Ground state geometries, UV/vis absorption spectra and charge transfer properties of triphenylamine-thiophenes based dyes for DSSCs: A TD-DFT benchmark study

DFT and TD-DFT calculations using ten various functionals contain 0 to 100% of HF exchange amount (BLYP, B3LYP, PBE0, M06, BHandH, BHandHLYP, M06-2X, CAM-B3LYP, LC-omega PBE and M06HF), in combination with ten double-zeta and triple-zeta basis sets of Poples, have been performed in order to explore their effects on the geometrical and electronic properties, and evaluate their accuracies to predict the visible spectra of C213, C214 and C215 triphenylamine-based (TPA) dyes for Dye-sensitized solar cells (DSSCs) applications. The calculation of the bond lengths and dihedral angle values for C213 dye ground state geometry showed a sensitive dependence to the percentage of HF exchange amount contribution in xc-functional, while the contributions of augmentation of the basis sets size has no remarkable effect from the 6-31G(d) basis set. Regarding the energies of the HOMO and LUMO levels, their calculation values were dependent on functional nature. The great accuracy to predict the ground state maximum absorption wavelength was showed by the functional approaches having HF exchange amount around 50%. The best prediction was recorded by BHandH functional using 6-31+G(d) basis set for both geometry optimization and TDDFT calculations within CPCM/THF solvent model. Using the lowest computational cost and accurate method, the light harvesting efficiency (LHE) was enhanced from C213 to C215 dye. Additionally, the injection driving force (Delta G(inject.)) to TiO2 semiconductor and the driving force for regeneration (Delta G(reg)) by I-/I-3(-) electrolyte were evaluated and suggest that the intermolecular charge-transfer mechanism is operative in the studied dyes when applied to DSSC. (C) 2018 Published by Elsevier B.V.