Non-volatile methylammonium chloride substitution for tin halide perovskite transistors

Abstract

Tin halide perovskites are a potential p-type channel material for thin-film transistors due to their high room-temperature hole mobility and easy processability. However, creating a high-quality thin film with a three-dimensional tin halide perovskite is challenging due to its inherent instability and defect density. Here we show that the coordinated control of A-site cations and X-site anions in a three-dimensional perovskite, formamidinium tin iodide (FASnI3), using methylammonium chloride (MACl) can stabilize the crystal structure. Unlike lead halide perovskites, where MACl functions only as a volatile intermediate-phase stabilizer, we show that MACl is incorporated into the FASnI3 crystal structure through the substitution of FA and I components with MA and Cl, which enhances its stability. The resulting uniform thin films offer improved crystallinity and larger grain sizes. A MACl-substituted FASnI3 transistor exhibits a field-effect hole mobility of over 80 cm2 V−1 s−1, an on/off current ratio over 3.0 × 109 and a threshold voltage of around 0 V, as well as high operational reliability and hysteresis-free behaviour.