D-π-A Porphyrin Employing an Indoline Donor Group for High Efficiency Dye-Sensitized Solar Cells

Dye-sensitized solar cell (DSC) devices were fabricated using a novel donor-(π bridge)-acceptor (D-π-A) porphyrin sensitizer, VC-70, in which an indoline is linked directly to the porphyrin core and functions as the donor group. The best efficiencies of VC-70 and reference YD2-o-C8 devices were found to be 7.31 and 7.60%, respectively, and AMG 1.5 illumination and device properties were fully characterized using transient absorption, charge extraction, and transient photovoltage techniques. A notable effect on TiO₂ conduction band energetics and electron lifetime was observed following light soaking of VC-70 devices under AMG 1.5 illumination. Upon cosensitization of VC-70 with the organic dye D205 an improved efficiency of 8.10% was obtained.