Investigation of air-stable Cs₂SnI₆ films prepared by the modified two-step process for lead-free perovskite solar cells

In recent years, the organic-inorganic perovskite materials have revolutionized the Photovoltaic industry with highly efficient power conversion devices accompanied by a high growth rate. However, these devices experience major environmental and stability issues that hinder their true potential. More recently, a rarely studied perovskite material Cs₂SnI₆ is gaining enormous attention due to its superior stability and suitable bandgap. In this work, we developed a modified two-step process to prepare uniform Cs₂SnI₆ films, and the influence of the reaction conditions on the properties is explored. The structural, morphological, optical, and electrical properties of the prepared films were investigated using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-vis spectrometer, photoluminescence, and Hall Effect measurements, respectively. Phase stability and morphology of the films are improved with optimizing the reaction conditions. The results confirm the n-type semiconductor nature of Cs₂SnI₆ with bandgap ranging from 1.29 eV to 1.42 eV with maximum carrier mobility of 425 cm² V^-1 s^-1. The present study will further provide potential research directions in improving the device efficiency of air-stable Cs₂SnI₆ perovskite solar cells. Supplementary material for this article is available online.