Viktoriia E. Babicheva, Georgia State University
Sasan Fathpour, University of Central Florida
Juejun Hu, Massachusetts Institute of Technology
Volker J. Sorger, The George Washington University, School of Engineering and Applied Science
GG3: Light Emitting Devices I
Volker J. Sorger
Viktoriia E. Babicheva
Monday PM, November 30, 2015
Hynes, Level 1, Room 103
2:30 AM - *GG3.01
Microscale Light Emitting Diodes and Lasers for Multifunctional Display Systems and On-Chip Optoelectronics
John A. Rogers 1
1Univ of Illinois Urbana United StatesShow Abstract
This talk summarizes advances in the development of microscale, high-performance light emitting diodes and lasers together with methods for their rapid, deterministic assembly on foreign substrates, ranging from silicon wafers to glass plates and plastic sheets. Applications in hybrid integration of III-V devices on Si platforms for next generation photonic integrated circuits will be highlighted.
3:00 AM - GG3.02
Nanoporous Metal Thin Films: Multifunctional Platforms for Influencing the Performance of Organic Light-Emitting Devices
Zeqing Shen 1 Deirdre O'Carroll 2 1 3
1Rutgers University Piscataway United States2Rutgers University Piscataway United States3Rutgers University Piscataway United StatesShow Abstract
To expand their applications in commercial products, methods to increase organic optoelectronic device efficiency are attracting a lot of attention. Many studies focusing on tuning the molecular morphology, photophysics and electrical properties of organic materials to improve internal quantum efficiency of the devices or improving the light extraction/trapping ability of the device structure have been conducted to improve device efficiencies . In our study, we investigate nanoporous metallic thin films as multifunctional platforms for influencing molecular organization, photophysics and light-management in organic conjugated polymer semiconductor thin films for optoelectronic applications.
Nanoporous Ag (NPAg) thin films (>1.5 cm2) with different pore sizes and porosities are fabricated using the thermally-assisted dewetting method . Grazing-incidence wide-angle X-ray scattering data show that conjugated polymer chain organization can be affected by NPAg in different ways. For example, NPAg can increase the fraction of edge-on oriented poly(3-hexylthiophene) (P3HT) chains and decrease the intermolecular π-π stacking distance relative to P3HT on planar Ag. For smaller pore widths and larger porosity, the changes are more pronounced. However, for polyfluorene-based polymers (poly(9,9-dioctylfluorene), PFO and poly(9,9-dioctylfluorene-alt-benzothiadiazole, F8BT) only NPAg with larger pore size is found to alter chain orientation. These observed changes in molecular organization with pore size and porosity could allow the electrical properties of organic active layers in thin-film optoelectronic devices to be tuned .
Moreover, significant photoluminescence (PL) enhancements were achieved for PFO (up to 22), F8BT (up to 18) and P3HT (up to 26) on NPAg films relative to that on glass. Four mechanisms are propose to contribute to the large PL enhancement: 1) redistribution of emission by Ag; 2) redirection of emission by nanopores; 3) local electromagnetic field effects; and 4) polymer chain morphology changes caused by NPAg. Both redistribution and redirection of emission by Ag and the nanopores are believed to be the most important emission enhancement factors in polymers with high intrinsic quantum efficiencies (IQE) (i.e., PFO and F8BT). While redistribution of emission by Ag and local electromagnetic field effects were believed to be the most important factors in polymers with low IQE (i.e., P3HT) . Angle-resolved PL measurements are under way to study the redirection ability of nanopores together with single-pore spectroscopy and time-resolved absorption and emission measurements to investigate local electromagnetic field effects of NPAg.
 C. E. Petoukhoff, Z. Shen, M. Jain, A. Chang, D. M. O&’Carroll, J. Photon. Energy. 2015, 5, 057002
 Z. Shen, D. M. O&’Carroll, Adv. Funct. Mater. 2015, 25, 3302
 M. Aryal, K. Trivedi, W. Hu. ACS Nano. 2009, 3, 3085
3:15 AM - GG3.03
Dynamic Control of Erbium Spontaneous Emission at Sub-Lifetime Speeds Using VO2 Phase-Change
Sebastien Cueff 1 3 Dongfang Li 1 You Zhou 2 Franklin Wong 2 Jonathan A Kurvits 1 Shriram Ramanathan 2 Rashid Zia 1
1Brown University Providence United States2Harvard University Cambridge United States3Institut des Nanotechnologies de Lyon Lyon FranceShow Abstract
The high quantum yield of phosporescent emitters makes them widely used in devices such as amplifiers, displays, lasers, and LEDs. However, these quantum emitters are usually considered impractical for high speed applications because of their intrinsically long lifetimes.
