Investigation of (CsMA)NaBiX$_6$ (MA= methylammonium; X=Cl,Br, I) Organic-Inorganic Hybrid Double Perovskites for Optoelectronic Applications: A First Principles Study

Abstract: Organic-inorganic hybrid double perovskites have attracted increasing interest in the commercialization of lead-free and nontoxic perovskites due to their unique optoelectronic properties compared with inorganic perovskites. In this study, the structural, electronic, optical and properties of 3 Pb-free compounds (CsMA)NaBiX$_6$ (MA= methylammonium; X= Cl, Br, I) were simulated using first-principles density functional theory (DFT). Results show that the investigated compounds are semiconductors with tunable bandgaps characteristics that can be used in devices like light emitting diodes, and predict the suitability of the (CsMA)NaBiI$_6$ organic-inorganic hybrid double perovskite in this study for optoelectronic applications owing to its high absorption coefficient (in the order of $10^6$cm$^{-1}$), dielectric constant ($\approx 3.24$), and refractive index (2.50) as well as its stability as revealed by its high formation energy. Additionally, the high absorption coefficient, high refractive indices and dielectric constants of the investigated materials posits that they have a number of optoelectronic applications including photovoltaic cells among others.