Hole transport materials for perovskite solar cells: A computational study

Abstract

Small molecule semiconductors are gaining lot of attention because of their reproducible electrical and optical properties in device as compared to batch to batch variation of macromolecules and polymers. Detailed information about the molecular levels of the molecules can be attained by systematically performing theoretical calculation followed by comparison with experimental values. For the theoretical studies hybrid density functional B3LYP level of theory is a very good method for predicting the reliable geometry, electronic structure and properties of conjugated systems. In the present work, we have considered a series of well-known and efficient small molecules used as hole transport materials in perovskite solar cells. We have calculated the band gap, HOMO, LUMO and geometry of these molecules based on triphenylamine, thiophene, triazatruxene, carbazole, triazine and tetraphenyl-benzidine unit using the hybrid density functional (B3LYP/6-31 g(d) and B3LYP/6-311 g) level of theory and correlated with experimental values. The study provides details about the effect of moieties used for designing the molecules, extended conjugation, substitution on charge density distribution, HOMO, LUMO and band gap of the small molecules.