We will present a new framework to transform “slow” phosphorescent emitters into high-speed integrated nanoscale light sources, without affecting their high quantum efficiency. Rather than modulating the excited state electronic population of the emitter, we dynamically control the local optical environment and directly modulate the emission rate into different modes. For that purpose, we leverage the ultrafast insulator-to-metal transition (IMT) of vanadium dioxide as well as the multipolar nature of erbium ions to demonstrate a nanoscale device with direct all-optical modulation of spontaneous emission 3 orders of magnitude faster than the lifetime limit (and with the potential for many more orders of magnitude improvement).
This principle provides a simple way to circumvent the intrinsic lifetime limit of Erbium ions and modulate their emission at high speeds. Such devices would have direct applications at the interface of communication, display, and lighting technologies as well as in biological and chemical sensing.
3:30 AM - GG3.04
Flexible and Multi-Colored Organic/Inorganic Hybrid Perovskite Light-Emitting Diodes
Tae-Woo Lee 1 Young-Hoon Kim 1 Himchan Cho 1 Jin Hyuck Heo 2 Tae-Sik Kim 1 NoSoung Myoung 3 Chang-Lyoul Lee 3 Jin-Woo Byun 1 Sang Hyuk Im 2
1POSTECH Gyungbuk Korea (the Republic of)2Kyung Hee University Suwon Korea (the Republic of)3Gwangju Institute of Science amp; Technology Gwangju Korea (the Republic of)Show Abstract
Organic/inorganic hybrid perovskites (OIPs) have been intensively studied as a promising next-generation emitters alternating conventional organic and inorganic quantum dot (QD) emitters due to high color-purity light (full width at half maximum (FWHM) ~ 20 nm) arising from exciton confinement between organic and inorganic 2-dimensional alternating layers, and their comparable ionization potential (IP) and electron affinity levels with those of typical organic materials. Despite the OIP&’s high color-purity and comparable electronic energy levels with organic semiconductors, bright electroluminescence (EL) of OIPs has been limited due to their severe intrinsic problems such as significant thermal ionization and delocalization at room temperature.
To achieve the bright EL and high efficiency in organic/inorganic hybrid perovskite light-emitting diodes (PrLEDs), large hole injection barrier from low work-function (WF) of PEDOT:PSS (~5.2 eV) to deep ionization potential (IP) of OIPs (~5.9 eV) and severe exciton quenching at the interface between PEDOT:PSS and OIP layer should be overcome. To solve those problems, we used multifunctional self-organized buffer hole injection layer (Buf-HIL) composed of PEDOT:PSS and perfluorinated polymeric acid (PFI). The WF of the self-organized gradient Buf-HIL increased gradually from the bottom surface (ca. 5.2 eV) to the top surface (ca. 5.95 eV) due to self-organization of the PFI. This gradually increasing WF can facilitate hole injection into the OIPs by reducing the hole-injection energy barrier more efficiently than can PEDOT:PSS. Furthermore, the self-organized PFI which is enriched on the top surface of the Buf-HIL can prevent exciton quenching that occurs at the interface between HIL and EML. Finally, we successfully demonstrated organic/inorganic hybrid PrLEDs with a sharp green emission (FWHM ~ 20 nm), high luminance (417 cd/m2), current efficiency (0.577 cd/A) and external quantum efficiency (0.125 %) by using CH3NH3PbBr3 as an emitting layer and Buf-HIL. Furthermore, we fabricated flexible PrLEDs on the plastic substrate for the first time. We also demonstrated multicolored PrLEDs (400 nm < lambda; < 780 nm) by substituting halogen ions (CH3NH3PbClxBryI3-x-y) and organic ammonium cation (CnH2n+1NH3PbBr3).
