Exploring the optoelectronic properties of novel lead-free double halide perovskites Cs2NaInX6 (X=Br, Cl, I) for photovoltaic applications: DFT study

Materials science is crucially involved in researching advanced materials for energy conversion and storage. The discovery process has been accelerated by computational simulations, which have become a powerful tool for predicting the properties of new materials in recent years. This study examines the structural, electronic, and optical properties of double perovskites Cs2NaInX6 (X = Br, Cl, and I), emphasizing their potential use in energy conversion. Relevant results for optoelectronic applications have been obtained through a comparative study of the studied halide double perovskites. The compounds exhibit a high absorption coefficient of over 10(6) cm(-1) in the ultraviolet, as demonstrated by the obtained results. In addition, these compounds are able to absorb light with a maximum absorption of 10(5) cm(-1) in the visible range. Cs2NaInX6 double perovskite compounds exhibit direct semiconductor behavior with optical bandgap energy values of around 2.46, 3.44, and 1.64 eV for Cs2NaInBr6, Cs2NaInCl6, and Cs2NaInI6, respectively. The reached results led to the conclusion that Cs2NaInX6 compounds can be used as a promising candidate for optoelectronic and solar cell applications. Our understanding is that this is the first theoretical prediction of the electro-optical properties of these compounds that has not yet been confirmed experimentally.