From Pb‐based MAPbI_3−xCl_x to Pb‐free FASnI_3−xCl_x and CsSbCl₄ derivatives fabrication in atmospheric conditions for optoelectronic and solar cell applications

Abstract

MAPbI3 is the most attractive perovskite, but toxicity and instability issues hinder its commercial applications. Stability can be improved by halide mixing; however, Pb‐free perovskites are designed to alleviate the toxicity and to enable green photovoltaics (PVs). To this end, MAPbI3‐xClx, FASnI3‐xClx and CsSbCl4 films are deposited by spay pyrolysis technique in atmospheric conditions. SEM images demonstrated that through this process, high quality film fabrication is possible. Color of the precursor solutions changes with stirring time. High crystallinity and existence of mixed‐phases are confirmed by XRD analysis. Compositions greatly impact the morphology and optical properties. Value of α is larger than 105 cm−1 for all films. Band gaps of FASnI3‐xClx and CsSbCl4 are 1.46 eV and 1.52 eV, which are more suitable for PVs, optoelectronic applications than MAPbI3‐xClx (Eg = 1.59 eV). The efficiency was obtained as 16.34%, 9.90%, and 13.08% for deposited MAPbI3‐xClx, FASnI3‐xClx, and CsSbCl4 films. The lower efficiency can further be enhanced by optimizing parameters, and in this study it was found as 20.78%, 11.93%, and 18.02%. Theoretical calculations show the films can easily produce O2 by a strong oxidation process. Thus, the favorable characteristics of FASnI3‐xClx and CsSbCl4 make alternative Pb‐free perovskites for PV, electronic, and optoelectronic applications.image