Mixed halide head perovskites thin films: Stability and growth investigation

Herein, we investigate the mixed halide perovskite films with the formula MAPbX(3) where (X-3 = Br-3, Cl-3, I-3, Br2Cl, Br2I, and I2Cl) prepared by Spin-Coating in order to study the effects of partial and total substitution of Br. For this purpose, we have carried out a series of characterization techniques, including x-ray diffraction (XRD), Scanning electron microscopy (SEM), UV-visible spectroscopic; we find that all films content with partial Bromide exhibit two peaks located at 2 theta angles of 14,94 and 30,2 matching to crystallographic planes (110) and (220) respectively correspond to perovskite structure, in the case of MAPbCl(3), MAPbI(3) or mixed MAPbI(2)Cl the characteristics peaks (110) and (220) were identified at 2 theta angles of 14,16 degrees and 28,53 degrees respectively. The surface morphology of the different mixed lead halides films was examined by SEM, MAPbBr(2)I has the highest crystallinity and grain size. Furthermore, All the mixed halide films exhibited strong absorbance with bandgap values ranging between 1.5 eV and 2.5 eV. Moreover, we investigated the crystal structure, morphology, and color change of MAPbX(3) after four weeks under dark with 22% humidity; the Bromide-doped samples demonstrate a higher degree of stability based on the study of their degradation mechanisms.