Abstract
A series of metal-free organic dyes (TPA1-TPA5) comprising triphenylamine as electron donor, cyanoacrylic acid as anchoring group and oligocenothiophene-pyrimidine as pi-bridge linkers were molecularly engineered. By incorporation and elongation of oligocene spacer between donor and acceptor, electronic structures, photovoltaic and optoelectronic properties were tuned. Electronic and optical properties calculations of TPA dye upon adsorbing onto Ti3O6H and Ti6O12H were performed systematically. The charge transfer from occupied to unoccupied molecular orbitals in unaccompanied dyes and TPA@TiO2 clusters, broad and long range spectral peaks affirmed that linkers elongation enhance electron injection (Delta G(inject)) and electronic coupling constants (vertical bar V-RP vertical bar). Tailoring the energy gap by elevating HOMO and lowering LUMO energy levels as well as fostering Delta G(inject), oligocene elongation was commenced excellent linkers. The superior photovoltaic parameters than referenced compounds, frontier molecular orbitals analyses and charge transfer nature in TPA@TiO2 clusters are illuminating that these dyes would be efficient to be used in photovoltaic devices.