free silver inks provide the possibility for fabricating high quality factor sensors with increased sensitivity. Strain measurements made using this wireless strain sensor compare favorably with those obtained using conventional foil-type strain gauges. These strain sensors exhibit a fairly linear change in the resonant frequency with respect to the strain. The formulation of silver inks as well as the fabrication and testing of these sensors will be discussed. This new type of strain sensor that can be potentially fabricated using low cost, R2R techniques is suitable for a variety of applications in the area of wireless structural health surveillance.
5:30 PM - D2.8
Direct-write Printed Flexible Batteries.
Abhinav Gaikwad 1 , Gregory Whiting 1 , Natasha Yamamoto 1 , Brent Krusor 1 , Dan Steingart 2 , Ana Arias 1 Show Abstract
1 , Palo Alto Research Center (PARC), Palo Alto, California, United States, 2 Chemical Engineering, City College of New York, New York, New York, United States
Energy storage is required for many applications of flexible, printed electronics, and the ability to easily customize the power source is potentially useful. This is particularly true for disposable, mobile applications where flexibility is required. For these applications small capacities may be needed, but high driving voltages (~20 V) are often required due to the relatively thick, low k dielectric layers typically used in printed field-effect transistors. Since DC-to-DC up-conversion is presently non-trivial to achieve with printed electronics, in order to source these voltages many cells must be connected together in series. Using currently available products this would often lead to either a large footprint (if connected laterally) or result in a loss of flexibility (if cells are stacked vertically). As such, it is beneficial to tailor the battery properties, providing the necessary size, voltage and capacity for a particular application. Here, we show a method to achieve this using direct-write printing of batteries onto flexible substrates. A pressurized liquid dispensing system is used to drive a viscous solution through a fine needle in order to deposit the battery materials (current collector, electrodes and electrolyte). Using inks made from suspensions of metal(oxide) particles with polymer binders, an example of a printed zinc-manganese dioxide alkaline battery is shown.
5:45 PM - D2.9
Precise Absorbent Ink Deposition and Optical Inspection System.
Andreas Willlert 1 , Enrico Sowade 2 , Christian Rahnfeld 2 , Reinhard Baumann 1 2 , Joerg Lucas 3 , Andreas Heilmann 3 Show Abstract
1 Printed Functionalities, Fraunhofer Research Institution for Electronic Nano Systems ENAS, Chemnitz Germany, 2 Institute for Print and Media Technology, Chemnitz University of Technology, Chemnitz Germany, 3 Interface and Surface Technology, Fraunhofer Institute for Mechanics of Materials IWM, Halle (Saale) Germany
Foils from the ethylene-tetrafluoroethylene (ETFE) copolymer are used as transparent, humidity resistant and UV-stabile facade and roof coverings, e.g. for stadia, indoor swimming pools or greenhouses. With pneumatically supported cushions, large translucent structures can be realised. Up to now, they are assembled through a thermal welding process. Welding techniques using lasers are under way. Laser welding of transparent polymer foils requires an optical absorber placed in the interface between the two welding partners. Usually, dye molecules with absorption properties adapted to the laser wavelength are used as absorbers. At a well-defined temperature, the dye molecules will be chemically modified, and transparent laser welding seams can be achieved. To get reproducible laser welding results, a homogenous layer of absorbent molecules or materials at the welding interface have to be realized, which is often very hard to achieve by wet deposition of dye molecules dispersed in a solution.In our contribution, we report on an inkjet printing system that can be mounted on a R2R manufacturing device. The challenge of this approach is to find the right ink that is compatible with this highly hydrophobic ETFE foil. Therefore, also pretreatment of the substrate as well as the utilization of different inkjet technologies is covered in the contribution. It is demonstrated that the printing of a laser absorbent ink in a defined way onto the substrate is possible.For quality assurance an optical inspection system has been developed to ensure a proper deposition of material. This ensures the quality control for the inkjet printing process of the special functional material. In this part the results of the comparison of the use of a dedicated 14 bit grey level CCD line camera is compared to a high quality web cam. Laser irradiation of the foil with printed laser absorbent lines together with the untreated joining partner was performed by a continuous wave diode laser at a wavelength of 808 nm using a defocused laser spot. A nearly transparent welding seam was achieved. Mechanical tensile tests of the laser welding seams have demonstrated that their tensile strength is comparable to conventional thermal welding seams.This work was supported by the German Federal Ministry for Economics and Technology (Contract 16IN0647).
Jurgen H. Daniel Palo Alto Research Center
Gyoujin Cho Sunchon National University
Thomas Blaudeck Chemnitz University of Technology
Mehmet R. Dokmeci Northeastern University
D3/F6/G7: Joint Session: Novel Manufacturing Strategies for Electronic Devices
Wednesday AM, December 01, 2010
Room 311 (Hynes)
9:30 AM - D3.1/F6.1/G7.1
Chemically Modified Ink-jet Printed Electrodes for Organic Field-effect Transistors.
Gregory Whiting 1 , Tse Nga Ng 1 , Natasha Yamamoto 1 , Ana Arias 1 Show Abstract
1 , Palo Alto Research Center (PARC), Palo Alto, California, United States
Ink-jet printing is a desirable manufacturing technique for electronic devices as this mask-less, additive method should allow for integration of different electronic components over large substrate areas at low cost. In order to realize entirely jet-printed devices, appropriate printed electrodes for organic semiconductor-based field effect transistors (FETs) must be chosen. Generally, gold is used as the source and drain contacts in these devices. While gold creates good contact with many organic semiconductors, its high price makes it non-ideal for large-scale manufacture. There is therefore a desire to investigate other conductors for printed devices, and typically printable conductive inks are silver based, which is lower cost and allows for low-temperature processing, but can lead to poor energy level matching with the organic semiconductor. This report will study the use of both a nanoparticle silver ink as well as a soluble silver precursor ink and will show that by modifying the surface chemistry of the printed silver contacts through solution-based self-assembly of the organic electron acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), the electronic and wetting characteristics of the electrodes can be tailored. Combining these modified electrodes with p-type organic semiconductors such as 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene), and polymer/small molecule (acene-type) blend semiconductors results in a significant improvement in device performance over the untreated electrodes, yielding high-quality devices with field-effect mobilities > 1 cm2 V-1 s-1. The effect of this treatment on field-effect transistors incorporating n-type small molecule organic semiconductors will also be discussed.
9:45 AM - D3.2/F6.2/G7.2
Subfemtoliter Inkjet for 3-V Operation, High Mobility Organic Transistors.
Tomoyuki Yokota 1 , Tsuyoshi Sekitani 1 , Yoshiaki Noguchi 1 , Kenjiro Fukuda 1 , Ute Zschieschang 2 , Hagen Klauk 2 , Tatsuya Yamamoto 3 , Kazuo Takimiya 3 , Masaaki Ikeda 4 , Hirokazu Kuwabara 4 , Takao Someya 1 5 Show Abstract
1 , University of Tokyo, Tokyo Japan, 2 , Max Planck Institute for Solid State Research, Stuttgart Germany, 3 , Hiroshima University, Higashi-Hiroshima Japan, 4 , Nippon Kayaku Co., Ltd., Tokyo Japan, 5 , Institute for Nano Quantum Information Electronics, Tokyo Japan
We have fabricated top-contact p-channel organic transistors with very high transconductance by inkjet technology with subfemtoliter accuracy. A gate dielectric is formed using single-molecule-thick self-assembled monolayer (SAM). Very fine source/drain electrodes with 2-μm-linewidth are printed using subfemtoliter inkjet directly on high mobility organic semiconductors, dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophene (DNTT) , and channel length is systematically changed with ranging from 2.5 μm to 98 μm. The TFT with channel length of 98 μm exhibited a high mobility of 1.2 cm2/Vs within 3-V operation. Furthermore, the TFT with channel length of 2.5 μm exhibited a high transconductance of 254 μS/mm, which is the highest value among organic transistors fabricated by using direct printing methods.These transistors are fabricated by vacuum evaporation, solution, and inkjet printing process. First, 30-nm-thick Al layer is thermally evaporated through a shadow mask as gate electrode. Second, we form a gate dielectric layer, which comprisies thin layers of 4-nm-thick aluminum oxide and 2-nm-thick molecular SAMs (n-octadecylphosphonic acid) . A thin aluminum oxide layer with a large density of hydroxyl groups for molecular adsorption is formed by oxygen-plasma treatment (300W 30 min) and a SAM layers are prepared from a 2-propanolsolution at room temperature. On the dielectrics, 30-nm-thick p-type organic semiconductor DNTT  is patterned by thermal evaporation through a shadow mask. Finally, on the organic semiconductor films, we printed silver lines by inkjet printing systems with subfemtoliter accuracy and sintered at 90 °C for 5 hours in nitrogen environment to form source and drain electrodes.We thank Harima Chemicals for providing high-quality Ag nanoparticles, and SIJ Technology for technical support in the inkjet process. This work is partially supported by Special Coordination Funds for Promoting, JST/CREST and KAKENHI (Wakate S). One of the authors (T.Y.) is grateful to the research fellowships for young scientists of JSPS. This study was partially supported by JST/CREST and NEDO. T. Yamamoto and K. Takimiya, J. Am. Chem. Soc. 129, 2224 (2007). H. Klauk, U. Zschieschang, J. Pflaum and M. Halik, Nature 445, 745 (2007).
