Available on-demand - F.SF04.01.14
Late News: Hydroresistive Flexible Organic Molecular Metal
Raphael Pfattner1,2,Victor Lebedev1,Elena Laukhina2,Marta Mas-Torrent1,2,Vladimir Laukhin1,3,Concepcio Rovira1,2,Jaume Veciana1,2
Materials Science Institute of Barcelona (ICMAB-CSIC)1,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)2,Institucio Catalana de Recerca i Estudis Avancats (ICREA)3
Show Abstract
The first [BEDT-TTF = bis(ethylenedithio)- tetrathiafulvalene based quasi-twodimensional organic superconductor β-(BEDT-TTF)2I3 was first reported back in 1984.[1] Soon it became clear that ion radical salts (IRSs) derived from BEDT-TTF exhibit tuneable electronic band structures; therefore, such molecules are excellent building blocks for engineering a rich and diverse family of organic crystalline metals and semiconductors. Electronic band structures of BEDT-TTF-based molecular conductors originate from ordered arrangements, such as stacks and layers, leading to metallic charge-transfer salts with partially filled bands.[2]
One interesting characteristic of BEDT-TTF-based crystalline conductors is the very deformable molecular and crystal structure with strong electron−electron and electron−phonon couplings. Thanks to this, their anisotropic electronic structures exhibit many fascinating electronic and structural phase transitions caused by lattice deformations, which can be controlled by external stimuli such as light, temperature, strain, pressure, and humidity, among others. Nevertheless, it is necessary to engineer these crystals into a proper material for sensing applications. This was done by forming polycrystalline layers of IRSs, derived from BEDTTTF-based conductors, in nanocomposite bilayer (BL) films a strategy that allows combining electrical properties of IRSs with classical properties of insulating polymers, like flexibility, transparency, and solution processability.
Developing smart materials that can respond to an external stimulus is of major interest in artificial sensing devices able to read information about the physical, chemical and/or biological changes produced in our environment. Additionally, if these materials can be deposited or integrated on flexible, transparent substrates, their appeal is greatly increased. Such properties can be further tuned by choosing the nature of the IRSs enabling high sensitivity towards strain, pressure, temperature or even contactless radiation sensing i.e. bolometers.[3,4] In a very recent example, bilayer films, composed of conducting polycrystalline layers of two dimensional BEDT-TTF-IRSs, hydroresistive sub-micron sized crystals on top of a polymeric host matrix permit to electrically monitor relative humidity in a stable and fully reversible fashion.[5] This sensor platform enables the combination of high electrical performance of single crystals with processing properties of polymers towards a simple, low-cost and highly sensitive platform for applications in robotics, biomedicine and human health care.
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[2] J. M. Williams, J. R. Ferraro, R. J. Thorn, K. D. Carlson, U. Geiser, H. H. Wang, A. M. Kini, M.-H. Whangbo, Organic Superconductors
(Including Fullerenes): Synthesis, Structure, Properties and Theory; Prentice Hall: Englewood Cliffs, NJ, 1992.
[3] E. Laukhina, R. Pfattner, L. R. Ferreras, S. Galli, M. Mas-Torrent, N. Masciocchi, V. Laukhin, C. Rovira, J. Veciana. Advanced Materials,
2009, 21, 1-5.
[4] R. Pfattner, V. Lebedev, E. Laukhina, S. Chaitanya Kumar, A. Esteban-Martin, V. Ramaiah-Badarla, M. Ebrahim-Zadeh, F. Pelayo García
de Arquer, G. Konstantatos, V. Laukhin, C. Rovira, J. Veciana. Advanced Electronic Materials, 2015, 1, 1500090.
[5] R. Pfattner, E. Laukhina, L. Ferlauto, F. Liscio, S. Milita, A. Crespi, V. Lebedev, M. Mas-Torrent, V. Laukhin, C. Rovira, J. Veciana, ACS
Applied Electronic Materials 2019, 1, 1781.