Abstract

This work reports the results of a study on the optical, morphological, and structural properties of cesium lead bromide iodide mixed perovskite thin films (CsPbBr3−xIx), synthesized by sequential evaporation of precursors (CsBr, PbBr2, PbI2). First, the deposition conditions were optimized to obtain thin films predominantly composed of the pure CsPbBr3 phase. Subsequently, the influence of partial substitution of Br− by I− on the film properties was investigated. Particular emphasis was placed on evaluating the effect of partial Pb2+ substitution by Zn2+ on the optical, morphological, electronic, and structural properties using optical transmittance, photoluminescence, scanning electron microscopy (SEM), X-ray diffraction (XRD), Urbach energy analysis, and density functional theory (DFT) calculations. Zn2+-doped CsPbBr3−xIx films were prepared by evaporating a ZnBr2 layer onto the pre-deposited PbBr2/PbI2 precursor layers. It was found that Zn2+-doped inorganic CsPbBr3−xIx perovskite films exhibit enhanced crystallinity and improved surface morphology. Additionally, photoluminescence characterization confirms that non-radiative recombination decreases significantly, apparently due to a reduction in intrinsic defect density. The effect of Zn2+ doping on the power conversion efficiency of carbon-based planar solar cells was also evaluated. Collectively, Urbach energy, photoluminescence, and SEM analyses revealed that the optimal Zn2+ doping range for CsPbBr3−xIx perovskite films is ≤5%.

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