10:00 AM - D3.3/F6.3/G7.3
Structure and Properties of Gravure Printed Organic Diodes.
Kaisa Lilja 1 , Timo Joutsenoja 1 , Donald Lupo 1 Show Abstract
1 Department of Electronics, Tampere University of Technology, Tampere Finland
The development of organic electronic components, such as diodes and transistors, offers the possibility to manufacture flexible and lightweight electronics using cost-effective processes. We report characteristics and properties of gravure printed organic diodes that are fabricated using a process that is scalable to high-volume production. The diodes consist of a layer of poly(triarylamine) (PTAA) sandwiched between copper and silver electrodes. A wet etching process where the etch resist was printed by rotary screen printing was used to pattern the copper cathode. The PTAA and silver layers were printed using a laboratory scale automatic gravure printing press. The diode fabrication and characterization was performed in ambient laboratory conditions. The diode characteristics showed no significant degradation after months of storage.Previously, we have demonstrated printed organic diodes as RFID rectifiers and as the active components in a display driving circuitry. [1,2] In these applications, a sufficient rectification ratio is needed. The used diode structure has a significant effect on the performance of the diodes. Here, we report a thin interfacial layer that reduces the reverse current of the printed diodes without having a notable effect on the forward characteristics above 1 V. This enables the diodes to be used for applications that require low reverse currents and/or high rectification ratios.References: K. E. Lilja, T. G. Bäcklund, D. Lupo, T. Hassinen, T. Joutsenoja, Org. Electr. 10 (2009) 1011. K.E. Lilja, T.G. Bäcklund, D. Lupo, J. Virtanen, E. Hämäläinen, T. Joutsenoja, Thin Solid Films. 518 (2010) 4385.
10:15 AM - **D3.4/F6.4/G7.4
Low-temperature, Solution-processing of Organic and Metal Oxide Field-effect Transistors.
Henning Sirringhaus 1 Show Abstract
1 Cavendish Laboratory , University of Cambridge, Cambridge United Kingdom
Organic semiconductors have been considered for some time as an attractive class of materials for realising electronics on plastic substrates by low-temperature solution processing and direct-write printing. However, there are also certain inorganic semiconductors which are amenable to solution processing, in particular metal oxide semiconductors. We have worked on both classes of materials and in this presentation we will present the status of device performance achievable with both approaches and discuss specific aspects of the device and materials physics of organic semiconductor as well as metal oxide field-effect transistors.
10:45 AM - D3/F6/G7:
11:15 AM - **D3.5/F6.5/G7.5
Enabling Roll-to-roll Manufacturing of Flexible Electronics: Advances in Vacuum Deposition, Photolithography and Wet Processing of Thin Film Multilayers on Flexible Polymeric Substrates.
Mark Poliks 1 2 , James Switzer 2 , Paul Wickboldt 2 , Bruce White 2 , Bahgat Sammakia 2 Show Abstract
1 Research and Development, Endicott Interconnect Technologies, Inc., Endicott, New York, United States, 2 Center for Advanced Microelectronics Manufacturing (CAMM), State University of New York at Binghamton, Binghamton, New York, United States
The Center for Advanced Microelectronics Manufacturing (CAMM) is an academic-industry- government research and development center established by an award from the Flex Tech Alliance (formerly called the United States Display Consortium) to Binghamton University, Endicott Interconnect Technologies and Cornell University. The CAMM was established to demonstrate the feasibility of roll-to-roll (R2R) electronics manufacturing by acquiring first generation tools and establishing processes capable of producing low volume prototypes. The CAMM addresses R2R fundamental enabling science, technologies, and system design (integration, performance, yield and manufacturing feasibility) issues. This revolutionary approach will enable both ubiquitous and disposable electronic devices.Recent R2R research activities include: single micron photolithography and interlayer registration on unsupported flexible PET and PEN, as well as vacuum deposition of Al, Si, their oxides and ITO. The CAMM has produced a number of products and technologies including: flexible sensors, intravascular ultrasound devices, flexible polymer optical waveguides and structured surfaces for tailored wetting. Having established this suite of film deposition, lithography and etch capabilities, our next goal is demonstration of thin film transistor fabrication. A process flow based on zinc oxide and gallium indium zinc oxide TFTs is being developed. Sputtered SiO2, PECVD Si3N4 , and sputtered HfO2 are be explored for use as gate dielectrics. The demonstration of these high performance, low cost thin TFTs is a critical first step in generating the process, device, and desgn infrastructure required to realize the revolutionary products enabled by R2R manufacturing.
11:45 AM - D3.6/F6.6/G7.6
Mass-printed Integrated Circuits with Enhanced Performance Using Novel Materials and Concepts.
Heiko Kempa 1 , Mike Hambsch 1 , Kay Reuter 1 , Georg Schmidt 1 , Michael Stanel 1 , Maxi Bellmann 1 , Arved Huebler 1 Show Abstract
1 Institute of Print and Media Technology, TU Chemnitz, Chemnitz Germany
Lab-scale experiments, which were demonstrating the basic suitability for printing of electronic devices and circuits of so-called mass-printing techniques, which are based on patterned ink transfer from rotating cylindrical printing forms to flexible substrates moving with a speed of several m/s and which therefore exhibit an unrivalled productivity for large numbers of copies, resulted in transistor circuits with performances not sufficient for targeted application scenarios.  Further developments aiming at enhanced circuit performance while avoiding decline in productivity have three basic options: i) reduction of critical structure dimensions, ii) enhancement of charge carrier mobility and iii) novel concepts of circuitry.i) Optimization of conventional printing techniques and application of innovative modifications has led to transistor channel lengths below 20 µm, resulting in stage delay times as low as 7 ms.  However, further reduction of these values will be connected with superlinear increase of efforts in terms of investment costs and manpower. In addition, parasitic effects are limiting the reduction of switching times at small transistor dimensions, which require further technological challenges to be overcome.ii) Progress in synthesis and production of soluble organic semiconductor materials has led to impressive progress in this respect. Especially the commercial availability of relevant amounts of printable formulations of small molecules, namely TIPS-Pentacene, with charge carrier mobilities of the order of 1 cm2/Vs has facilitated printing of high-mobility transistors and circuits thereof. iii) Undoubtedly, the introduction of complementary circuitry in printed electronics will lead to an immediate enhancement of circuit performance. Due to the recent availability of stable and printable n-type semiconductors with decent mobility, this process is currently on the way.  However, control of threshold voltage of printed transistors by means of a permanently stored charge in the gate dielectric allows for an alternative quasi-complementary approach using enhancement and depletion transistors that might turn out to be as effective as the usage of different (n- and p-type) semiconductors. We report on progress in terms of performance of mass-printed integrated circuit which goes beyond reduction of critical structure dimensions. In particular, we focus on printing of highly performing p- and n-type semiconductors and on printed quasi-complementary circuits using charged gate dielectrics. A. Hübler et al., Org. Electr. 8 (2007) 480. G. Schmidt et al., subm. to Org. Electr. (2010). S.K. Park et al., IEDM Tech. Digest (2005) 105. H. Yan et al., Adv. Mater. 20 (2008) 3393. K. Reuter et al., Org. Electr. 11 (2010) 95.
