Comparative Investigation of MAPbBr$_x$I$_{1-x}$ and SbH$_4$Br$_x$I$_{1-x}$ Perovskites: Electronic and Structural Properties

Abstract: This paper comparatively investigates the structural and electronic properties of hybrid perovskites MAPbBr$x$I${1-x}$ and SbH$4$PbBr$_x$I${1-x}$ by means of DFT-based calculations. The main aim is to check if the increase in band gap due to substitution of I$^-$ ions with Br$^-$ ions can be overcome by introducing the inorganic SbH$_4^+$ cation. Since the Br$^-$ ions merely enhance structural stability of the perovskite framework and SbH$_4^+$ not only sustains that stability but also reduces the band gap to nearly ideal values and thereby improves electronic performance, these are the leading candidates among them. Of them, the reduced band gap SbH$_4$PbI$_3$ ($\sim$1.37 eV) and the perfectly matched SbH$_4$PbBrI$_2$ with its band gap being exactly 1.51 eV are top prospects for being stable and having high-efficiency solar cell applications. The findings show that SbH$_4^+$-based perovskites have potential for future photovoltaic devices.