Characterization and Theoretical Insights Into Coumarin-Based Sensitizers for Dye-Sensitized Solar Cells

Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to evaluate the potential of coumarin-based dyes, 7-diethylamino-4-methylcoumarin (DAMC), Coumarin 102 (C102), Coumarin 153 (C153), Coumarin 343 (C343), Coumarin 6 (C6), Coumarin 7 (C7), and Coumarin 30 (C30), as sensitizers for dye-sensitized solar cells (DSSCs). Complementary experimental studies were performed to assess their photovoltaic performance. UV-vis absorption spectroscopy revealed the optical behavior of both isolated dyes and dye-sensitized TiO₂ films, highlighting variations in light-harvesting capabilities and adsorption strengths. C343 exhibited the most favorable photovoltaic response among the investigated dyes, enabling mechanistic correlations between molecular structure, light-harvesting, charge-transfer dynamics, and device performance. C343 displayed short-circuit current density (J_SC) of 1.12 mA cm^-2, an open-circuit voltage (V_OC) of 259 mV, and a fill factor (FF) of 40.