Effect of tin concentration on the morphological & crystal structure, and optical properties of chemical vapor deposited MAPb1−xSnxI3 perovskite films for 0 ≤ x < 0.5

In this article, we evaluate the impact of Sn proportion on the morphology and crystal structure, and its influence on the optical properties of MAPb1−xSnxI3 (0 ≤ x < 0.5) perovskite films. The uniform and compact Sn-Pb halide films with a variety of grain sizes were deposited using a low-pressure chemical vapor deposition (LP-CVD) system and were sequentially converted into perovskite films. Rutherford backscattering spectrometry (RBS) measurements were performed to determine the depth profile of elements and the simulated spectra suggested multilayered films. The x-ray diffraction (XRD) patterns confirmed the formation of the perovskite phase, i.e. tetragonal structure with I4cm space group. The energy bandgap (Eg) and the Urbach energy (Eu) approximation insinuate a tradeoff between the attainment of low bandgap Sn-Pb halide perovskites and defect-disorder tolerant films.