12:00 PM - **D3.7/F6.7/G7.7
Towards Roll-to-roll Fabricated Organic Devices.
Paul Blom 1 , Ton van Mol 1 , Ronn Andriessen 1 , Andreas Dietzel 1 , Erwin Meinders 1 , Gerwin Gelinck 1 , Herman Schoo 1 Show Abstract
1 , TNO/Holst Centre, Eindhoven Netherlands
Organic light-emitting diodes (OLEDs) and organic photovoltaic devices (OPV) have the potential to revolutionize the lighting and energy harvesting market. For lighting applications OLEDs made on flexible foils have a number of beneficial properties, such as free form factor, tunable color, being difficult to break compared to glass, having a large area emitting surface, and being potentially very efficient and low cost. For OLED lighting and signage, the layer quality requirements can be harsher as compared to OPV. One of the reasons is that for OLED devices, any (major) layer in-homogeneity causing an electric trouble will result ultimately in a visual defect. For OPV this will “only” affect efficiency. Another difference is that organic light emitting diodes (OLED) are more very sensitive to moisture and oxygen. The cathode, typically BaAl, easily oxidizes and this oxidation leads to formation of black spots. Also the organic emitter can degrade under the influence of oxygen. Both effects are undesired and necessitate the need for good encapsulation of the OLED. Today, OLED’s (on glass) are encapsulated with either a metal or glass lid with a cavity. Despite its effectiveness in terms of encapsulation, glass or metal lid packaging is expensive and prevents the possibility to fabricate thin, flexible devices. At the Holst Centre flexible OLED lighting and OPV architectures are being developed including thin film barriers which can be processed with roll-to-roll (R2R) compatible technology with high yield.
12:30 PM - D3.8/F6.8/G7.8
Self-aligned Fabrication of Flexible Organic Thin Film Transistors by Means of R2R-compatible Nanoimprint Lithography.
Barbara Stadlober 1 , Andreas Petritz 1 , Ursula Palfinger 1 , Thomas Rothlaender 1 , Frank Reil 1 , Herbert Gold 1 Show Abstract
1 Institute of Nanostructured Materials and Photonics, Joanneum Research, Weiz Austria
Organic thin film transistors (OTFTs) need to fulfil several performance requirements in order to be applicable in e.g. active matrix display backplanes. On the one hand high on/off ratios are required in the drain current to achieve a better contrast ratio, on the other hand the area consumption should be as small as possible. Both demands can be met by scaling down the dimensions of the transistors, as smaller channel length values result in higher currents. We’ve realized the miniaturization of flexible OTFTs by use of self-aligned nanoimprint lithography (NIL) for the definition of the source and drain electrodes in the submicron range. PET as well as polycarbonate films were used as the substrate. It is shown that this approach is compatible with different organic dielectric materials, as for example a BCB derivative and an Ormocer™ material. The devices show satisfactory saturation in the output characteristics even for channel length values in the submicron regime as long as proper scaling of the dielectric layer thickness is maintained. The nanoimprinting was either based on hot embossing or on UV-nanoimprint lithography. Self-alignment, which is very important for large-area NIL techniques, was achieved by either utilizing a back-substrate exposure technique or by direct imprinting. In the former approach the nanoimprinted gate layer defines the pattern of the source-drain layer thus resulting in perfect alignment and minimized gate-to-source and gate-to-drain overlaps. In the direct imprint approach a metal layer is applied first on the imprint resist coated flexible substrate followed by the coating of an ultrathin dielectric layer. Then imprinting was performed defining both the gate as well the channel electrodes in one step. The device is finalized by the application of the organic semiconductor. The self-aligned submicron devices are either of n- or p-type and show proper device characteristics with a very large bandwidth as is expected for transistors with minimized electrode overlaps and therefore decreased parasitic gate capacitance.
12:45 PM - D3.9/F6.9/G7.9
Concepts of Metal-organic Decomposition (MOD) Silver Inks for Structured Metallization by Inkjet Printing.
Claudia Schoner 1 , Stephan Jahn 1 , Thomas Blaudeck 1 , Alexander Jakob 2 , Heinrich Lang 2 , Reinhard Baumann 1 Show Abstract
1 Digital Printing and Imaging, Chemnitz University of Technology, Chemnitz Germany, 2 Inorganic Chemistry, Chemnitz University of Technology, Chemnitz Germany
Inkjet printing has gained growing interest in the field of electronics for the manufacture of many devices of printed electronics such as OLEDs or solar cells. Moreover, patterned metallization at ambient conditions is a key issue for a cost-effective manufacturing of passive wiring components. Recently, Jahn et al. introduced the silver(I)-2-[2-(2-methoxyethoxy)-ethoxy]acetat as an aqueous metal-organic decomposition (MOD) ink without additional stabilizing ligands. Based on a silver salt concentration of 23 wt%, conductivities of printed structures of above 10^7 Sm^(-1) were obtained applying thermal or photo-thermal annealing techniques [1, 2]. In this contribution, we report about the further optimization of the MOD ink by varying the solvent base and increasing the silver salt concentration. Five different ink concepts were compared with respect to their key physical parameters relevant for inkjet printing and the final performance, including viscosity, surface tension, and density. The concepts include the usage of N-methyl-2-pyrrolidone as a humectant with low vapor pressure, addition of sodium lauryl sulfate as optional stabilizing ligand or addition of co-solvents such as diethylene glycole or acetonitrile. Following this route, printability could be achieved for inks with silver salt concentrations up to 45 wt% at maintained conductivity. References S. F. Jahn, T. Blaudeck, R. R. Baumann, A. Jakob, P. Ecorchard, T. Rüffer, H. Lang, P. Schmidt, Chemistry of Materials 22 (10), 3067-3071 (2010).  S. F. Jahn, A. Jakob, T. Blaudeck, P. Schmidt, H. Lang, R. R. Baumann, Thin Solid Films 518 (12), 3218-3222 (2010).
Jurgen H. Daniel Palo Alto Research Center
Gyoujin Cho Sunchon National University
Thomas Blaudeck Chemnitz University of Technology
Mehmet R. Dokmeci Northeastern University
D6: Poster Session
Thursday PM, December 02, 2010
Exhibition Hall D (Hynes)
D4: Roll-to-roll Film Deposition and Manufacturing Challenges
Thursday PM, December 02, 2010
Room 308 (Hynes)
9:45 AM - **D4.1
Process Control Challenges in Roll-to-roll Manufacturing of Printable Functional Devices.
