Perovskite Pattern Formation by Chemical Vapor Deposition Using Photolithographically Defined Templates

Abstract

Thin film fabrication is necessary to realize the device integration of organic&#8211

inorganic hybrid perovskites (OIHPs), and solution-based crystallization methods have been employed widely to this end. Despite the versatility of the solution approach, device fabrication using typical “top-down” lithography is generally incompatible with as-prepared OIHPs films because of the low stability of perovskites to polar solvents involved in the lithographic process. Moreover, solution-prepared perovskites usually exhibit irregular surface roughness, implying the existence of randomly oriented crystal domains with a large density of grain boundaries, which are ultimately detrimental to the material properties. Here, we report a patterning of CH3NH3PbI3 (MAPbI3) thin films using a photolithographically fabricated cross-linked copolymer template on Si or SiO2 substrates via a chemical vapor deposition (CVD) method. Perovskite patterning is accomplished by growing PbI2 precursor layers selectively on template patterns and subsequently converting to MAPbI3 using CH3NH3I (MAI) in the vapor phase. We confirm that [0001]-oriented PbI2 nanoplatelets nucleate primarily on a Si or SiO2 surface and grow by surface diffusion from a polymer surface. The MAPbI3 conversion process preserves the original pattern morphology through the vapor&#8211

solid intercalation of MAI. Prototype photodetector arrays based on MAPbI3 patterns are also demonstrated. Our results highlight the advantages of the CVD patterning of perovskite materials in large-scale production for a range of optoelectronic applications.