Tackling Energy Loss in Organic Solar Cells via Volatile Solid Additive Strategy

Abstract The energy loss induced open‐circuit voltage ( V OC ) deficit hampers the rapid development of state‐of‐the‐art organic solar cells (OSCs), therefore, it is extremely urgent to explore effective strategies to address this issue. Herein, a new volatile solid additive 1,4‐bis(iodomethyl)cyclohexane (DIMCH) featured with concentrated electrostatic potential distribution is utilized to act as a morphology‐directing guest to reduce energy loss in multiple state‐of‐art blend system, leading to one of highest efficiency (18.8%) at the forefront of reported binary OSCs. Volatile DIMCH decreases radiative/non‐radiative recombination induced energy loss (Δ E 2 /Δ E 3 ) by rationally balancing the crystallinity of donors and acceptors and realizing homogeneous network structure of crystal domain with reduced D–A phase separation during the film formation process and weakens energy disorder and trap density in OSCs. It is believed that this study brings not only a profound understanding of emerging volatile solid additives but also a new hope to further reduce energy loss and improve the performance of OSCs.