Effect of CH3NH3I/CH3NH3Br precursors on the structural and surface morphology properties of the electrodeposited methylammonium lead–mixed halide perovskite films

Abstract

Organometallic halide perovskites have been arisen as a class of multi-purpose materials with exciting applications in optoelectronic devices such as solar cells, light-emitting diodes, photo detectors, and laser diodes. In spite of a significant hope in performance, still production process in ambient air and its stability must be addressed as the main issues for this type of material. In this work, a versatile and scalable fabricating process of halide mixed perovskite layers through electrochemical deposition of PbO2 on FTO (fluorine-doped tin dioxide–coated glass) substrates and double-vapor transformation with HX and CH3NH3X (X = I & Br) vapors without using a glove box or a high vacuum system is demonstrated. Highly crystalline hollow-free electrodeposited perovskite layers on FTO substrate were achieved. Treatments with CH3NH3Br/CH3NH3I precursors were also investigated to check the possible impact on the quality of the final perovskite layer. It was illustrated that the use of CH3NH3I or CH3NH3Br precursors in the last step of the electrochemical synthesis can determine the properties of the perovskite film. When PbI2 and PbBr2 films exposed to CH3NH3Br vapor, bromine-treated perovskites were achieved with uniform grain size of ~ 1.5 to 2.3 μm. Similar treatment with CH3NH3I vapor led to the smaller grain size perovskite layers (~ 0.7 μm). Final properties of all fabricated layers, including optical absorption, bandgaps the crystalline phases, and chemical composition, were characterized and compared.