Regulating Growth Kinetics of Tin‐Based Perovskites via Ionic Liquid Additives for High‐Performance Field‐Effect Transistors

Tin-based perovskites have emerged as promising semiconductor materials for field-effect transistors channel layers. However, their rapid crystallization often causes low-quality films, and the challenge is further exacerbated due to thinner channel layers required in transistors. Here, ionic liquids are utilized with varying concentrations and coordination abilities to regulate the growth kinetics of perovskites. They serve a dual function, not only slowing the growth rate of tin-based perovskites but also simultaneously enhancing the number of nucleation sites. By balancing nucleation density and growth rate, smooth and pinhole-free films with preferred orientation are achieved, even from low-concentration precursor solutions. Optimized propylammonium acetate-incorporated transistors exhibit a maximum carrier mobility of 30.6 cm² V^-1 s^-1 with excellent operational stability, attributed to improved film quality and effective suppression of ion migration. This work provides novel insights into the critical role of ionic liquid additives in fabricating tin-based perovskites films, offering a promising route for perovskite transistors.