Suppressing Interfacial Contact Energetics with Ultrathin Organic Passivation in Hysteresis-Free Lead-Halide Perovskite Transistors

Recent years have seen considerable efforts dedicated to perovskite field-effect transistors driven by the ability to favorably modulate microstructural properties and device performance through interface and additive engineering. However, metal halide perovskite semiconductors typically exhibit structural disorders at grain boundaries and ionic defects. In this study, we demonstrate that surface passivation with an ultrathin organic semiconductor can effectively suppress interfacial contact energetics at the perovskite-metal contact electrode interface in lead halide perovskite transistors without adversely affecting film crystallinity. Our ultrathin organic surface-passivated methylammonium lead iodide (MAPbI₃) perovskite field-effect transistors exhibit stable repeated measurement cycles with an electron mobility enhancement exceeding 100% compared to unpassivated control devices. Chemical and structural investigations revealed that the diluted, solution-processed organic semiconductors integrate within the grain boundaries. This integration results in improved perovskite film crystallinity, enhanced injection properties, and effective passivation of surface defects at the metal-perovskite interface. These findings are supported by photoluminescence, X-ray, and ultraviolet photoelectron spectroscopy measurements. This study advances the understanding of contact reaction-induced defects and operational instabilities in lead halide perovskite field-effect transistors and related devices.