Copper(I) Thiocyanate (CuSCN) Hole‐Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin‐Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells |
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| Authors: | Nilushi Wijeyasinghe Anna Regoutz Flurin Eisner Tian Du Leonidas Tsetseris Yen‐Hung Lin Hendrik Faber Pichaya Pattanasattayavong Jinhua Li Feng Yan Martyn A. McLachlan David J. Payne Martin Heeney Thomas D. Anthopoulos |
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| Affiliation: | 1. Department of Physics and The Centre for Plastic Electronics, Imperial College London, London, UK;2. Department of Materials and The Centre for Plastic Electronics, Imperial College London, Royal School of Mines, London, UK;3. Department of Physics, National Technical University of Athens, Athens, Greece;4. Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand;5. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong;6. Department of Chemistry and The Centre for Plastic Electronics, Imperial College London, London, UK;7. Materials Science and Engineering, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia |
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| Abstract: | This study reports the development of copper(I) thiocyanate (CuSCN) hole‐transport layers (HTLs) processed from aqueous ammonia as a novel alternative to conventional n‐alkyl sulfide solvents. Wide bandgap (3.4–3.9 eV) and ultrathin (3–5 nm) layers of CuSCN are formed when the aqueous CuSCN–ammine complex solution is spin‐cast in air and annealed at 100 °C. X‐ray photoelectron spectroscopy confirms the high compositional purity of the formed CuSCN layers, while the high‐resolution valence band spectra agree with first‐principles calculations. Study of the hole‐transport properties using field‐effect transistor measurements reveals that the aqueous‐processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl sulfide solutions with the maximum values approaching 0.1 cm2 V?1 s?1. A further interesting characteristic is the low surface roughness of the resulting CuSCN layers, which in the case of solar cells helps to planarize the indium tin oxide anode. Organic bulk heterojunction and planar organometal halide perovskite solar cells based on aqueous‐processed CuSCN HTLs yield power conversion efficiency of 10.7% and 17.5%, respectively. Importantly, aqueous‐processed CuSCN‐based cells consistently outperform devices based on poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate HTLs. This is the first report on CuSCN films and devices processed via an aqueous‐based synthetic route that is compatible with high‐throughput manufacturing and paves the way for further developments. |
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| Keywords: | copper(I) thiocyanate hole‐transport layers organic solar cells perovskite solar cells transparent semiconductors and transistors |
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