Optical and structural investigation of methylammonium lead perovskite mixed halide (I, Br, and Cl) on spin-coated zinc oxide

Abstract

This study investigated the effect of mixing different halides bromine (Br) with iodine (I) and Br with chlorine (Cl) and using only bromide for methylammonium lead perovskites films deposited in ZnO to produce different heterojunctions ZnO/MAPbBr3, ZnO/MAPbBr2I and ZnO/MAPbBr2Cl. Thus, these three heterojunction samples were produced and characterized. The perovskite is deposited at ZnO films showed two main peaks located at 2θ = 33.66° and 2θ = 37.69°. These peaks correspond to the (002) and (101) planes of the hexagonal wurtzite structure of ZnO respectively. The XRD results indicate that all the heterojunction samples show two main peaks at 2θ = 14.79° and 2θ = 29.83° for the (100) and (200) crystallographic planes respectively. The peaks of the sample mixed with iodine are the most intense and those of the sample mixed with chlorine are the least intense. These results also reveal that the mixed samples have lower crystallinity than the unmixed ZnO/MAPbBr3 sample. The SEM results confirmed this. The UV–Visible results indicate that the sample mixed with iodine absorbs the most and has the smallest band gap of 2.15 eV. The band gaps of the heterojunctions range from 2.15 eV to 2.4 eV. The unmixed sample (ZnO/MAPbBr3) has the largest band gap. The degradation study showed that the sample mixed with iodine degrades faster.

Keywords

• Perovskite
• Mixing
• ZnO
• Heterojunction
• Thin film
• Stability