High-Mobility and Bias-Stable Field-Effect Transistors Based on Lead-Free Formamidinium Tin Iodide Perovskites

Electronic devices based on tin halide perovskites often exhibit a poor operational stability. Here, we report an additive engineering strategy to realize high-performance and stable field-effect transistors (FETs) based on 3D formamidinium tin iodide (FASnI(3)) films. By comparatively studying the modification effects of two additives, i.e., phenethyl-ammonium iodide and 4-fluoro-phenyl-ethyl-ammonium iodide via combined experimental and theoretical investigations, we unambiguously point out the general effects of phenethyl-ammonium (PEA) and its fluorinated derivative (FPEA) in enhancing crystallization of FASnI(3) films and the unique role of fluorination in reducing structural defects, suppressing oxidation of Sn2+ and blocking oxygen and water involved defect reactions. The optimized FPEA-modified FASnI(3) FETs reach a record high field-effect mobility of 15.1 cm(2)/(V center dot s) while showing negligible hysteresis. The devices exhibit less than 10% and 3% current variation during over 2 h continuous bias stressing and 4200-cycle switching test, respectively, representing the best stability achieved so far for all Sn-based FETs.