GG4: Quantum Dots
Volker J. Sorger
Viktoriia E. Babicheva
Monday PM, November 30, 2015
Hynes, Level 1, Room 103
4:15 AM - GG4.01
Polariton Emission from Colloidal Quantum Dots Strongly Coupled to Plasmonic Films
Sriharsha Venkata Jayanti 1 2 Kevin McPeak 1 David K. Kim 1 Paul R. Erickson 3 Sven Burger 4 5 Jian Cui 1 Ferry Prins 1 Stephan Kress 1 Aurelio Rossinelli 1 Kristopher McNeill 3 David J. Norris 1
1ETH Zurich Zurich Switzerland2University of Minnesota Minneapolis United States3ETH Zurich Zurich Switzerland4Zuse Institute Berlin Berlin Germany5JCMwave GmbH Berlin GermanyShow Abstract
Colloidal quantum dots are color-tunable, robust and bright dipole emitters that can couple to surface plasmons, electromagnetic waves bound to a metal&’s surface. When strongly coupled, light and matter states hybridize to form polariton states, which can lead to important technological advances in quantum information processing and thresholdless lasers. Despite their promise, most studies have only observed weak coupling between colloidal quantum dots and surface plasmons. Here, we demonstrate strong coupling between CdSe/CdS/ZnS core-shell quantum dots and high quality plasmonic structures, manifesting as an avoided crossing in the surface plasmon dispersion plot. With the guidance of electromagnetic simulations, large-scale silver hole arrays and quantum dots are precisely tuned to overlap both energetically and spatially to maximize light-matter interactions. When optically excited, we observe polariton emission from these states at room temperature, and obtain a Rabi splitting of 80 meV. Furthermore, by measuring power-dependent emission spectra, an equally high vacuum Rabi splitting value is extrapolated. Spectrally-resolved lifetimes reveal that the lower polariton state and uncoupled quantum dots exhibit equivalent decay times, consistent with surface plasmons strongly coupled to emitters. These results show that colloidal quantum dots are a viable and versatile optically active material for the study of strong light-matter coupling and its applications.
4:30 AM - GG4.02
Design of Efficient Light-Absorption Layers with Earth-Abundant Materials: A Tight-Binding Study on Inter-Band Transition Rate of Si:P Quantum Dots
KyuNam Cho 2 Chang-Sung Jeong 2 Hoon Ryu 1
1Korea Institute of Science and Technology Information Daejeon Korea (the Republic of)2Korea University Seoul Korea (the Republic of)Show Abstract
Photovoltaic (PV) devices have been extensively studied for applications in solar cells. However, the grid-parity of solar powers is not yet achieved due to the expensive cost of electricity compared to the cost with fossil fuels . Designs of highly efficient light absorption layers with earth-abundant materials, is thus critical as they can reduce the cost of PV cells by increasing the power-per-unit-area of solar panels. In consequence, optical properties of various materials and structures have been the central topic for research in nanoelectronics. III-V semiconductors have been known as excellent materials for light absorption layers. In particular, InAs/GaAs quantum dots (QDs) have been great interest to researchers as they exhibit high efficiency in light absorption, and have tunable optical gaps . But the expensive material cost becomes the limiting factor for the grid-parity. Earth-abundant materials such as Iron disulphide and Tin monosulphide have been studied due to their appropriate optical gaps , but the strong surface-recombination limits the device performance.
The combination of scanning tunneling microscope lithography and molecular beam epitaxy enabled a precise control of dopant placements in silicon (Si), a representative earth-abundant material. Various phosphorus (P) monolayer devices embedded in Si (Si:P) thus have been realized with the atomically precise incorporation of dopants, including planar electrodes, ultra-thin interconnects and donor-based QDs for advanced logic applications [5-7]. In this work, we expand the application scope of Si:P devices to optoelectronics with a focus on Si:P QDs. Electronic structures are calculated with the sp3d5s* tight-binding model that has shown its validity in describing Si:P devices [5-7]. We report promising properties of Si:P QDs as light absorption layers, particularly against self-assembled InAs/GaAs QDs: (I) The optical gap of single-dopant QDs is good for absorbing the natural light at ~1100um wavelengths, and is widely tunable by changing the number of P atoms in the dopant cluster. (II) The inter-band optical transition rate is much more insensitive to directions of polarization, which represents the strong potential of Si:P QDs in efficient absorption of the natural light injected from arbitrary directions. Establishing a theoretical framework of optical properties of Si:P QDs that have been rarely explored for realistically sized devices with a full atomistic model, this work presents a detailed analysis useful for potential designs of light absorption layers with Si:P QDs.
