Ns2-containing vacancy-ordered double perovskites for optoelectronic applications: A first-principles investigation

Abstract

Vacancy-ordered double perovskites have attracted broad attention due to the thermostability and excellent optoelectronic properties. Here, we report first-principles investigations on optoelectronic properties of a series of ns2-containing vacancy-ordered double perovskites by substituting monovalent Cs with divalent Ba. These perovskites are predicted to show indirect bandgaps similar to the bismuth-based double perovskites. Unlike the regular metal halide perovskites, the 6s orbital of A-site Ba cation in these ns2-containing compounds composes lower conduction bands, and calculated dipole matrix elements demonstrate the influence of A-site Ba 6s-orbital on the optical absorption. Moreover, decomposition energies, electronic bandgaps, and effective masses of holes and electrons are calculated to assess the potential optoelectronic application, which could be a theoretical guide for exploring novel lead-free perovskite materials.