Abstract Tin (Sn2+)‐based halide perovskites have been developed as the most promising alternatives to their toxic Pb‐based counterparts in optoelectronic devices. However, the facile tin vacancy formation and easy oxidization characteristics make Sn2+‐based perovskites highly p‐doped with excessive hole concentrations, which significantly hinder their applications. Herein, we demonstrate a potent hole inhibitor of antimony fluoride (SbF3), which possesses a higher hole‐suppression capability than conventional tin fluoride (SnF2). A small amount of SbF3 allows a wide range of hole‐density modulation with no or less SnF2 addition, thus mitigating the negative effects of using only SnF2. A SnF2/SbF3 co‐additive approach was further developed to achieve high‐performance Sn2+ perovskite thin‐film transistors operated in the enhancement mode with a five‐fold enhancement of the field‐effect mobility and improved operational stability compared to using only SnF2. We expect that the SbF3 hole suppressor and co‐additive approach can provide opportunities for the development of high‐efficiency Sn2+‐perovskite optoelectronic devices.