Henrik Sandberg 1 , Ari Alastalo 1 , Jukka Hast 1 , Markus Tuomikoski 1 , Mikko Keranen 1 , Terho Kololuoma 1 , Arto Maaninen 1 Show Abstract
1 Printable Functional Solutions, VTT Technical Research Centre of Finland, Espoo Finland
The expectations for printed electronics and other functional printed applications are high with a huge market potential in a variety of sectors. The benefits of printing-type manufacturing include (i) high-speed and low-cost fabrication of high volume products, (ii) flexible substrates and continuous web, allowing for arbitrary size/shape and low-end products, and (iii) possibility to use established technology. Applications may use technology that is economically and environmentally sustainable. VTT develops a wide range of printable functional devices with existing prototypes or products on market for electronic bar codes and code readers (e.g. Nicanti Oy as a joint venture of VTT, Itaca Nova and Vera Venture), diagnostics and testing (e.g. VTT – Orion Diagnostica collaboration) , memory cards (PriMeBits EU project) [A. Alastalo, et al., Proceedings LOPE-C 2010], printed polymer-based solar cells [P. Kopola, et. al., Solar Energy Materials & Solar Cells, 2010] and printed OLED-based lighting elements [P. Kopola, et. al., Thin Solid Films. Vol. 517(19), 2009, p5757]. Processing equipment ranging from table-top printers to roll-to-roll multifunctional processing machines is available. Hardware and process development supplement materials and device science. Roll-to-roll (R2R) processing techniques in addition to printing (gravure, FLEXO, screen and ink-jet) are e.g. inert atmosphere printing, hot embossing, vacuum thermal evaporation, laser processing, lift-off type processing, etching, and lamination. For inks, we rely on functional materials from partners or from commercial vendors, but also have small-scale in-house materials development. For example a low work function cathode ink for optoelectronic devices [T. Maaninen, et. al., IMID07 Technical Digest 7, 2007, p721] has been produced as well as bioactive compounds for indicators. The main challenges related to R2R printing processing are the control and optimization of (i) registration of consecutive fabrication steps (ii) chemical (orthogonal solvents) and physical (band structure, step coverage) compatibility of materials, (iii) wetting properties of the inks, (iv) curing and drying of the inks with limited thermal tolerance of the substrates and sensitive materials layers, (iv) online quality control of the devices to monitor and optimize the process yield, (v) controlled atmospheres needed for sensitive materials and (vi) compatibility of the multi-technological processing steps. In this paper, we discuss the approaches that have proved to overcome many fabrication challenges. These techniques include machine vision for registration monitoring, using different printing techniques along the processing line such as thick-film screen printing to cover high steps, chemical surface modification to control ink behaviour and fast low-temperature non-oven sintering/curing processes. The solutions will be illustrated with case examples of prototype manufacturing using R2R pilot processes.
10:15 AM - **D4.2
Atmospheric Device Processing by Spatial Atomic Layer Deposition.
David Levy 1 , Shelby Nelson 1 , Mitchell Burberry 1 , Lee Tutt 1 Show Abstract
1 , Eastman Kodak, Rochester, New York, United States
Atomic Layer Deposition (ALD) is a chemical vapor deposition process in which films are formed by exposing a substrate to reactants one at a time in order to construct a film atomic layer by atomic layer. The process leads to dense, conformal, pinhole-free films. Typical ALD processes are performed within a process chamber in which the gases are repeatedly introduced then withdrawn from the chamber, yielding the desired film growth. An alternative process is to localize gases spatially to specific regions of a coating head, and to accomplish the growth by relative motion of the substrate to the coating head. While spatial ALD (SALD) systems have been known for some time, we demonstrate a process that has excellent isolation between reactants and the potential for extremely fast gas exposures on the order of 10 ms. Among the advantages of a SALD process are simplicity in the gas handling and the potential for processing large and ultimately continuous roll substrates in an open (chamberless) process.The SALD process is capable of producing high-quality films with growth characteristics typical of standard ALD processes. High-quality insulating films based upon aluminum oxide (Al2O3) show leakage and breakdown characteristic of standard ALD Al2O3 films. In addition, aluminum-doped zinc oxide films (AZO) with bulk resistivity approaching that of the more expensive ITO area are likewise feasible with this system.The high film quality lends itself to high-performance active devices such as thin-film transistors (TFT). Current methods considered for producing TFTs include the industrially mature amorphous silicon (a-Si) process, vacuum processes employing polycrystalline silicon- or zinc-based oxides, and organic semiconductors. The SALD process has the potential to produce mobility and stability that exceeds that of a-Si while in an open process that can lead to manufacturing benefits relative to other manufacturing methods. The performance of TFTs produced from the SALD system will be discussed, as well as useful methods to pattern these devices based upon selective area deposition.
11:15 AM - **D4.3
Hybrid R2R-machine Concept for Aligned Deposition of Functional Materials.
Andreas Willlert 1 , Frank Siegel 2 , Markus Hoesel 2 , Cedric Akowanou 3 , Dominique Knittel 3 , Reinhard Baumann 1 2 Show Abstract
1 Printed Functionalities, Fraunhofer Research Institution Electronic Nano Systems ENAS, Chemnitz Germany, 2 Institute for Print and Media Technology, Chemnitz University of Technology, Chemnitz Germany, 3 UFR Physique et Ingenierie - Campus Meinau, University of Strasbourg, Strasbourg France
Printing technologies are highly sophisticated technologies for image wise material deposition. Due to different demands of printed products concerning e.g. amount of deposited material a variety of technologies have been developed like inkjet, gravure, screen, offset, or flexo printing. The initial intention was a well defined deposition of color to raise visual attraction. The amount of material depends on the substrate that is used, e.g. the volume of ink to color a paper is less than that to color a textile. For this reason the consistency of inks varies e.g. in viscosity (inkjet requires less viscosity than gravure or screen printing).The approach to use printing technologies for functional material deposition instead of color ink utilizes precise mass production technology in new application fields. Depending on the material an appropriate printing technology has to be chosen that matches material consistency and e.g. the viscosity range of the used printing technology. Therefore different functional materials require different printing technologies.In our contribution, we report about a modular laboratory R2R printing press with 140 mm web width that is used as a platform for studying various functional material deposition techniques. For easier use and handling the mounting of all components are done single-sided. Originally equipped with a gravure printing unit only, to the machine an inkjet printhead with optical alignment has been added. Substrates that can be handled range from paper and plastic foil to thin steel tape. Printing pastes that range from low (10 mPa.s) to high viscosities (> 1500 mPa.s) can be printed using this setup.The talk to be given reports about recent research projects using this unique machinery. In the first part of the talk the concept of the machine is presented. The foci are laid onto improvement of the gravure printing unit, the web guide, web conditioning, and the aligned inkjet operation. In the second part a selection of actual research is presented. The focus is laid on projects that deviate from the typical layer deposition thickness of a gravure press that is in the range of 1 µm. Functional layer thicknesses in the order of 0.1 µm to 10 µm can be achieved. Also results of the integrated setup of the inkjet printhead are shown.
11:45 AM - **D4.4
Low-Cost, High-performance, Single-crystal-like, Heteroepitaxial Devices on Flexible, Polycrystalline, Metal/Alloy Substrates via Roll-to-Roll Fabrication for Energy and Electronic Applications.
Amit Goyal 1 Show Abstract
1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
For many energy and electronic applications, single-crystal-like materials offer the best performance. However in almost all cases, the single crystal form of the relevant material is too expensive. Furthermore, the classic problem of the brittle nature of certain materials such as ceramic materials is often an issue. In addition, for many applications, very long or wide materials are required, a regime not accessible by conventional single crystal growth. This necessitates the use of flexible, large-area, long-length, single-crystal-like substrates for epitaxial growth of the relevant device layer for the electronic or energy application in question. Since the factor determining suitability for applications is price/performance, the process used for fabrication of the artificial substrate needs to be very scalable and low-cost. Two substrate technologies that can result in such single-crystal-like substrates have been developed – one is the Rolling-assisted-biaxially-textured-substrates (RABiTS) technology and the other is the Ion-Beam Assisted Deposition (IBAD) substrate technology. Details of substrate fabrication, the texture quality of the substrates, the nature of grain boundaries, and the range of materials that can be epitaxially grown on such substrates will be discussed. The RABiTS technique employs simple and industrially scalable thermomechanical processing routes to obtain long lengths of near single-crystal-like, cube-textured substrates. Epitaxial buffer layers of various cubic oxides (of rock salt, flourite, perovskite and pyrochlore crystal structures) are then deposited in a roll-to-roll configuration using web-coating employing electron-beam evaporation, sputtering, MOCVD and/or chemical solution deposition. As an example of a material for energy and electronic applications, results will be presented for growth of superconductors on such substrates. Kilometer long, single-crystal-like high-temperature superconducting wires are now routinely fabricated using these substrate technologies. Addressing tension and web-handling issues particularly for deposition at high temperatures (600-800) as well as entering and existing vacuum deposition systems in series has been key to the success of the technology. Roll-to-roll depositions have also been used to create self-assembled nanostructures in long-lengths. This technology is presently also being used for low-cost, high-performance semiconductor devices such as photovoltaics, ferroelectrics, multiferroics, and ultra-high density storage.
12:15 PM - D4.5
R2R Processing of Epitaxial Thin films on Flexible, Low-cost Substrates.
