Highly stable inverted non-fullerene OSCs by surface modification of SnO2 with an easy-accessible material

Abstract In order to regulate the energy level of SnO2 films, we currently in this study employed a non-conjugated small molecule 2-(Dimethylamino) ethyl methacrylate (DMAEMA) to modify SnO2 films, which are applied as electron transportation layers in inverted non-fullerene organic solar cells (OSCs). It is demonstrated that an ultra-thin layer of DMAEMA can efficiently reduce the work function of SnO2 due to the formation of surface dipoles. The optimized PCE of OSCs based on photoactive materials PM6:Y6 increased from 13.80% to 15.45% after the SnO2 films being modified with DMAEMA. More importantly, the OSCs with DMAEMEA-modified SnO2 showed an extremely excellent stability, and the unencapsulated devices maintained 95% of the initial PCE after being stored in Nitrogen for 960 h. To the best of our knowledge, the average decay rate of normalized PCE is the smallest among the up-to-date reported studies.