In this project, the purpose of computational studies is to attain deeper insight into the fundamental physicochemical processes that occur in the molecular solar cells – i.e., dye-sensitized solar cells (DSSCs) – so that rational development of better DSSCs would become more feasible. The dye-sensitized solar cell (DSSC) [O’Regan, B.; Grätzel, M., Nature, 1991, 353,737; Bach, U.; Grätzel, M., et al., Nature, 1998, 395, 583.] is one of remarkably fruitful and promising molecular approaches in its own right and it is also a platform from which a number of promising hybrid (integrated) devices have emerged recently [Yun, S.; Qin, Y.; Uhl, A. R.; Vlachopoulos, N.; Yin, M.; Li, D.; Han, X.; Hagfeldt, A. Energy Environ. Sci. 2018, 11, 476-526.]; and, perovskite solar cells (PSCs) have also emerged from DSSC field. With regard to DSSCs as part of nowadays merged research field of “molecular photovoltaics”, one of really urgent needs is the better understanding of critically important interactions and processes at the time-resolved molecular level. Therefore, the overall goals for us are to investigate surface-dye, dye-dye and dye-electrolyte interactions which govern the organization of structurally complex dyes on a surface and the redox chemistry. With that, use of the cutting-edge computational methods will contribute towards better molecular-level rationalization of the macroscopic-level data from experiments utilizing spectroscopy. We plan to focus our research on recently developed ruthenium-free dyes with state-of-the-art performance plus the iodide-free redox mediators with promisingly high performance as well. More specifically, we plan to use the ab initio and other formulations of molecular dynamics (MD) in order to elucidate and better understand dye-organization on mesoporous surface (TiO2), interactions between the oxidized/reduced dye and the redox mediators with explicit (realistic) account of actual electrolyte’s constituents, characteristics of dye-aggregate(s) at finite temperature and the coupling between nuclear motion (vibrations and structural fluctuations) and the hole-transport at finite temperature.