One‐Step Blade‐Coated Highly Efficient Nonfullerene Organic Solar Cells with a Self‐Assembled Interfacial Layer Enabled by Solvent Vapor Annealing

A pronounced enhancement of the power conversion efficiency (PCE) by 38% is achieved in one-step doctor-blade printing organic solar cells (OSCs) via a simple solvent vapor annealing (SVA) step. The organic blend composed of a donor polymer, a nonfullerene acceptor, and an interfacial layer (IL) molecular component is found to phase-separate vertically when exposed to a solvent vapor-saturated atmosphere. Remarkably, the spontaneous formation of a fine, self-organized IL between the bulk heterojunction (BHJ) layer and the indium tin oxide (ITO) electrode facilitated by SVA yields solar cells with a significantly higher PCE (11.14%) than in control devices (8.05%) without SVA and in devices (10.06%) made with the more complex two-step doctor-blade printing method. The stratified nature of the ITO/IL/BHJ/cathode is corroborated by a range of complementary characterization techniques including surface energy, cross-sectional scanning electron microscopy, grazing incidence wide angle X-ray scattering, and X-ray photoelectron spectroscopy. This study demonstrates that a spontaneously formed IL with SVA treatment combines simplicity and precision with high device performance, thus making it attractive for large-area manufacturing of next-generation OSCs. Funding Agencies|NSFCNational Natural Science Foundation of China (NSFC) [61774077, 61274062, 11204106]; Guangzhou Science and Technology Plan Project [201804010295]; Research and Development Program in Key Areas of Guangdong Province [2019B090921002]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities; Sunflare Institute of Solar Energy, Jinan University; Swedish Government Research Area in Materials Science on Functional Materials at Linkoping University [200900971]; Jinan UniversityJinan University; King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) [OSR-2018-CARF/CCF-3079]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; National Science FoundationNational Science Foundation (NSF) [DMR-1332208]