Improving Cathodes with a Polymer Interlayer in Reversed Organic Solar Cells |
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| Authors: | Zheng Tang Wolfgang Tress Qinye Bao Mohammad J Jafari Jonas Bergqvist Thomas Ederth Mats R Andersson Olle Inganäs |
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| Institution: | 1. Biomolecular and Organic Electronics, IFM and Center of Organic Electronics, Link?ping University, Link?ping, Sweden;2. Surface physics and chemistry, IFM, Link?ping University, Link?ping, Sweden;3. Molecular physics, IFM, Link?ping University, Link?ping, Sweden;4. Polymer Technology, Department of Chemical and Biological Engineering, Chalmers University of Technology, G?teborg, Sweden;5. Ian Wark Research Institute, University of South Australia, South Australia, Australia |
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| Abstract: | The effects of cathode modification by a conjugated polymer interlayer PFPA1 on the performance of reversed organic solar cells (substrate/cathode/active layer/transparent anode) based on different active material systems and different substrate electrodes are systematically investigated. A reduction of the work function irrespective of the substrate cathode used is observed upon the deposition of the PFPA1 interlayer, which is further related to an improved built‐in electric field and open‐circuit voltage. The amphiphilic character of the PFPA1 interlayer alters the surface energy of the substrate cathode, leading to the formation of a better active layer morphology aiding efficient exciton dissociation and photocurrent extraction in the modified solar cells. Hence, internal quantum efficiency is found to be significantly higher than that of their unmodified counterparts, while optically, the modified and unmodified solar cells are identical. Moreover, the deep highest occupied molecular orbital (HOMO) of the PFPA1 interlayer improves the selectivity for all investigated substrate cathodes, thus enhancing the fill factor. |
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| Keywords: | organic solar cells polymer solar cells interlayer modification interfaces selectivity |
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