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  Xu, J.; Heumüller, T.; Le Corre, V.M.; Barabash, A.; Félix, R.; Frisch, J.; Bär, M.; Brabec, C.J.: A polymer bilayer hole transporting layer architecture for high-efficiency and stable organic solar cells. Joule 8 (2024), p. 2570-2584

10.1016/j.joule.2024.06.013
Open Access Version

Abstract:
All-solution-processed organic photovoltaic (OPV) cells allow costand energy-effective fabrication methods for large-area devices. Despite significant progress on laboratory-scale devices, there is still a lack of interface materials that can be solution processed on top of the active layer, are compatible with novel non-fullerene acceptors (NFAs), and also provide sufficient long-term stability. We developed a novel interface layer concept, where alcohol-based organic polymer nanoparticles can be processed on top of a polymer- NFA active layer and doped to achieve a quasi-Ohmic hole contact. Moreover, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is processed as a second layer, forming a bilayer solution-processed hole transporting layer (HTL), providing an industrially relevant inverted architecture with a protective PEDOT:PSS layer on top. Most importantly, exceptional stability is observed. PM6:Y6 devices with the bilayer HTL are demonstrated to maintain 93% of their initial efficiency for 1,800 h under continuous solar cell operation at 60
C.