Venkat Selvamanickam 1 Show Abstract
1 Mechanical Engineering, University of Houston, Houston, Texas, United States
Epitaxial thin films are needed for high performance materials but are typically produced on expensive, small-sized single crystal substrates. Several applications require such high performance materials on long-length, large-area substrates, but epitaxial films are essentially impossible on conventional substrates used for R2R processing. This problem has been overcome using single-crystalline-like thin film templates on flexible substrates. Using a technique of ion beam assisted deposition (IBAD), single-crystalline-like MgO films have been demonstrated on nickel alloy substrates in lengths of over 1,500 m using R2R processing. Grains of MgO in the IBAD templates are oriented within the substrate plane with a grain-to-grain misorientation of less than 5° over 1,500 m. These templates are then used in R2R epitaxial film growth for various oxides as well as semiconductors by magnetron sputtering over a range of 400 to 850°C. High Temperature Superconductor (HTS) films of YBa2Cu3Ox, 1 to 3 µm in thickness have been grown epitaxially over kilometer lengths by R2R metal organic chemical vapor deposition (MOCVD) using the oxide-buffered substrates. The current carrying capacity of these flexible superconducting films made by R2R processing is comparable to that achieved with films made on rigid single crystal substrates, even when measured over a length of a kilometer ! Power transmission cables have been constructed with such R2R-processed epitaxial superconducting films and have been installed in the U.S. power grid. This concept of R2R processed epitaxial thin films on flexible metal substrates is now being applied towards semiconductor applications including photovoltaics and solid-state lighting. Using appropriate materials for lattice and structural matching, epitaxial germanium films have been demonstrated on R2R processed flexible metal substrates. The films show a very strong Ge (400) orientation and no evidence of (111) or other peaks of Ge indicating the preferential out-of-plane texture. The in-plane texture of Ge shows a clear four-fold symmetry without the presence of other orientations and has been further improved in thicker Ge films to 1° FWHM i.e. grain-to-grain misorientation less than 1° over a large area. Refraction index and extinction coefficient values of the R2R processed epitaxial Ge film grown on metal substrate match well with that from a reference bulk Ge single crystal. Epitaxial (100) GaAs has also been successfully grown by MBE on the Ge films on polycrystalline substrate and strong photoluminescence signal and good optoelectronic properties have been obtained. The ability to grow single-crystalline-like films on flexible, polycrystalline substrates by R2R processing now provides an immense potential to fabricate high quality superconductors and semiconductors on flexible, inexpensive substrates. Progress and challenges in R2R processing of epitaxial thin films on flexible, low cost substrates will be presented.
12:30 PM - **D4.6
Large Area Equipment for Flexible Electronics
Neil Morrison 2 , Hans-Georg Lotz 2 , Kaushal Singh 1 , Robert Visser 1 Show Abstract
2 Alzenau, Applied Materials, Alzenau Germany, 1 Advanced Technology Group, Applied Materials, Santa Clara, California, United States
High quality thin films are an essential element of any successful flexible electronics program. In this paper we will discuss the deposition processes and roll to roll equipment for vacuum depositing thin films at high throughput and for large areas.Examples of potential choices of equipment and processes for transparent conducting oxides, barrier films and solar cells will be given. It will be shown that in situ control of thickness, uniformity as well as keeping particle levels and contamination low in such systems is possible.Examples of large area printing will be shown
D5: Device Fabrication by Imprinting and Transfer Printing
Thursday PM, December 02, 2010
Room 308 (Hynes)
2:30 PM - **D5.1
Large-area Fabrication of Organic Electronic Devices for Multi-component Sensors and Logic Circuits.
Barbara Stadlober 1 , Ursula Palfinger 1 , Herbert Gold 1 , Anja Haase 1 , Alex Fian 1 , Maria Belegratis 1 , Martin Zirkl 1 , Gregor Scheipl 1 , Julien Magnien 1 Show Abstract
1 Institute of Nanostructured Materials and Photonics, Joanneum Research, Weiz Austria
One of the key issues in organic electronics and photonics is the realization and low-cost fabrication of monolithically integrated multi-component devices. Disposable sensors for point-of-care diagnostics and lightweight, flexible sensors for mobile electronic devices are promising application if they can be produced by printing processes. On the other hand, in view of real applications there is a strong need in printed electronic devices to drastically increase performance. One strategy to attack the major challenges in performance which are larger bandwidth of operation, higher circuit speed, lower operation voltage, less power consumption and higher yield is to develop a large-area fabrication route for high-resolution patterning of organic thin film transistors. Since standard printing techniques do not offer feature size <10µm this automatically generates a need for an unconventional high-resolution patterning techniques compatible with large-area production. A patterning technique accounting for this is Nanoimprint Lithography (NIL).Here we report on organic pyro- and piezoelectric sensors that were fabricated by screen and ink-jet printing as well as on the fabrication of high performing organic thin film transistors and circuits with submicron critical feature size. The integrated organic multi-component sensors consist of a capacitive sensing unit, an organic transistor for signal processing and an organic display unit. All components are produced on flexible substrates. The pyroelectric capacitor is based on a ferroelectric fluorinated copolymer, which is highly sensitive to changes in ambient temperature and thus can be used to detect human body movements. The transistor is monolithically integrated on the sensor. For the patterning of the submicron transistors NIL was used in an improved form thus enabling residue-free self-aligned imprinting. The resulting transistors and circuits show excellent electrical properties and high cut-off frequencies.
3:00 PM - D5.2
Roll-to-roll Process Technology for Production of Monodisperse, Shape-specific Particles and Engineered Films.
Andres Garcia 1 , Benjamin Maynor 1 , Derek Schorzman 1 , Michael Hunter 1 , Jacob Sprague 1 Show Abstract
1 , Liquidia Technologies, Research Triangle Park, North Carolina, United States
Here, we describe a roll-to-roll particle manufacturing technology, Particle Replication in Non-wetting Templates (PRINT®), for the production of mono-disperse nanoparticles and microparticles with precise, controllable sizes and shapes. PRINT technology represents a convergence of advanced nanofabrication technologies, roll-to-roll manufacturing, and state-of-the art particle formulation technology. PRINT offers the capability to control particle size, shape and composition to create tailored particle designs for applications in the life sciences and materials sciences. PRINT is based on roll-to-roll micromolding technology which is advantageous for control over particle properties such as size, shape, component loading, particle modulus and surface functionality. Uniquely, this molding approach offers the capability for bulk production of uniform particles with aspherical shapes, which is in contrast to most particle engineering technologies which produce particles with a poly-disperse size distribution and restricted shape control. Liquidia is currently pursuing applications in the life sciences for vaccines and drug delivery where particles are comprised of neat small molecule therapeutics, neat biologics, or drug/excipient mixtures. Particle size, shape, and composition can be optimized for improved performance in areas such as vaccine immunogenicity, therapeutic aerosol delivery, improved drug biodistribution or controlled therapeutic release. Liquidia is also pursuing applications in the materials sciences for patterned films, magnetically or electrically responsive particles and for unique multi-component particles for “smart particle” applications.
3:15 PM - D5.3
Large-area Organic Distributed Feedback Laser Fabricated by Nanoreplica Molding and Horizontal Dipping.