 M. Bazillan et al., Renewable Energy 53, 329 (2013)
 D. Forbes et al., Proceedings of SPIE (2014)
 P. Lazic et al., Journal of Physics: Condensed Matters 25, 465801 (2013)
 P. Sinsermsuksakul et al., Applied Physics Letters 102, 053901 (2013)
 H. Ryu et al., Nanoscale 8, 053901 (2013)
 H. Ryu et al., Small 11, 374 (2014)
 H. Ryu et al., Nano Letters 15, 450 (2015)
4:45 AM - GG4.03
Solution-Processed Vertical-Cavity Surface-Emitting All-Colloidal Quantum Dot Lasers
Burak Guzelturk 1 Yusuf Kelestemur 1 Kivanc Gungor 1 Aydan Yeltik 1 Mehmet Zafer Akgul 1 Wang Yue 2 Rui Chen 2 Cuong Dang 2 Handong Sun 2 Hilmi Volkan Demir 1 2
1Bilkent University Ankara Turkey2Nanyang Technological University Singapore SingaporeShow Abstract
Colloidal quantum dots (QDs) are highly attractive materials for full-color and solution-processed lasers. However, optical gain in these QDs has been severely limited due to nonradiative Auger recombination. To date, large-sized heterostructured nanocrystals including giant-QDs  and dot-in-rod type nanocrystals  have been shown to suppress Auger recombination. However, strongly reduced electron-hole overlap in such nanocrystals results in decreased oscillator strength and lower optical gain coefficients.
In this work, we proposed and developed core/shell CdSe/CdS QDs that simultaneously combine large oscillator strengths and increased optical gain coefficients and demonstrated high performance lasing using these tailor-made QDs incorporated into a colloidal optical cavity to achieve the first fully solution-processed vertical-cavity surface-emitting all-colloidal lasers (VCSEL) . To this end, we synthesized core/shell QDs having relatively a small size (with a total diameter of 8 nm) exhibiting polytypic crystal structure. The shell growth was performed at 310°C, which facilitated the formation of an alloyed soft-interface between the core and the shell as verified by careful XPS analysis . Through excitation intensity-dependent time-resolved fluorescence spectroscopy, we found that these alloyed core/shell QDs exhibit significantly suppressed Auger lifetime of 1.48 ns, which is similar to that of the giant-QDs and nanorods .
As a major advancement, here we achieved ultralow threshold and extremely stable optical gain using these engineered QDs. Single-photon absorption pumped amplified spontaneous emission (ASE) was achieved with an ultralow threshold of 29 µJ/cm2, and two-photon absorption pumped ASE threshold was measured to be 5 mJ/cm2, both of which set the records in their class for the colloidal QDs . This exceptionally efficient optical gain enabled us to realize the first all-colloidal lasers. For this, we developed an optical cavity using distributed Bragg reflectors (DBRs) obtained via alternative spin coating of the colloidal SiO2 and TiO2 nanoparticles. This all-colloidal laser showed remarkable two-photon absorption pumped lasing threshold as low as 730 µJ/cm2 . To the best of our knowledge, this is the best among all solution-processed semiconductors including organic molecules, conjugated polymers, nanorods, etc., reported to date .
These VCSELs demonstrated using tailor-made core/shell QDs coupled in a colloidal cavity in this work represent the first account of an all-colloidal laser based on a highly versatile and all-solution-processed approach, paving the way towards full-color, single-material laser arrays.
