Structure modification to tune the electronic and charge transport properties of solar cell materials: Quantum chemical study

Abstract

The ground states geometries of naphtho[2,3-b]thiophene derivatives have been optimized by using density functional theory (DFT) at B3LYP/6-31G** level of theory. The excitation energies have been computed by using time dependent DFT. The investigated dyes have been investigated with respect to dye-sensitized solar cells (DSSCs) and hetero-junction hybrid solar cells. The electron injection (ΔG r inject), electron coupling constants (|V RP |) and light harvesting efficiencies (LHE) of studied compounds have been discussed with esteem to DSSCs. The ΔG r inject and |V RP | of new designed derivatives showed that these materials would be efficient DSSC materials. The electron affinities, reorganization energies, diagonal band gaps, and energy level offsets have been studied to shed light on the electron transfer behavior of studied materials with respect to hetero-junction hybrid solar cells. The higher electron affinities of 2, 4 and 6 revealed that the electron transport toward cathode in hetero-junction solar cells would be superior ultimately improve the open circuit photovoltage (V oc). The higher diagonal band gap for 2, 4 and 6 compared to their counterparts (1, 3 and 5) showed that these dyes might have higher short-circuit current density (J sc) and fill factor (FF). The hole and electron reorganization energies showed that these materials would be efficient charge transporters.