Study the opto-structural properties of the mixed halide perovskite films by maintaining an equimolar stoichiometry of organic halide and metal halide composition in the precursor solution

Mixed halide perovskite films are important for various optoelectronic applications. This study involves the synthesis and characterization of mixed halide perovskite films MAPbBr_xI_3-x (where x = 0, 1, 2, 3), by maintaining a fixed 1:1 molar ratio of the methylammonium halide and lead halide in spin coating. The films were fabricated via the spin coating method on glass substrates. UV–visible absorption spectroscopy revealed a tunable optical bandgap ranging from 1.57 (MAPbI₃) to 2.27 eV (MAPbBr₃), corresponding to absorption edges that shifted from 788 to 547 nm as the bromine content increased. X-ray diffraction confirmed high crystallinity, particularly in MAPbBr₂I, which exhibited the most intense and sharp peaks. SEM analysis revealed varied morphologies influenced by the halide composition, with the fixed equimolar ratio resulting in well-defined and uniform crystal structures. Notably, MAPbBr₂I displayed a smooth and uniform surface, indicating superior film quality and minimized defect density. FTIR and Raman spectroscopy provided insights into molecular interactions, vibrational modes, and structural properties. This study uniquely highlights how maintaining a consistent organic-to-inorganic ratio influences the optical, structural, and morphological properties of mixed halide perovskites. The findings suggest that MAPbBr₂I, with its optimal crystallinity, bandgap, and morphology, is a promising candidate for optoelectronic applications.