Exploring the Efficiency of C343 Coumarin Dye-Sensitized Solar Cells Using Substituents

Coumarin dyes are used in dye-sensitized solar cells due to their fluorescent nature and solar stability. However, coumarin dyes exhibit limited absorption of light in the visible region, making it essential to improve their performance in dye-sensitized water-splitting solar cells. The current study uses computational chemistry methods to investigate the light absorption capacity of a coumarin dye by altering the chromophoric system and applying an electric field. Eight novel dyes were considered from the reference coumarin C343 dye, and they were studied using DFT, TD-DFT, and a solar cell capacitance simulator. The absorption spectra of some of the substituted dyes show a redshift, indicating a decrease in the HOMO-LUMO gap, which is suitable for solar cell application. One of the derivatives was found to be most effective, with a band gap of 2.24 eV in the gas phase and 1.78 eV in water; a maximum absorption wavelength of 554 nm in the gas phase and 698 nm in water; a power conversion efficiency of 10.2% under standard AM 1.5 irradiation (100 mW cm^-2).