DFT and TD-DFT studies for optoelectronic properties of coumarin based donor-π-acceptor (D-π-A) dyes: applications in dye-sensitized solar cells (DSSCS)

Said A H Vuai; Mwanahadia Salum Khalfan; Numbury Surendra Babu

doi:10.1016/j.heliyon.2021.e08339

DFT and TD-DFT studies for optoelectronic properties of coumarin based donor-π-acceptor (D-π-A) dyes: applications in dye-sensitized solar cells (DSSCS)

Heliyon. 2021 Nov 9;7(11):e08339. doi: 10.1016/j.heliyon.2021.e08339. eCollection 2021 Nov.

Authors

Said A H Vuai¹, Mwanahadia Salum Khalfan¹, Numbury Surendra Babu¹

Affiliation

¹ Computational Quantum Chemistry Lab, Department of Chemistry, College of Natural and Mathematical Sciences, The University of Dodoma, Post Box: 338, Dodoma, Tanzania.

Abstract

A series of six coumarin based dye derivatives were investigated and their geometry and optoelectronic properties elucidated for suitability in dye-sensitized solar cells (DSSCs) using TD-DFT/B3LYP with 6-31G basis set. D-π-A schemes were developed by attaching various donors and acceptors to coumarin dye (CM) to calculate changes in their photovoltaic properties. D2-CM-A2 and D4-CM-A4 showed less dihedral angle because of the low steric effect between donor and connector. The D1-CM-A1 and D2-CM-A2 results of intramolecular charge transfer were higher because of low bond length and a strong group of electron donors. The results revealed that LUMO energies of D1-CM-A1, D2-CM-A2, D3-CM-A3 and D4-CM-A4 were higher than the conduction band edge of TiO₂ electrode (-4.0 eV) suggesting that these dyes will inject the electrons into the conduction band of the semiconductor. In addition, the light harvest efficiency (LHE), open-circuit voltage (V_OC) and band energy gap (E_g) values are calculated in the gas phase, as well as in the solvent phase. This study shows that D1-CM-D1 and D2-CM-A2 derivatives have better properties for application in the DSSCs.

Keywords: Acceptor; Coumarin dye; DFT method and photovoltaic properties; DSSCs; Donor.