Advancing organic solar cells: The role of CSi quantum dots in optimized donor–acceptor configurations

Abstract

In this study, we performed Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) calculations in order to explore the optoelectronic and photovoltaic properties of donor–acceptor (DA) architectures for organic solar cells (OSCs). The study focused on employing donor molecules comprising oligofuran and oligothiophene, paired with CSi quantum dots as the acceptor nanomaterial. Analysed in both gas phase and chlorobenzene solution, three DA categories were identified: coplanar, nearly coplanar, and twisted nanomaterials. The results demonstrate that these structures are energetically stable, with Si-C conformers exhibiting superior stability and greater electrophilicity compared to C-C conformers. Conjugation within these structures reduces the HOMO–LUMO gap due to significant hybridization of frontier molecular orbitals and slightly decreases the optical energy gap. The high absorption peak intensities and suitable optical energy gap values in chlorobenzene make these materials promising for photovoltaic applications. Calculations of the open-circuit voltage further confirm that these DA structures are excellent candidates for enhancing OSCs performance.