Chun Ge 1 , Meng Lu 2 , Xun Jian 1 , Yafang Tan 1 , Cunningham Brian 1 3 Show Abstract
1 Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 3 , SRU Biosystems, Woburn, Massachusetts, United States
A novel strategy for producing solid state organic distributed feedback (DFB) lasers on flexible plastic substrates has been demonstrated that is compatible with roll-to-roll manufacturing. DFB lasers are used in a wide variety of applications that include communications, sensing, video display, and spectroscopy, while devices based upon organic materials are increasing demonstrating acceptable output power and long-term reliability. The ability to reduce the cost of such components through the use of a roll-based manufacturing paradigm would enable their use in items such as consumer products, disposable labware, and point-of-care clinical diagnostic sensors. Manufacturing methods derived from integrated circuit fabrication, such as electron beam lithography and spin-casting of polymer thin films are not compatible with roll-to-roll processing, although these are the methods most commonly used to produce the submicron grating surface features and <500 nm thin films required for a DFB laser with <10 nm dimensional tolerances. In this presentation, we demonstrate a new method for producing DFB lasers with process-selectable output wavelengths in the visible range (564 nm < λ < 600 nm) on flexible plastic substrates. By combing a nanoreplica-molding process to produce a polymer grating with a period of t=400 nm, and a depth of d = 50 nm, that is subsequently overcoated with a “horizontal dipping” process that produces a dye-doped polymer laser gain medium of thickness t = 400 nm, we demonstrate large area (2x5 cm2) DFB laser continuous surfaces with highly uniform performance. We demonstrate the ability to precisely control the laser output wavelength through modulation of the “horizontal-dipped” polymer film thickness via control of the dipping speed and polymer/solvent ratio. The process may be used to produce continuous laser surfaces or arrays of distinct lasers through design of the silicon wafer molding template that is used during nanoreplica molding, or through post-process patterning. The talk will describe the design of the DFB laser structure, the fabrication process, selection of materials, characterization of device performance, and characterization of process uniformity/reproducibility. We will describe applications of the process to produce a label-free optical biosensor that is incorporated into disposable plastic 384-well microplates for applications in pharmaceutical high throughput screening.
3:30 PM - D5.4
A High Luminance White OLED Fabricated by Contact Imprint.
JwoHuei Jou 1 , TzuYu Ting 1 , ShiangHau Peng 1 , SunZen Chen 2 Show Abstract
1 Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu Taiwan, 2 Center for Nanotechnology, Material Science and Microsystems, National Tsing Hua University, Hsinchu Taiwan
OLEDs have attracted many attentions for their great potential of being next generation lighting and display devices. For extending the applications of OLEDs on modern society, many researches are focused on improving fabricating measures. Thermal evaporation is a traditional method to fabricate OLEDs. Although the highest efficient OLED is produced by this method, it has some disadvantages as regarding mass production, such as expansive instrument investment, and not easy to fulfill large area products etc.. So, it is important to develop a technique to fabricate the large-area OLEDs in a cheaper way. In this work, we use contact imprinting method to imprint the emissive layer of the white OLED to harvest a maximum luminance over 11000 nits. Considering the imprinting process can be further modified as roll-to-roll process, the success of primary work indicates its great potential on fabricating large area OLEDs in a low cost measure in the future.
3:45 PM - D5.5
Direct Measurement of Compressive Residual Strain in Stiff Brittle Films on Compliant Substrates.
Willem-Pier Vellinga 2 1 , Jeff De Hosson 2 1 Show Abstract
2 , Materials Innovation Institute, M2i, Delft Netherlands, 1 , Applied Physics, University of Groningen, Groningen Netherlands
Coatings of stiff brittle films on compliant substrates are relevant as barrier layers in flexible electronics against ingression of water vapor and oxygen. Defects and cracks in such barrier layers limit their effectiveness, and crack growth during the lifetime of the barriers is therefore a growing field of investigation.So-called fragmentation tests are often used to study critical breaking strains and defect properties of such films. The critical breaking strain and crack driving forces depend sensitively on the internal stress state of the deposited film and curvature methods are often used to asses such residual stresses. These methods rely on the knowledge of thin film and substrate mechanical properties. A method is proposed and illustrated here to measure compressive residual strains in such films directly, i.e. without prior knowledge of thin film and substrate moduli. Since it is basically a fragmentation test the critical strain is measured simultaneously. The method depends on the measurement of hysteresis in the film resistance as a function of strain during a single mechanical loading (e.g. uniaxial tension) cycle during which the critical strain in the film is reached. In case of non-conducting layers it relies on the resistance of an extremely thin conducting "probe" film deposited on top of the film of interest. Examples of the method will be shown for model systems of silicon nitride and silicon oxide films on PEN. The potential usefullness of the method in a more precise determination of the critical strain and as a way of determining the thin film modulus will be discussed.
4:30 PM - **D5.6
Contact Printing of Nanowire Parallel Arrays for Large-Scale Integration of Flexible Electronics and Sensors.
Ali Javey 1 Show Abstract
1 EECS, UC Berkeley, Berkeley, California, United States
Large-scale assembly of highly ordered nanowire (NW) array on flexible substrates through a simple contact printing process is presented. In this device platform, since NW arrays are utilized, the stochastic device-to-device variation is drastically reduced which is of practical importance. The potency and versatility of the method is demonstrated by large-scale, heterogeneous integration of NWs for image sensor circuitry by utilizing optically active NW sensors and high mobility NW transistors. The NW-array sensor and electronic devices are interfaced to enable an all-NW circuitry with on-chip integration, capable of detecting and amplifying an optical signal with high sensitivity and precision. Furthermore, for the first time, truly macro-scale (~7x7 cm2) integration of NW electronics is demonstrated as the active matrix backplane of a flexible pressure sensor array (18×19 pixels). The integrated sensor array effectively functions as an artificial electronic skin, capable of monitoring applied pressure profiles with high spatial resolution. Finally, the performance limits of NW-array transistors are explored by direct RF measurements. The mechanically flexible devices with a channel length of ~1.5 µm exhibit an impressive maximum frequency of oscillation, fmax ~ 1.8 GHz and a cutoff frequency, ft ~ 1 GHz. The results demonstrate the potential of NW-array devices for ultra high frequency (UHF) electronic circuits.
5:00 PM - D5.7
A Quality Map of Nano Transfer Printing.
Teng Li 1 2 , Matthew Tucker 1 Show Abstract
1 Department of Mechanical Engineering, University of Maryland, College Park, Maryland, United States, 2 Maryland NanoCenter, University of Maryland, College Park, Maryland, United States
Nano transfer printing is a nanofabrication technique that involves an assembly process by which a printable layer can be transferred from a transfer substrate to a device substrate. It holds promising potential to enable the roll-to-roll printing process of flexible electronics. The future success of nano transfer printing toward R2R printing hinges upon the understanding on the multi-physics mechanisms governing transfer printing quality, which is far from mature. So far, the quality control of nano transfer printing has been mainly explored via massive experimental trials, which are both time-consuming and cost-prohibitive. In this paper, we conduct systematic computational modeling to investigate the governing mechanisms of the nano transfer printing process. While the existing understanding of nano transfer printing mainly relies on the differential interfacial adhesion, our results suggest that both interfacial defects (e.g., cracks) and differential interfacial adhesion play pivotal roles in the nano transfer printing quality. The outcomes of this study define a multi-physics quality map of nano transfer printing in the space spanned by the critical mechanical properties and geometrical parameters in a transfer printing structure. Such a quality map offers new insights and quantitative guidance for material selection and design strategies to achieve successful nano transfer printing, which can potentially pave the road toward R2R printing of flexible devices.
5:15 PM - D5.8
Transfer of Template Patterned Carbon Nanotubes to a Polymer Surface Using the Thermoforming Process.
Arun Kumar 1 , Ming Wei 1 , Carol Barry 1 , Ahmed Busnaina 2 , Joey Mead 1 Show Abstract
1 Centre for High Rate Nanomanufacturing , University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 Centre for High Rate Nanomanufacturing , Northeastern University, Boston, Massachusetts, United States
Carbon nanotubes (CNT’s) are of interest because of their high thermal, mechanical, and electrical properties. They are often combined with polymers to enhance the properties; however, it would be useful for a number of applications to incorporate the CNT’s in a patterned structure. In this work we investigate an approach to pattern the carbon nanotubes and transfer this pattern to a polymer substrate using thermoforming, a commercially relevant process. Single-wall carbon nanotubes (SWCNT) are deposited electrophoretically onto an interdigitated templates followed by transfer to a polyurethane film by thermoforming. The interdigitated template had a gold (Au) wire with a width of 2-7 µm. Polyurethane sheets are examined using the scanning electron microscope (SEM) for the continuity of the SWCNT transfer. The thermoforming process parameters (temperature (heating time), forming time and vacuum) were optimized to obtain transfer of the patterned SWCNT’s to the polyurethane surface.
5:30 PM - D5.9
Modeling of Adhesion and Contract During Cold Welding, Lamination and Roll-to-roll Fabrication.
