Growth of Tin Halide Perovskite Film on Two-Dimensional Hexagonal Boron Nitride via Thermal Evaporation

Tin halide perovskites have served as channel materials for p-type transistors owing to their low hole effective mass and suitable hole density. However, they suffer from uncontrolled film crystallization, leading to excessive tin vacancies and self-p-doping. In this study, we report a facile way to grow three-dimensional (3D) tin halide perovskite films by thermal evaporation on a dangling-bond-free hexagonal boron nitride (hBN) surface. The hBN, transferred onto SiO₂ as a gate dielectric/channel interlayer, offers a hydrophobic surface that promotes the crystallization of CsSnI₃ films by reducing the nucleation site density, increasing the nuclei size, and promoting the formation of uniformly oriented enlarged grains. CsSnI₃ films grown on hBN exhibit reduced pinholes and grain boundaries, reducing the concentration of tin vacancies. Thin-film transistors using these films demonstrate accelerated charge transport with large current modulation without any additives. The proposed strategy can facilitate the engineering of defect-free perovskite channel layers for integrated perovskite electronics.