Solvent-free and large area compatible deposition of methylammonium lead bromide perovskite by close space sublimation and its application in PIN diodes

Abstract

In this work, a solvent-free method to deposit in-situ methylammonium lead bromide (MAPbBr3) perovskite thin films is discussed. Spin-coating methods used for hybrid perovskite deposition typically use solvents that might remain in the films after processing, potentially causing accelerated film degradation. Furthermore, spin-coating might not be suitable for applications that require thick films (>500 nm). To address these issues, a close space sublimation process was implemented to deposit solvent-free and in-situ MAPbBr3 films with variable thicknesses. A post-deposition annealing protocol was developed that results in smooth perovskite films as thick as 3 μm. Post-deposition anneal also reduces a photoluminescence emission band that originates from surface defects. The resulting films were chemically, optically and structurally studied and hysteresis-free PIN diodes with metal-oxide semiconductors as p and n-type layers were fabricated and analyzed. The results indicate that high quality perovskite films with variable thickness can be obtained by the close space sublimation (CSS) process demonstrated here. Although MAPbBr3 was selected for this study, this CSS method demonstrated can be easily applied to other hybrid perovskites.