Thiophene-Functionalized Porphyrins: Synthesis, Photophysical Properties, and Photovoltaic Performance in Dye-Sensitized Solar Cells

Thienyl groups were incorporated into three porphyrin dyes, ZZX-N7, ZZX-N8, and ZZX-N9, with D-π-A configuration to broaden the absorption spectra for dye-sensitized solar cells (DSCs). With the increase of π-conjugation from ZZX-N7 to ZZX-N8 to ZZX-N9, a systematic red-shift of absorption was observed. However, the broadened spectra were not correlated proportionally to their photovoltaic performance. It was found the power conversion efficiency increased in the order of ZZX-N7 ZZX-N8 > ZZX-N9 under high dye-loading condition. Further study showed that the increased EtOH/THF volume ratio in dye solution not only increased dye-loading density but also promoted dye aggregation. A trade-off between the blocking effect of the adsorbed dyes and the dye aggregation under different dye-loading densities was observed. Under optimized conditions, ZZX-N8 sensitized cell exhibited energy conversion efficiency of 7.78% u...