Enhancing organic SCs efficiency with CSi quantum dots in A–π–D architectures

Abstract

This study explores the optoelectronic and photovoltaic potential of acceptor–π–donor (A–π–D) architectures utilizing CSi quantum dots (CSiQDs) through a combination of density functional theory (DFT) and time-dependent DFT (TDDFT). We examined two key structural configurations: C–C and Si–C conformers. In these systems, CSiQDs serve as the acceptor, C₄H₃SF as the π-bridge, and 3 × (C₄H₄O) as the donor. Despite slight structural distortions in the C–C conformer, all configurations demonstrated reliable energetic stability, indicating their robustness. A notable finding of this study is the effect of solvents on the HOMO–LUMO (H–L) energy gap. Our results show that solvents increase the H–L gap for C–C conformers while reducing it for Si–C conformers, highlighting the flexibility of Si–C bonds compared to the rigidity of C–C bonds. This structural adaptability of Si–C conformers opens new possibilities for tuning optoelectronic properties in response to environmental conditions. Optical analysis revealed a substantial red shift in the absorption spectra in the presence of a solvent, which enhances light absorption in the visible range—a crucial aspect for photovoltaic efficiency. Furthermore, the C–C conformers exhibited strong open-circuit voltage (V_oc), while lower exciton binding energies in both conformers indicate potential for improved charge separation and transport. The ability to tailor optoelectronic properties through solvent interactions and the demonstrated stability of these configurations position them as strong candidates for next-generation energy harvesting technologies.