DESIGNING INDIGO-BASED HTMS FOR SN-PEROVSKITE PHOTOVOLTAICS: A COMPUTATIONAL APPROACH

Abstract

Indigo-based structures were designed with the help of density-functional theory (DFT) and proposed as potential hole-transporting materials (HTMs) for tin-based and mixed-metal perovskite solar cells (PSCs). First, theoretical methodology was benchmarked to determine the most appropriate functionals for optimization and calculation of the energies of indigo-based structures, using reference structures with known energies. A linear mathematical model was built based on calculations of reference structures, to estimate and predict actual energy levels of indigo-based molecules. It was shown that GSOPv is a good estimation of actual HOMO energy for indigoid structures. Next, the influence of position of attachment of new substituents on the final HOMO energy was studied and used for design of new structures. Indigoids with alkoxy and alkylamine groups attached at 5,5’- positions, as well as asymmetric structure with cyclic and alkylamine groups attached, were demonstrated to have suitable energetics for application as HTMs for CsSnI3 and MASn0.5Pb0.5I3 PSCs.