This work reports results of a study on optical, morphological and structural properties of thin films of cesium lead bromide iodide mixed perovskite synthesized by sequential evaporation of precursors. Thin films of CsPbBr₃₋ₓIₓ with a high degree of reproducibility of both the molar composition and the photovoltaic properties were achieved, using an electronic system with facilities to control the growth of the samples. Special emphasis was put in evaluating the effect that the substitution of the Pb cation by Zn²⁺ ions onto its optical, morphological and structural properties through transmittance, photoluminescence, XRD, SEM and Urbach Energy measurements.
Thin films of CsPbBr₃₋ₓIₓ were prepared by sequential evaporation of its precursors (PbBr₂, PbI₂, CsBr), using a routine that includes initial evaporation of PbI₂ followed by evaporation of PbBr₂ and CsBr, keeping their respective deposition rates in the range of 4–6 Å/s. The precursors are evaporated at room temperature from Knudsen cell-type evaporation sources and after the deposition, these are annealed at normal ambient air conditions at temperatures around 250 °C, for 20 minutes. Good reproducibility of both the composition and properties of samples was achieved using equipment with facilities to control electronically the evaporation temperature and deposition rate of precursors, by means of PID and PWM algorithms. After obtaining conditions to grow thin films with composition CsPbBr₂.₇I₀.₃, a study was carried out to evaluate the influence that the partial substitution of Pb by Zn²⁺ (obtained by additional evaporation of a layer of ZnBr₂) produces on the optical, morphological and structural properties.