Anion influence on electronic and optical properties of several iodobismuthates

Abstract

Complex lead iodide hybrid perovskites show high photovoltaic efficiency, but their use in solar cells may be limited due to Pb toxicity and its great bioavailability because of its solubility in water. Iodobismuthates can emerge as a promising alternative for solar cells, having no toxicity and exhibiting high stability in relation to the oxidation in air. To know if the iodoplumbates can be substituted with less toxic iodobismuthates without reducing the photovoltaic efficiency, microscopic contributions to the absorption coefficients are analyzed for two compounds. The absorption coefficients were obtained from first principles. To identify and quantify the most important contributions to the optical gaps, the absorption coefficients are split as an exact many-species expansion. From the results, the electronic and optical gaps are different. Additionally, the optical gap and the optical properties are rather insensitive to the cationic structure.