Triphenylamine dibenzofulvene–derived dopant‐free hole transporting layer induces micrometer‐sized perovskite grains for highly efficient near 20% for p‐i‐n perovskite solar cells

This paper discusses a series of triphenylamine dibenzofulvene–based hole transporting materials (HTMs) featuring different numbers of MeO groups (none for YC‐1, four for YC‐2, and six for YC‐3) and their use in p‐i‐n perovskite solar cells (PSCs). We investigated the optoelectronic properties of these HTMs and found that the PSC devices incorporating YC‐1 as HTMs exhibited power conversion efficiencies (PCEs) of 15.78 ± 0.61%, which outperformed the corresponding PEDOT:PSS‐based device (12.80 ± 1.31%) under similar testing conditions. We then employed YC‐1 for the interfacial modified layer of a NiOx‐derived PSC having the structure ITO/NiOx/YC‐1/CH3NH3PbI3/PC61BM/bathocuproine/Ag. The presence of YC‐1 promoted the growth of micrometer‐sized grains of perovskite and induced a lower content of grain boundary defects, both of which improved the carrier extraction. Thereby, compared with conventional NiOx device, we observed a great increase in the PCE, from 17.16 ± 0.68% to 18.81 ± 0.42%, with a champion cell displaying a PCE of 19.37% (with negligible hysteresis). The corresponded device exhibited a stabilized efficiency of approximately 19% after storage in the dark at 25°C under argon for over 1000 hours. This study suggests a new approach for designing the high‐performance stable p‐i‐n PSCs. New triphenylamine dibenzofulvene‐derived HTMs were synthesized for p‐i‐n dopant‐free PSCs. The best device performance featured a PCE of 19.37%, with negligible hysteresis and approximately 19% after storage in the dark for over 1000 hours.