Jing Du 1 2 , Wali Akande 1 3 , Tiffany Tong 1 3 , Wole Soboyejo 1 2 Show Abstract
1 The Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, New Jersey, United States, 2 Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, United States, 3 Department of Electrical Engineering, Princeton University, Princeton, New Jersey, United States
This paper presents the results of an experimental and analytical/computational study of the role of adhesion and surface roughness/impurities in the contact between surfaces that are relevant to the fabrication of organic light emitting devices (OLEDs) and organic solar cells. The effects of surface roughness and adhesion are modeled using experimental measurements that are obtained using atomic force microscopy and fracture mechanic techniques. These are incorporated in analytical and finite element models of contact due to lamination and cold welding processes that are relevant to roll-to-roll fabrication. The implications of the results are discussed for the fabrication of robust organic electronic structures.
5:45 PM - D5.10
Transfer and Integration of Organic Nanofibers.
Kasper Thilsing-Hansen 1 , Jakob Kjelstrup-Hansen 1 , Horst-Guenter Rubahn 1 Show Abstract
1 MCI, University of Sourthern Denmark, Soenderborg Denmark
In the past decade, there has been a tremendous progress in the implementation of inorganic one-dimensional nanostructures as active components in electronic devices such as transistors, sensors and flexible displays. These nanostructures are typically grown via different bottom-up techniques, resulting in crystalline material with several beneficial properties such as high charge carrier mobility and well-defined hetero-junctions. One of the challenging aspects is that of transferring the nanostructures to a device substrate and interfacing them to the necessary circuitry. In recent years, several transfer techniques have been demonstrated for transfer of inorganic nanostructures such as Ge, Si and InAs nanowires. These techniques include stamping , printing  and molding . Despite several unique advantages compared to their inorganic counterparts, fewer studies have apparently been made on transferring organic one-dimensional nanostructures from their growth substrates. Organic molecules such as para-hexaphenylene grow under high vacuum conditions via molecular beam epitaxy on freshly cleaved and heated muscovite mica substrates into elongated, mutually parallel nanofibers. These nanofibers exhibit interesting optical properties such as polarized luminescence, wave guiding, and lasing. They are single crystalline with the individual para-hexaphenylene molecules only interacting via weak Van der Waals bonds, resulting in a fragile nature which complicates any transfer process.Here, we report a stamping technique that transfers the organic nanofibers directly from their growth substrate muscovite mica and onto a prefabricated receiver substrate, without any use of sticking layer on the receiver substrate. It has previously been shown that the organic nanofibers can be released from their growth substrate by placing a water droplet on the nanofiber mica sample . By the use of this knowledge, organic nanofibers are transferred in an atmosphere with a controlled humidity, leading to small water droplets condensing on the receiver substrate. This is followed by pressing the receiver substrate against the nanofiber mica sample, thereby transferring the organic nanofibers. The great advantage of this technique is that the mutual parallel orientation of the nanofibers is preserved after the transfer. We also present initial results from studies of the electrical properties of transferred nanofibers.
D6: Poster Session
Friday AM, December 03, 2010
Exhibition Hall D (Hynes)
9:00 PM - D6.1
Ink Transfer Mechanism of Gravure Off-set Printing.
Inyoung Kim 1 , Taik-min Lee 1 , Jae-Ho Noh 1 , Kwang-Seop Kim 1 , Jeongdai Jo 1 , Dong-Soo Kim 1 , Jae-Hyun Kim 1 , Hak-Joo Lee 1 Show Abstract
1 Research division of nano-mechanical system, Korea Institute of Machinery & Materials (KIMM), Daejeon Korea (the Republic of)
Traditional printing technology has been breaking new ground in the electronics as a manufacturing process replacing the photolithography based on vacuum process. Among various printing methods, roll-to-roll based printing has shown the merit as the mass-production process. Therefore, the next-generation devices such as solar cell, flexible displays, touch panel, thin film transistor, or smart labels have been applied to the roll-to-roll based printing processes such as gravure or gravure off-set printing. In this so called printed electronics, printing resolution and aspect ratio has become incomparably important more than the graphic printing. Gravure off-set printing has shown the merits of higher printing resolution and the smaller printing impact on the substrate than gravure printing. However, the printing process became complicated more than gravure because another plastic unit is inserted into printing unit of gravure. Recently, the understanding of printing mechanism has been urgently needed as the printing resolution becomes smaller capable to be applied to the electronic devices. In this study, ink transfer mechanism of gravure-offset printing was analyzed through the measurement of ink-ink cohesion and blanket-ink adhesion using a tribometer. Our gravure-offset printing unit was composed of engraved plate, blanket roll, impression plate, doctor blade, and ink fountain, which was developed for the electrode of flat panel display . During the printing, ink was doctor-bladed onto the engraved plate, usually called cliché and then transferred to polydimethylsiloxane (PDMS) blanket on an off stage. On this stage, all the ink could not be transferred from the cliché to the blanket. However, the ink on the blanket was transferred to substrate completely on a set stage. Therefore, the ink-ink cohesion can be measured on the off stage and the blanket-ink adhesion can be measured on the set stage. Effect of various printing conditions, such as printing pressure, printing velocity, delay time, was investigated on the printing quality. In the case of ink-ink cohesion, the printing pressure did not induce a serious change but the blanket-ink adhesion was affected by the pressure changes, tremendously. Moreover, the opposite trend was observed in the changes of blanket-ink adhesion between the off stage and the set stage. The main factor should be the solvent absorption of ink on the interface between blanket and ink and these phenomena was discussed with the analysis of surface energy changes of blanket, PDMS and ink viscosity. T. -M. Lee, J. –H. Noh, C. H. Kim, J. Jo, D. –S. Kim, Thin solid films, 518 (2010) 3355-3359.
9:00 PM - D6.2
Solution Deposition Planarization of Long-length Flexible Substrates for High Temperature Superconducting Coated Conductors.
Chris Sheehan 1 , Yehun Jung 1 , Terry Holesinger 1 , Cynthia Edney 2 , Jon Ihlefeld 2 , Paul Clem 2 , Vladimir Matias 1 Show Abstract
1 Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Roll-to-roll fabrication of electronic and power devices with single-crystal properties are desired for inexpensive production. We demonstrate an inexpensive method for preparing extremely smooth substrates in large areas. This method utilizes multiple chemical solution depositions to planarize the substrate to a desired level of smoothness. We demonstrated 0.5 nm RMS roughness on a µm scale of oxide coatings on metal tapes that start at 50 times higher roughness. Surface roughness reduction is modeled via film shrinkage during solution deposition and a residual roughness derived from the amorphous film thickness. By utilizing solution deposition of a-Y2O3 to planarize the substrate we create the required surface for in-plane MgO texturing using assisted ion-beam deposition. We have achieved in-plane texture FWHM of 4° on the SDP substrates. Using an appropriate simple layer architecture for superconducting coated conductors we attained critical currents in excess of 3 MA/cm2 at 75 K for 1-1.2 µm thick YBa2Cu3Oy films.
9:00 PM - D6.3
Fe-42%Ni Austenitic Alloy as a Novel Substrate for Flexible Electronics.
