Exploring the Efficiency\nof C343 Coumarin Dye-Sensitized\nSolar Cells Using Substituents

Coumarin\ndyes are used in dye-sensitized solar cells due to their\nfluorescent nature and solar stability. However, coumarin dyes exhibit\nlimited absorption of light in the visible region, making it essential\nto improve their performance in dye-sensitized water-splitting solar\ncells. The current study uses computational chemistry methods to investigate\nthe light absorption capacity of a coumarin dye by altering the chromophoric\nsystem and applying an electric field. Eight novel dyes were considered\nfrom the reference coumarin C343 dye, and they were studied using\nDFT, TD-DFT, and a solar cell capacitance simulator. The absorption\nspectra of some of the substituted dyes show a redshift, indicating\na decrease in the HOMO–LUMO gap, which is suitable for solar\ncell application. One of the derivatives was found to be most effective,\nwith a band gap of 2.24 eV in the gas phase and 1.78 eV in water;\na maximum absorption wavelength of 554 nm in the gas phase and 698\nnm in water; a power conversion efficiency of 10.2% under standard\nAM 1.5 irradiation (100 mW cm<sup>–2</sup>).