Axial-symmetric conjugated group promoting intramolecular charge transfer performances of triphenylamine sensitizers for dye-sensitized solar cells

The intramolecular charge transport (ICT) process directly determines the charge generation, transport, and even injection of the dye-sensitized solar cell (DSSC) sensitizer. Herein, we constructed a new series of D-pi-A system by linking 4-methoxyphenyl and triphenylamine donors with an ethynyl group having an axial-symmetric conjugated system. Since the axisymmetric conjugate group overcomes the reduction of the conjugate characteristic caused by the plane distortion, the molecular ICT performance and the electronic recombination inhibition are effectively improved. As a result, the photoelectric conversion efficiency was increased from 3.43% to 6.37% by means of the extension of the pi-bridge at same time. It provides a new idea for the design and development of DSSC sensitizers in the future.