Effect of the precursor's stoichiometry on the optoelectronic properties of methylammonium lead bromide perovskites

Methylammonium lead bromide (MAPbBr₃) perovskites have been widely studied in applications such as lasers and light-emitting diodes, thanks to their favorable bandgap, efficient charge transport, and the possibility of processing by simple solution methods. The film morphology has a large impact on the optical and electronic properties of the material; hence the deposition methods and the type of precursors used are crucial in the preparation of efficient optoelectronic devices. Here we studied the effect of the precursor´s stoichiometry of solution processed MAPbBr₃ thin films on their optical and electronic properties. We found a drastic effect of the stoichiometry on the resulting thin film morphology, and suggest the use of excess MA cations to enhance the photo- and electroluminescence of hybrid perovskites.