DFT and TD-DFT studies of the effect of internal acceptor based on D-A’-Π-A structure for dye-sensitized solar cells

Economic growth and population expansion have led to an increase in the world’s energy consumption. For human use, solar energy is one of the greatest significant renewable energy sources. In this study, six D-A’-π-A of newly organic dye molecules (M1-M6) have been developed by changing the internal acceptor groups. Density functional theory (DFT) and time-dependent DFT (TD-DFT) theory techniques through B3LYP and 6-311G basis set have been employed to assess their optoelectronic properties as well as photovoltaic characteristics of six D-A’-π-A novel organic dyes designed molecules. A number of critical factors like geometrical optimization, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy level, energy bandgap and light-harvesting efficiency (LHE) have been studied so as to determine the effect of developed internal acceptor group on increasing intramolecular charge transfer (ICT) and improving light-absorbing capacities. From the data, out of all the developed six organic dye molecules, M2 perform better than other organic dye molecules, showing injection driving force (ΔGinject) of -0.1807 eV and -0.1125 eV for gas phase and solvent phase, respectively, open-circuit voltage (Voc) of 0.3003 eV and 0.2516 eV for gas phase and solvent phase, respectively, and maximum absorption wavelength of 959.76 nm and 1148.69 nm for gas phase and solvent phase, respectively. Therefore, M2 dye molecule was observed to be more favorable candidate in the application of dye-sensitized solar cells (DSSCs) technology hence recommended for practical study to offer effective advancement in D-A’-π-A system organic dye for sustainable energy development. Additionally, this study contributes to directing researchers for further study toward designing more effective novel organic dye molecules for DSSCs application.