Effect of doping of NaI monovalent cation halide on the structural, morphological, optical and optoelectronic properties of MAPbI3 perovskite

Perovskite materials offer a compelling combination of low-cost and extraordinary optical and electronic properties. The optoelectronic properties of the CH3NH3PbI3 perovskite can be further improved by doping other ions. Here, we prepared the perovskite films in one-step method from a precursor solution containing a mixture of MAI, PbI2, and NaI (where MA stands for methylammonium cations) for a PbI2/MAI molar ratio of 1.08 to investigate influence of NaI-doping in perovskite on the structural and optoelectronic properties of CH3NH3PbI3 perovskite. Measurements based on UV–visible absorption spectrum and photoluminescence, reveal slight blue shift compared to pure MAPbI3. This experiment demonstrated that the pure MAPbI3 films were shown to be n-type and the electronic conductivity of MAPbI3 can be changed from n-type to p-type by doping Na+ cation. The hole concentration and Hall mobility of the NaI based perovskites exhibit an increase of up to an order of magnitude in the hole concentration with a significant decrease in the mobility compared to the pristine perovskite. These results indicate possibility of modulating semiconductor properties of CH3NH3PbI3 perovskite.