Three component superlattice enhanced stability for photovoltaic applications: a first principles study

Abstract

The use of superlattices is an attractive method to improve the stability and optoelectronic properties for enhanced photovoltaic performance. In this study, we construct ten superlattices composed of three unit cells of methylammonium tin halide perovskites MASnI₃, MASnBr₃, and MASnCl₃, a structure never considered before. First-principles density functional theory (DFT) calculations are perfomed on the new trilayer superlattice to explore the effects of stacking order on its structural, electronic, and optical properties. The results show that all studied materials exhibit improved thermodynamic stability and adjustable bandgaps, demonstrating the effectiveness of the superlattice structures. In particular, MASnI₃/MASnI₃/MASnI₃, MASnI₃/MASnBr₃/MASnI₃, and MASnI₃/MASnCl₃/MASnI₃ have small binding energies and bandgaps of 1.56, 1.58, and 1.46 eV respectively, which are suitable for high-efficiency photovoltaic materials. The absorption spectrum and photovoltaic parameters also reveal their high optical absorption (over 10⁵ cm⁻¹) in the entire visible light region and theoretical efficiences reaching over 20%, proving the potential of these three superlattices as novel nontoxic perovskite materials for photovoltaic and optoelectronic applications.