 F. García-Santamaría et al. Nano Lett 9, 3482 (2009).
 M. Zavelani-Rossi et al. Nano Lett 10, 3142 (2010).
 B. Guzelturk et al. Adv. Mater 27, 2742 (2015).
 V. Klimov et al. Science 287, 1011 (2000).
 C. Bauer et al. Adv. Mater. 14, 673 (2002), G. Xing et al. ACS Nano 6, 10835 (2012).
5:00 AM - GG4.04
Long Range Order in Square PbSe Quantum Dot Solids Mediated by Thickness and Atomic Connectivity
Ben Savitzky 1 Robert Hovden 1 Kevin Whitham 1 Tobias Hanrath 1 Lena F Kourkoutis 1
1Cornell University Ithaca United StatesShow Abstract
Quantum dot solids (QDS), in which semiconductor nanocrystals (NC) are arranged into two- or three-dimensional superlattices (SL), have drawn significant attention due to their highly tunable electronic band structures, yielding a wealth of potential applications in electronics and optoelectronics. Recently demonstrated atomically coherent interfaces across adjacent NCs represent a major stride towards achieving efficient electronic transport, a key challenge in QDS . However bringing this system to maturity will require understanding the relationships between structure at the scale of atoms, NCs, and SL grains. We find that the degree of atomic connectivity can be directly related to disorder in the NC-NC spacing. Further, we find that long range order (LRO) is improved by a narrower distribution in inter-NC spacing, and that LRO improves with increasing film thickness.
We study a square SL of connected 6-7 nm PbSe NCs with grains as large as 3 um, fabricated via self-assembly at a liquid-liquid interface. Using atomic-resolution aberration-corrected STEM over large fields of view, spanning entire NC SL grains, we analyzed order at multiple length scales. Quantitative analysis of LRO was achieved using the pair correlation function g(r), which describes the probability of finding two NC centers at a distance r apart. We show that the structure of g(r) closely matches a paracrystal model, in which disorder between NCs is allowed to propagate through the lattice, and that the distribution of inter-NC spacings narrows with increasing film thickness. Decline in LRO appears to result from the propagation of atomic-scale disorder in the inter-NC spacing through the SL. In thinner SLs greater disorder in NC-NC spacing causes faster loss of LRO. In thicker samples, LRO is preserved out to hundreds of nm.
To understand the source of the short-range NC-NC positional disorder we analyzed monolayer PbSe NC SLs, which grew smaller grains and displayed greater disorder in inter-NC spacing, consistent with the prior conclusion that LRO reduces in thinner samples. We show that the presence or absence of a continuous atomic lattice connecting two adjacent NCs directly impacts the NC-NC spacing, with unconnected adjacent NCs 8.0 Å farther apart on average than connected NCs. Comparison of monolayer and multilayer data suggests that the reduction of grain size and LRO in monolayer SLs is a result of reduced NC-NC connectivity.
 M.P. Boneschanscher et al., Science344 (2014), 1377-1380
 BHS acknowledges support from the NSF IGERT (DGE-0903653). This work was supported by the CCMR with funding from the NSF MRSEC program (DMR-1120296)
5:15 AM - GG4.05
Electron Transfer between Semiconductor Quantum Dots and Phthalocyanine
Maedeh Arvani 1 2 Kirsi Virkki 1 Alexander Efimov 1 Nikolai Tkachenko 1 Donald Lupo 1
1Tampere University of Technology Tampere Finland2Aring;bo Akademi University Turku FinlandShow Abstract
In the present work, electron and energy transfer in five different size quantum dots (QD) and phthalocyanine (Pc) hybrids are studied. QDs of five sizes with diameter in the range 2.8-5.3 nm were employed.
Organic-semiconductor hybrids have gained new attention after the invention of the quantum dots.   A combination of QDs and phthalocyanine offer interesting component structures. The absorption and emission of QDs as well as their other electronic properties depend on the size. For studied Pc, the absorption spectra of QD-Pc hybrids show Pc aggregation for 3 or more Pc per each QD. Adding different concentration of Pc from 1 Pc per 1 QD to 10 Pc per 1 QD resulted in gradual quenching of the QD emission although the position and shape of the band remain the same. This behavior indicates electron or energy transfer between QD and Pc.
