Investigation of the impact of internal acceptor and π-linker in 2, 5-di(2-thienyl)pyrrole based organic dye photosensitizer for DSSCs

The effect of π-linkers and internal acceptor group on the optoelectronic characteristics of D-π-A and D-A′-π-A dyes for dye-sensitized solar cells (DSSCs) were examined. The DFT was used for estimating geometries and charge transport parameters, and the TD-DFT for calculating electronic excitations of these dyes. HOMO, LUMO, and HOMO-LUMO energy gap were also calculated for appreciating the suitable electron transfer, dye regeneration, and charge injection. For achieving the improved performance of dyes in DSSC, injection driving force (ΔG_inj), short circuit current density (J_SC), the open circuit voltage (V_OC), light harvesting efficiency (LHE), dye regeneration energy (ΔG_reg), and Power conversion efficiency were also determined. For suitable Power conversion efficiency of the DSSCs, electron affinity (EA), hole and electron extraction potential, Ionization potential (IP), Total density of states, and Electrostatic potential (ESP) were also calculated. The result shows that the internal acceptor and π-linkers affect the photovoltaic parameters and a small variations in the dye architecture increase the efficiency of DSSCs. The dyes containing biphenyl π-linkers showed maximum power conversion efficiency for solar cell.