Xiaoxiao Ma 1 , Shahrukh Khan 1 , Miltiadis Hatalis 1 , Mark Robinson 2 Show Abstract
1 Electrical and Computer Engineering, Lehigh Universiry, Bethlehem, Pennsylvania, United States, 2 , Ametek Specialty Metal Products Division, Lancaster, Pennsylvania, United States
Metal substrate has been playing a critical role in flexible electronics fabrication especially in R2R process due to its high yield strength after cold rolling and annealing; much higher melting point than polymers which enables high processing temperature with thermal and dimensional stability under thermal cycling; high resistivity to chemical attack; low permeability to water and oxygen; cold workability and compatibility to established low temperature TFT fabrication process. In this study, dimensional stability during thermal cycles and bending tests are applied to nine commercially available metal foils (SS301, SS302, SS304, Ni, Fe-36%Ni, Fe-42%Ni, Ti, Ta and Mo) to determine their potential as substrates for the manufacture of flexible displays. All of those metals foils are cold rolled to finish gauge, 100 microns by highly polished work rolls with surface roughness varying from 25nm to 51nm. They are exposed to various chemicals used in TFT processing and examined by both quantitative and qualitative analysis to determine the proper cleanser to be used and whether extra protection layer is needed for the metal substrates. Dimensional stability test and mechanical flexing are also measured for 9 selected metals.Among all those candidates, Fe-42%Ni austenitic alloy presented the most superior dimensional stability during thermal cycles due to its high melting point (1440°C) and also low and nominally constant coefficient of thermal expansion (6ppm) over a wide temperature range from room temperature to 300°C and good performance in mechanical flexing due to its high yield strength after cold rolling (724MPa) and annealing (276MPa). Thus, it is recommended as substrate for flexible electronics applications. Large isotropic grains with diameters varying from 10um to 50um are observed after pre-annealing at 800°C for 1hr in N2 ambient. This pre-annealing process with dislocation redistribution and recrystallization stabilizes the metal for thermal cycling that minimizes thermal run-out during device fabrication. Fe-42%Ni alloy substrate with pre-annealing exhibits less than 5ppm thermal run-out for 400°C processing and less than 40ppm thermal run-out for 800°C processing whilst substrates without stabilization shows a thermal run-out more than 120ppm for 400°C processing and more than 500ppm for 800°C processing. For bending test, Fe-42%Ni alloy strips are wrapped around cylinders with different radius for multiple times and degree of spring back of the metal substrate after reloading is also measured. Fe-42%Ni can be bent to radius less than 1.9cm without any plastic deformation which is superior to SS304 (3.15cm) tested under same condition. Due to this flexibility and rollability, Fe-42%Ni will be a good choice for R2R process. Low temperature IGZO TFTs are built on this substrate to test its compatibility with device fabrication process. Well behaved TFTs with channel length of 16um present mobility of 14.1 cm2/V.s and threshold voltage of 3.2V.
9:00 PM - D6.5
Rollable Transparent Glass-fabric Reinforced Hybrimer Substrate (GFRHybrimer) for Fabication of Flexible Devices.
JungHo Jin 1 , Ji-Hoon Ko 1 , SeungCheol Yang 1 , Byeong-Soo Bae 1 Show Abstract
1 Lab. Optical Materials & Coating(LOMC), Dept. of Materials Science & Engineering, KAIST, Daejeon Korea (the Republic of)
A rollable transparent glass-fabric reinforced composite film (GFRHybrimer) which can be used as a flexible substrate is introduced. The GFRHybrimer film was fabricated via impregnation of a woven glass-fabric (E-glass) with sol-gel derived organic/inorganic hybrid materials (hybrimer) as the matrix. High optical transparency of the GFRHybrimer could be secured via precise matching of refractive index of the glass-fabric and hybrimer matrix. Additionally, the use of glass-fabric enabled not only a significant reduction in the film’s CTE, but also a remarkable improvement in modulus and flexibility. The GFRHybrimer film exhibited a low coefficient of thermal expansion (CTE) of 13 ppm/°C, a high modulus (~10 GPa) with almost Tg-less characteristic, high optical transparency (~89%), high thermal stability (~370°C), and excellent flexibility (rollable). The performance of the GFRHybrimer as a flexible substrate was verified by successful fabrication of an IGZO (indium gallium zinc oxide) TFT and an a-Si:H based solar cell. Especially, a novel fabrication method for flexible devices, so called GReCoSS process (Glass-fabric Reinforced Coating Films on Surface-treated Substates) was used in the TFT and solar cell fabrication. With this method, flexible oxide TFT and solar cell backplanes could be released from a glass carrier plate without using any adhesives or additional technique such as laser release.
9:00 PM - D6.6
Preparation of Polymers Conjugated with π-extended Quinone Optical and Redox Properties of the Polymers.
Eiji Yoshikawa 1 2 , Timothy Swager 1 2 Show Abstract
1 Chemistry, Massachusetts institute of technology, Cambridge, Massachusetts, United States, 2 , Institute for soldier nanotechnologies, Cambridge, Massachusetts, United States
Conjugated polymer semiconductors offer an advantage over other materials in such device applications as photovoltaic cells, light emitting diodes, and field-effect transistors, since the polymers can be fabricated in large area by low-cost solution processing techniques. Although excellent p-type polymers are readily available, stable n-type polymers remain largely elusive. Development of conjugated high electron affinity polymers remains a critical challenge in these fields. We have synthesized π-conjugated polymers with extended quinone electrophore in the backbone. Optical and redox properties of the polymers will be described.
9:00 PM - D6.7
Synthesis, Growth, and Phase Transitions in Iron Sulfide Nanoparticles.
Jaewon Jang 1 , Steven Volkman 1 , Vivek Subramanian 1 Show Abstract
1 EECS, UC Berkeley, Berkeley, California, United States
FeS2 is a promising material for a range of electronic applications due to its relatively small bandgap and high optical absorption. As a result, it has been considered for use in photovoltaic and absorber applications in various electronic systems. FeS2 nanoparticles are particularly attractive since the offer a solution-based route to achieve FeS2 thin films, making them candidates for use in printed electronics and printed photovoltaics. Here, we study the synthesis, growth, and phase transitions in iron sulfide nanoparticle systems. In particular, we study the various transitions involved in the realization of pyrite FeS2, which is the most attractive phase of iron sulfide for numerous electronic applications. FeS nanoparticles were synthesized at room temperature in water using FeCl3.6H2O and NaSH. FeS particles form in a metastable, strained state and continue to grow from 5 nm to over 100 nm in size, depending upon growth time. We show, using X-ray diffraction (XRD) experiments and transmission electron microscopy measurements (TEM), that when the crystallite size exceeds about 100 nm, the particles amorphize. By controlling the acidity of the solution, we can control the phase of FeS2 which subsequently forms from the amorphous material (either marcasite or pyrite). Over 24 hours, at a pH of 3.3, marcasite forms; at a pH of 3.8, a mixture of marcasite and pyrite form; and at a pH of 4.5, pyrite forms exclusively. The pyrite crystallite size that results is 30-70 nm based on both XRD and TEM.
9:00 PM - D6.9
Deposition of Bi-dispersed Particles in Inkjet-printed Evaporating Colloidal Drops.
Viral Chhasatia 1 , Abhijit Joshi 1 , Ying Sun 1 Show Abstract
1 Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania, United States
Environmentally-benign R2R fabrication using inkjet printing on flexible substrates is an enabling technology that will provide desired high-volume, low-cost production of flexible electronics. However, the intrinsic limits on the spatial accuracy of ink-jetting devices, wetting, de-wetting, contact line pinning, interfacial instabilities, microflows within the deposited drop, and the self-assembly of particulate matter during drop evaporation all contribute to the lack of precise control of deposited electronic materials. In this study, the deposition behaviors of inkjet-printed evaporating colloidal drops consisting of bi-dispersed micro and nano-sized particles are investigated by fluorescence microscopy and SEM. The results on hydrophilic glass substrates show that, the evaporatively-driven outward flow inside the drop drives nanoparticles to deposit close to the pinned contact line while an inner ring deposition is formed by microparticles. This size-induced particle separation is consistent with the existence of a wedge-shaped drop edge near the contact line region of an evaporating drop on a hydrophilic substrate. The replenishing evaporatively-driven flow assembles nanoparticles closer to the pinned contact line forming an outer ring of nanoparticles and this particle jamming further enhances the contact line pinning. Restricted by the wedge-shaped drop edge, microparticles fail to move near the pinned contact line, thereby forming an inner ring inside the nano-sized deposits.This size-induced particle separation presents a new challenge to the uniformity of functional materials in bioprinting applications where nanoparticles and micro-sized cells are printed simultaneously. On the other hand, particle self-assembly based on its size enables easy and well-controlled pattern formation. Here, the effects of particle size contrast, substrate surface energy, and relative humidity of the printing environment on particle separation are examined in detail. The results show that the relative humidity plays an important role in particle deposition morphology. In addition, particle deposition on low surface energy substrates such as PET and PEN reveals different separation mechanism compared to their high energy counterparts due to continuous contact line depinning during drop evaporation.