Time-correlated single photon counting method was used to find the lifetimes of the pure QD and Pc samples and QD-Pc hybrids. The excitation wavelength was 483 nm for all hybrid samples which means that QDs were excited. The TCSPC measurements show reduction of the emission lifetime by adding Pc to QDs in agreement with QD steady state emission quench. Transient absorption spectroscopy (pump-probe method)  was also used to investigate electron and energy transfer in QD-Pc (1:7) hybrids. The concentration of Pc was high enough to cause at least 60% quenching of the QD emission in QD-Pc complex, typically QD:Pc = 1:7, although absorption spectra showed Pc aggregation in such a high concentration of Pc. There was no change in absorption spectrum of the samples after the measurements, indicating high photo-stability. The results show the average time constant of band formation at 650 nm is larger for larger QDs. On the other hand, the overlap of emission spectra of QDs with absorption spectra of Pc is larger for larger QDs. The combination of the transient absorption spectra and absorption and emission spectra measurement indicate an electron transfer between QD and Pc.  
1- Recent Advances in Quantum Dot Surface Chemistry (Douglas, 2014, 3041minus;3057)
2-Competition between Energy and Electron Transfer from CdSe QDs to Adsorbed Rhodamine B. (Abdelaziz Boulesbaa, 2010, 962-969)
3-Role of the Bridge in Photoinduced Electron Transfer in Porphyrin-Fullerene Dyads. (Beatriz Pelado, 2015, 5814-5825)
4-Photoinduced electron transfer of double-bridged phthalocyanine-fullerene dyads. ( Marja Isosomppia, 2006, 36-40)
5-the Quenching of CdSe Quantum Dots Photoluminescence by Gold Nanoparticles in Solution. ( Babak Nikoobakht, 2002, 591-597)
5:30 AM - GG4.06
Overcoating Alloyed InPZnS Quantum Dots for Record High Quantum Efficiency and Narrow Size Distribution through Optimized Precursor Concentration
Evren Mutlugun 1 Yemliha Altintas 1 Mohammad Younis Talpur 1 Miray Unlu 1
1Abdullah Gul University Kayseri TurkeyShow Abstract
Cd-free colloidal quantum dots hold great promise for future optoelectonic devices and applications. InP based quantum dots, have been under investigation regarding their potential for high efficiency, color tunability and narrow size distribution. However these quantum dots suffer from surface defects which decrease their emission quantum yield, limiting their use as compared to Cd-based counterparts.
In this work, we demonstrate the synthesis of alloyed InPZnS quantum dots further overcoated with wider band gap ZnS shell which has shown remarkable quantum yield values up to 80% preserving their full-width-half-maximum value as narrow as 45 nm. The effects of different precursor concentrations of tris(trimethylsilyl) phosphine, 1-dodecanethiol, myristic acid (MA) and the ratio of In/P and In/MA were investigated. The various core growth temperatures by alternative method using indium chloride, stearic acid, hexdecylamine, cyclohexyl isothiocyanate and zinc undecylenate has been studied. The extensive optimization study of the fatty acid ligands, the precursors, the nucleation and growh temperature of the InP based nanocrystals have been investigated to possess high quantum yield along with the color tunability and narrow size distribution. The realization of the ratio of the precursors under consideration and study of the overcoating of ZnS material has been investigated for the engineering of high efficiency quantum dots with emission peak varied from blue to near infrared, namely from 480 nm to 650 nm. The results hold great promise for future white light generation, based on pure emitting nanoluminophores, achieving enhanced color gamut.
5:45 AM - GG4.07
Extracting g Tensor Values from Experimental Data with Markov Chain Monte Carlo Methods
Anagha Shashishekhar Kulkarni 1 Matthew Doty 2
1University of Delaware Newark United States2University of Delaware Newark United StatesShow Abstract
Quantum Dots (QDs) have long been of interest as platforms for optoelectronic quantum sensing, quantum information processing (QIP) and quantum communications. Self assembled Indium Arsenide QDs, in particular, are of interest because they can confine single charges with well-defined spin projections that have long coherence times, and the QDs have large dipole matrix elements that allow easy coupling to optical fields. In recent years Quantum Dot Molecules (QDMs) have emerged as a new platform for optoelectronic device technologies. QDMs consist of multiple QDs arranged in sufficiently close spatial proximity such that interactions between the QDs can be used to tailor both optical and spin properties. Not only can these properties be tailored during growth, they can also be tuned in-situ by applying electric fields that vary the coupling between QDs, which controls the formation of delocalized molecular-like states. In this sense, QDMs provide a solid-state analog of molecular engineering in which the controlled formation of molecular states can be used to achieve new electronic and spintronic functionality not available with individual QD “atoms.”
