First-Principles Study on Optoelectronic and Photovoltaic Properties in a P3HT/PCBM Complex

Due to their diverse potentials, solar cells based on conjugated polymers have attracted attention over the past decades. In this study, ten poly(3-hexylthiophene) (P3HT) have been studied by performing computations based on density function theory and time-dependent density function theory with the increasing of molecular chains. The effect of the increasing of monomer numbers on the optoelectronic properties has been investigated, including molecular frontier orbitals (FMOs), molecular electrostatic potential (MEP), global reactivity descriptors, dipole moment, charge mobilities, and optical characteristics. The results demonstrate that M(n=3) has a smaller gap energy, best optical properties, and highest charge mobilities. We investigate the photovoltaic characteristics of novel donors using (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor. As a result, compounds M(n=1) to M(n=10) have an efficient electron transport from donor to acceptor. These outcomes suggest the possibility to test these engineered molecules in the laboratory, in order to improve organic solar cells (OSCs).