Optimized Substrate Orientations for Highly Uniform Metal Halide Perovskite Film Deposition.

Uniform optoelectronic quality of metal halide perovskite (MHP) films is critical for scalable production in large-area applications, such as photovoltaics and displays. While vapor-based MHP film deposition is advantageous for this purpose, achieving film uniformity can be challenging due to uneven temperature distribution and precursor concentration over the substrate. Here, we propose optimized substrate orientations for the vapor-based fabrication of homogeneous MAPbI thin films, involving a PbI primary layer deposition and subsequent conversion using vaporized methylammonium iodide (MAI). Leveraging computational fluid dynamics (CFD) simulations, we confirm that vertical positioning during the PbI layer growth yields a uniform film with a narrow temperature distribution and minimal boundary layer thickness. However, during the subsequent conversion step, horizontal substrate positioning results in spatially more uniform MAPbI thickness and grain size compared to the vertical placement due to enhanced MAI intercalation. From this optimized substrate positioning, we observe substantial optical homogeneity across the substrate on a centimeter scale, along with uniform and enhanced optoelectronic device performance within photodetector arrays. Our results offer a potential path toward the scalable production of highly uniform perovskite films.