Using molecular engineering approaches to tailor QDMs for specific optoelectronic or spintronic applications requires precise knowledge of specific parameters such as the binding energies of excitonic and biexcitonic charge complexes, the magnitude of many body coulomb interactions under varying spatial distributions of charge or the individual components of the g tensor for single electrons or holes. However, these parameters often appear in experimental spectra as sums and differences and it can be extremely difficult to extract precise values from either experimental measurements or theoretical calculations. We develop and apply a Markov Chain Monte Carlo method for extracting precise values for physical parameters from photoluminescence (PL) data. We demonstrate this approach by extracting elements of the g tensor for a single hole confined in an InAs QDM from PL obtained as a function of applied electric and magnetic fields. The extracted values provide critical information for the design of quantum structures tailored for optoelectronic and spintronic device applications. The approach can be applied to extract, precise quantitative values for many other important physical parameters from sparse experimental data on a variety of systems.
GG5: Poster Session I: Emerging Materials and Platforms for Optoelectronics I
Monday PM, November 30, 2015
Hynes, Level 1, Hall B
9:00 AM - GG5.01
Processing of Semiconductor Core Optical Fiber for Mid IR Wavelength Transmission
Mustafa Ordu 1 Jicheng Guo 2 James Bird 1 2 Siddharth Ramachandran 3 2 Soumendra N. Basu 1 2
1Boston University Boston United States2Boston University Boston United States3Boston University Boston United StatesShow Abstract
Semiconductor core optical fibers allow low loss mid-IR transmission enabling various applications such as remote IR laser delivery and chemical sensing. Ge core optical fiber with borosilicate glass cladding is fabricated by conventional fiber drawing technique. Ge rods are placed in borosilicate glass tubes and placing additional borosilicate glass tubes concentrically increases the cladding diameter. This study examines the Rayleigh instability of the Ge cores as a function of core diameter, draw temperature and draw velocity.
9:00 AM - GG5.03
Hierarchically Designed ZnO Nanowire Arrays on Si Honeycomb Structures for Highly Efficient Omnidirectional and Flexible Photodetectors
Seongdong Lim 1 Doo-Seung Um 1 Minjeong Ha 1 Youngsu Lee 1 Hyunhyub Ko 1
1Ulsan National Institute of Science and Technology (UNIST) Ulsan Korea (the Republic of)Show Abstract
The photon management technique is a key issue for high performance optoelectronics including photodetectors, light-emitting diodes, and solar cells. In order to effectively collect omnidirectional light, low-refractive index antireflection coating or antireflective nanostructures are introduced onto the surface of optoelectronics. Beside, hierarchically designed micro/nanostructures can enhance the light absorption efficiency via efficient light absorption and management behavior. In addition, flexibility in photodetectors have been an issue for their potential applications in flexible image sensor, artificial retina, and curved display.
In this study, we introduce a hierarchically designed ZnO nanowire (NW) arrays on Si honeycomb heterostructures for the development of highly efficient omnidirectional and flexible photodetectors with broad spectral range from UV to NIR. The honeycomb-structured free-standing silicon membrane can be attached onto the flexible polyimide substrate, which enables high flexibility without loss of photoresponsivity. To demonstrate the omnidirectional light absorption of honeycomb structures, we perform a UV-Vis-NIR analysis with variable angle specular reflectance accessory (VASRA). We confirm that the growth of ZnO NW arrays onto honeycomb structured Si membrane diminishes the light reflection mainly due to the efficient light absorption by the hierarchical micro/nanostructures. The angle-dependent photoresponsivity and VASRA analysis of our photodetectors indicate that the combination of honeycomb-structured Si membranes and ZnO NWs has substantially increased the omnidirectional property. We anticipate that the omnidirectional light absorption property of our hierarchical structures can be utilized to future energy-harvesting and flexible optoelectronic devices.
