High-efficiency ternary polymer solar cells with optimized morphology of active layers enabled by few-layered β-InSe nanosheets

Due to the excellent electrical and optical properties, few-layered β-indium selenide (InSe) nanosheets are successfully introduced into the active layer of polymer solar cells (PSCs) as the third component for the first time. The addition of few-layered β-InSe nanosheets optimizes the absorption, crystallinity and vertical component distribution of the active layer. Compared with the binary devices, the ternary devices exhibit optimized bulk morphology and reduced charge recombination. The power conversion efficiency (PCE) of PSCs based on the PM6 : Y6 system is obviously improved from 15.02% to 16.56% due to the increasing short-circuit current and fill factor. The mechanism accounting for the morphological change in the ternary active layer is investigated in depth. Moreover, the efficacy of β-InSe in long-term stability and other active layer systems of PSCs is confirmed. Therefore, this work demonstrates that few-layered β-InSe has bright prospects in photovoltaic devices.