Metal Organic Chemical Vapor Deposition of Hybrid Perovskites.

Semiconductor devices often rely on high-purity materials and interfaces achieved through vapor- and vacuum-based fabrication methods, which can enable precise compositional control down to single atomic layers. Compared to groups IV and III-V semiconductors, hybrid perovskites (HPs) are an emergent class of semiconductor materials with remarkable solution processability and compositional variability that have facilitated rapid experimentation to achieve new properties and progress toward efficient devices, particularly for solar cells. Surprisingly, vapor deposition techniques for HPs are substantially less developed, despite the complementary benefits that have secured vapor methods as workhorse tools for semiconductor fabrication. For instance, metal organic chemical vapor deposition (MOCVD) emerged in the late 1960s as a vital tool to enable production of compound semiconductor and heterojunction devices, giving rise to tremendously important technologies such as solid-state lighting and diode lasers, yet there is no analogous MOCVD process for HPs. Here, using a custom-built two-zone reactor, we report the first MOCVD process for the direct vapor deposition of thick and continuous films of methylammonium lead halide (MAPbX; X = Br, I) from distinct organolead, halide, and amine vapor sources. Mechanistic investigation via kinetic studies and density functional theory (DFT) calculations suggest a multistep reaction mechanism that should be generalizable to a broad set of HP materials. We anticipate that the continued development of generic HP MOCVD processes will unlock compositional, crystallographic, and morphological control complementary to solution methods, enabling the rational design of material properties and pursuit of new applications.