Abstract
Donor-bridge-acceptor (D-pi-A) compounds have garnered significant attention, and have led to increased efficiency of photovoltaic devices. In this study, an effective D-pi-A dye (TPA-PT) was designed that contains tri-phenyl-amine, thiophene-pyrimidine and cyanoacetic acid as donor (D), pi-bridge and acceptor (A), respectively. The TPA-PT was adsorbed on the semiconductor surfaces, i.e., Ti3O6H and Ti6O12H clusters, and light was shed on the adsorption behavior by bidentate bridging @Ti3O6H and chelating @Ti6O12H modes. The frontier molecular orbitals (FMOs) and structural and optical properties are studied by applying density functional theory (DFT) and time-dependent DFT (TD-DFT). Important parameters including charge transfer mechanism, electronic coupling constants (vertical bar V-RP vertical bar), band alignment, electron injection (Delta G(inject)), relative electron injection (Delta G(r)(inject)) and light-harvesting efficiency are comprehensively investigated. The charge transfer from TPA-PT dye to the semiconductor surface of Ti3O6H and Ti6O12H clusters is explored as well. Additionally, the computed values of open-circuit photo-voltage (V-oc) are presented for two cases of TiO2 and PCBM.