Overcoming Interfacial Losses in Solution‐Processed Organic Multi‐Junction Solar Cells |
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Authors: | Xiaoyan Du Ole Lytken Manuela S. Killian Jiamin Cao Tobias Stubhan Mathieu Turbiez Patrik Schmuki Hans‐Peter Steinrück Liming Ding Rainer H. Fink Ning Li Christoph J. Brabec |
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Affiliation: | 1. Physical Chemistry 2 and ICMM, Department of Chemistry and Pharmacy, Friedrich‐Alexander‐University Erlangen‐Nürnberg (FAU), Erlangen, Germany;2. Department of Materials Science, LKO, Friedrich‐Alexander‐University Erlangen‐Nürnberg (FAU), Erlangen, Germany;3. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, China;4. Institute of Materials for Electronics and Energy Technology (i‐MEET), Friedrich‐Alexander‐University Erlangen‐Nürnberg (FAU), Erlangen, Germany;5. BASF Schweiz AG, Basel, Switzerland;6. Department of Chemistry, King Abdulaziz University, Jeddah, Saudi Arabia;7. Bavarian Center for Applied Energy Research (ZAE Bayern), Erlangen, Germany |
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Abstract: | Organic solar cells are promising in terms of full‐solution‐processing which enables low‐cost and large‐scale fabrication. While single‐junction solar cells have seen a boost in power conversion efficiency (PCE), multi‐junction solar cells are promising to further enhance the PCE. In all‐solution‐processed multi‐junction solar cells, interfacial losses are often encountered between hole‐transporting layer (HTL) and the active layers and therefore greatly limit the application of newly developed high‐performance donor and acceptor materials in multi‐junction solar cells. Here, the authors report on a systematic study of interface losses in both single‐junction and multi‐junction solar cells based on representative polymer donors and HTLs using electron spectroscopy and time‐of‐flight secondary ion mass spectrometry. It is found that a facile mixed HTL containing poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and MoO x nanoparticles successfully overcomes the interfacial losses in both single‐ and multi‐junction solar cells based on various active layers by reducing interface protonation, promoting better energy‐level alignment, and forming a dense and smooth layer. Solution‐processed single‐junction solar cells are demonstrated to reach the same performance as with evaporated MoO x (over 7%). Multi‐junction solar cells with polymers containing nitrogen atoms as the first layer and the mixed PEDOT:PSS and MoO x nanoparticles as hole extraction layer reach fill factor (FF) of over 60%, and PCE of over 8%, while the identical stack with pristine PEDOT:PSS or MoO x nanoparticles show FF smaller than 50% and PCE less than 5%. |
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Keywords: | interfacial losses organic multi‐junction solar cells organic photovoltaics recombination layer solution‐processing |
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