Potassium tin mixed iodide-bromide KSn(I1-xBrx)3 [x = 0.25,0.5,0.75,1] perovskites for solar cell absorbers: A computational study

Abstract

Metal-halide perovskite (PVK) materials have been the subject of investigation in the photovoltaic community because of their remarkable optoelectronic characteristics. Nonetheless, the extrinsic and intrinsic instabilities of PVK materials remain a major obstacle to their commercial fabrication prospects. This problem can be resolved through halide mixing. In the current study, we examine the elastic, structural, mechanical, thermal, electronic, optical, and thermoelectric properties of potassium tin mixed iodide-bromide(I-Br) PVK, KSn(I1-xBrx)3 [x = 0.25, 0.5, 0.75, 1] (KSnIBr). With an increase in bromine concentration, KSnIBr’s thermodynamic stability is found to rise. The elastic properties demonstrate the mechanical stability of the PVK materials. The Pugh’s ratio, Cauchy’s pressure, and Poisson’s ratio highlight their ductility. Ductile materials are desirable for the formation of thin films. An extremely high melting point ensures that the PVK materials retain their solid state even at very high temperatures. The high absorption coefficient (αω), low energy loss factor (L(ω)), and low reflectivity(R(ω)) in the visible region are used to pitch their candidature as absorber materials in perovskite solar cells (PSC). A bandgap (Eg) of 1.9 eV, 1.9608 eV, 1.9761 eV, and 2.1285 eV is obtained for KSn(I0.75Br0.25)3, KSn(I0.5Br0.5)3, KSn(I0.25Br0.75)3, and KSnBr3 respectively. A single junction perovskite solar cell utilizing the KSnIBr perovskite is simulated using SCAPS software. An efficiency of 11.31 %, 10.3 %, 9.89 %, and 8.05 % are reported for KSn(I0.75Br0.25)3, KSn(I0.5Br0.5)3, KSn(I0.25Br0.75)3 and KSnBr3 PVK respectively. These wide bandgap perovskite materials in conjunction with other narrow bandgap materials may be beneficial for the design of tandem solar cells in future.