Buried Interface Engineering via Homogenized Two-Dimensional Phase Enables High-Mobility Tin Perovskite Photosynaptic Transistor

Tin halide perovskites (THPs) possess remarkably high carrier mobility and absorption coefficient that make them attractive for photosynaptic transistors. However, uncontrollable crystallization kinetics induces 2D/3D phase inhomogeneity and orientation disorder in the perovskite film, ultimately compromising its interfacial quality and device performance. In this work, we address this issue by manipulating interfacial hydrogen bonding through urea modification on SiO 2 substrates, resulting in enhanced homogeneity of 2D perovskite phase within the film. Meanwhile, our strategy effectively improves the crystallographic orientation and suppresses defect formation (e.g., Sn 4+ ) toward the buried interface, leading to 5-fold enhancement in field-effect mobility of the transistor. The device exhibits synaptic behaviors under light illumination spanning from visible to near-infrared (NIR) wavelengths, demonstrating synaptic plasticity, paired-pulse facilitation, and learning-forgetting-relearning cycles. This study provides insights toward tailored design of crystallization for high-mobility THP-based transistors and neuromorphic applications.