Triselenasumanene-based organic molecules as donor and hole-transporting materials for next-generation solar cells

Abstract

The optoelectronic and charge transport properties of triselenasumanene-based organic molecules were studied using electronic structure calculations to explore their potential as a hole-transporting material (HTM) in perovskite solar cells (PSCs) and as electron donors in organic solar cells (OSCs). Based on the recently synthesized triselenasumanene (SESUM) molecule, nine molecules (SESUMXn, where X = anthracene (A), tetracene (T) and pentacene (P), n = number of attached A, T and P, i.e. 1, 2 and 3) were designed by extending the π-conjugation. The newly designed molecules possessed suitable energy-level alignment with the energy bands of commonly used perovskite material, CH3NH3PbI3, in PSCs, and are suitable as electron-donor material with the commonly used acceptor material, PC61BM, in OSCs. The calculated ionic state properties and electrophilicity index also showed that the studied molecules were potential donor materials for OSCs. Further, the calculated open circuit voltage and fill factor of SESUM and anthracene- and tetracene-substituted SESUM molecules were comparable with those of recently reported donor molecules. The calculated absorption spectra, effective hole transfer integral and stacking angle distribution showed the suitability of SESUMX2 and SESUMX3 molecules as HTM in PSCs. The results of periodic density functional theory calculations showed that the tri-substituted SESUM molecules, SESUMX3 (where, X = A, T and P), were effectively adsorbed on the CH3NH3PbI3 surface and abstracted the hole carrier from the perovskite surface.