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. [ABSTRACT FROM AUTHOR]