Thermally Evaporated High-Performance Metal Halide Perovskite Transistors

Advances in metal halide perovskites for optoelectronic devices have resurrected the their potential as channel layer for transistors. Over the past several years, notable performances have been reported for solution-processed metal halide perovskite transistors through fine-tuning of material composition, crystallization and device structure.^1-3 However, their ionic nature allows the channel layer to be susceptible to common solvents used in lithography, which is challenging for complex circuit integration, large-area or micro-scale electronics. Here, we present thermally evaporated metal halide perovskite, caesium-tin-iodide, as a channel layer for high-performance p-channel thin-film transistor. While thermal evaporation is a mature fabrication technique, the low crystallinity of deposited thin-films, when compared with those from solution-process, was a fundamental bottleneck. The chemical reaction can take place by overcoming high energy barrier for diffusion and solid-solid interaction, unlike fast ionic reactions of the solution-process.^4,5 By incorporating chloride-based additives that accelerate the solid-state diffusion under high thermal energy and alkali metal iodide additives that modulate the formation of nucleation sites, we achieved a highly crystalline film and high-performance thin-film transistor with field-effect hole mobilities over 30 cm²V^-1s^-1 and on/off current ratios exceeding 10¹⁰. High reproducibility and operational stability were attained in large-area wafer-scale to micro-scale devices, accentuating the highly promising and industry-ready thermally evaporated metal halide perovskite thin-film transistors.<br/><br/>1. H. Zhu et al. <i>Nat. Electron.</i> 6, 650-657 (2023).<br/>2. A. Liu et al. <i>Nat. Electron.</i> 5, 78-83 (2022).<br/>3. A. Liu et al. <i>Nat. Electron.</i> 6, 559-571 (2023).<br/>4. D. Lin et al. <i>Mater. Today Adv.</i> 16, 100277 (2022).<br/>5. Y. Vaynzof. <i>Adv. Energy Mater.</i> 10, 48. 2003073 (2020).