Parasitic Absorption and Internal Quantum Efficiency Measurements of SolidState Dye Sensitized Solar Cells

The internal quantum effi ciency (IQE) of solid-state dye sensitized solar cells (ssDSCs) is measured using a hybrid optical modeling plus absorptance measurement approach which takes into account the parasitic absorption of the hole transport material (HTM). Across device thicknesses of 1 to 4 microns, ssDSCs sensitized with Z907 and TT1 dyes display relatively constant IQEs of approximately 88% and 36%, respectively, suggesting excellent charge collection effi ciencies for both dyes but poor carrier injection for TT1 devices. The addition of more coadsorbent is shown to increase the IQE of TT1 up to approximately 58%, but signifi cantly lowers dye loading. Finally, optical losses due to absorption by the HTM are quantifi ed and found to be a signifi cant contribution to photocurrent losses for ssDSCs sensitized with poor absorbers such as Z907, as the weak absorption of the dye gives the HTM opportunity for signifi cant parasitic absorption within the active layer.