Role of the chemical substitution on the structural and luminescence properties of the mixed halide perovskite thin MAPbI3-xBrx (0:1) films

Abstract

Mixed bromide iodide lead perovskites were prepared from methylamine, lead nitrate and the corre- sponding hydroX acid (X = I, Br), they were then deposited as thin films on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m in the composition range of 0.6-1. Mixed lead perovskites showed a high absorbance in the UV vis range. The band gap energy of thin films were estimated from absorbance spectral measurements, it was found that the onset of the absorption edge for MAPbI3- x Brx (x < 1) thin films is ranging between 1.58 to 1.72 eV. Photoluminescence emission energies for mixed halide perovskites presented intermediate values from 781 nm (MAPbI3 ) to 545 nm (MAPbBr3 ).