9:00 AM - GG5.04
Organic Down-Converter Molecules for White Light Emission
Neil Findlay 1 Jochen Bruckbauer 1 R.W. Martin 1 Peter J. Skabara 1
1Univ of Strathclyde Glasgow United KingdomShow Abstract
Solid state lighting using light emitting diodes composed of III-nitride systems are readily available and have already been commercialised; however, there is still scope for improved wavelength converters to provide further advances in terms of cost and energy efficiency. Although there are several ways of producing white light, one approach is the combination of a blue inorganic LED together with a yellow emitting phosphor layer that not only transmits a fraction of the blue light, but absorbs and converts the remaining blue light to lower energy yellow light, providing a broad spectrum of white emission. Such an approach is readily employed in commercially available LEDs today.
Here we present our hybrid approach to generating broad spectrum white light from a combination of well-studied GaN blue LEDs and novel, organic down-converter molecules. Our hypothesis, to bond a blue, absorbing component with a yellow emissive component, has been to shown to effectively provide white light using an encapsulated down-conversion layer, with CIE coordinates of (0.34, 0.31) and a CCT of 5137 K. Synthetic procedures and studies towards qualifying the quality of light produced will be disclosed. Our early studies on the emissive component will additionally be discussed, together with more recent efforts towards the next generation of systems that will enable white light emission from these hybrid device architectures.
1. N. J. Findlay, C. Orofino-Peña, J. Bruckbauer, S. E. T. Elmasly, S. Arumugam, A. R. Inigo, A. L. Kanibolotsky, R. W. Martin, P. J. Skabara, J. Mater. Chem.2013, 1, 2249-2256.
2. N. J. Findlay, J. Bruckbauer, A. R. Inigo, B. Breig, S. Arumugam, D. J. Wallis, R. W. Martin, P. J. Skabara, Adv. Mater.2014, 26, 7290-7294.
9:00 AM - GG5.05
Carbon-Based Hybrid Flexible Photodetector Array Functionalized with a Ruthenium Complex
Eun Kwang Lee 1 2 Xien Liu 1 Dong Yeong Kim 1 Cheol Hee Park 2 Joon Hak Oh 2
1UNIST Ulsan Korea (the Republic of)2POSTECH Pohang-si Korea (the Republic of)Show Abstract
The rapid development of field-effect transistors (FETs) based on graphene and organic semiconductor (OSC) has advanced multi-functional optoelectronic devices, such as photodetectors, light-emitting transistors, photo-controlled memories, etc. The charge transport properties of these optoelectronic devices can be manipulated not only by applying gate bias, but also by changing the intensity of incident light. Photodetectors based on graphene and OSC combine light detection and signal amplification in a single device and have many advantages, such as mechanical flexibility, low-cost fabrication process, and large-scale production. However, graphene and OSC typically have low light absorption for high performance of photodetectors. In this study, a newly synthesized ruthenium complex (Ru-complex) has been applied to the graphene and N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI, as OSC) FETs via a simple solution method. By way of the functionalization of a Ru-complex on those materials, the performance of these photodetectors has been improved greatly due to the metal-ligand charge transfer (MLCT). The fabricated photodetectors have been integrated into array system on plastic substrates, which show high mechanical flexibility and stable operation after repeated bending tests under tensile and compressive strains. Our study paves a simple and viable way to improve photoresponsivity of carbon-based materials such as graphene and OSC for the application of smart optoelectronic devices.
9:00 AM - GG5.06
High Efficient Organic Optoelectronic Device with Dual Functions of Ultraviolet Photodetection and Electroluminescence Consisting of a Charge-Transfer-Featured Naphthalimide Derivative
Hanyu Wang 1 Jie Zhou 2 Xu Wang 1 Zhiyun Lu 2 Junsheng Yu 1
1University of Electronic Science and Technology of China Chengdu China2College of Chemistry, Sichuan University Chengdu ChinaShow Abstract
Organic photoelectronics have been of much interest in recent years with the merits of low cost, light-weight, high flexibility and versatility of chemical structures. The representative devices for organic photoelectronic technology are organic light-emitting diodes (OLEDs), organic ultraviolet photodetectors (UV-PDs), organic solar cells, organic photovoltaic and electroluminescent (EL) integrated devices, et al. Among them, OLEDs are attractive in the fields of solid-state lighting and full-color displays. Meanwhile, lots of work has been focused on organic UV-PDs owing to their wide application in fields like solar astronomy, fire detection, biological sensing, and so on. Noteworthily, even though an integrated device with multi-function as an organic UV-PD and OLED is important