Metal-Organic Chemical Vapor Deposition of Hybrid Perovskites

Hybrid perovskites (HPs) have become widely recognized in the chemistry and materials science communities as a promising candidate for the next generation of efficient optoelectronic and photovoltaic devices. Their unique hybrid organic-inorganic nature affords HPs an exciting blend of electronic and structural properties, and yields both advantages and challenges in fabrication. The vast majority of HP fabrication methods to date have focused on simple solution processing, while comparatively few vapor-phase HP deposition methods have been developed, and these broadly rely on single-source evaporation of solid HP perovskite crystals or dual-source coevaporation of precursor salts. However, these methods suffer from limited control over reactant vapor pressures and temperatures that in turn lead to limited control over final film composition and morphology. In light of this, we have developed a metal-organic chemical vapor deposition (MOCVD) method for HP fabrication to enable precise control of composition, stoichiometry, and film morphology. Using our custom-built reactor equipped with vapor precursors including methylamine, tetraethyllead, and hydrogen halide gasses, we have successfully deposited continuous thin films of phase-pure CH₃NH₃PbI₃ perovskites as confirmed using X-ray diffraction, UV-visible and photoluminescence spectroscopy, and scanning electron microscopy. We further probed deposition on a variety of substrates including FTO-glass, silicon oxide, and organic-functionalized materials to investigate the vital relationship between substrate identity and film nucleation and growth dynamics.