A Computational and Experimental Study of Thieno[3,4-b]thiophene as a Proaromatic pi-Bridge in Dye-Sensitized Solar Cells

作者：Brogdon Phillip; Giordano Fabrizio; Puneky George A; Dass Amala; Zakeeruddin Shaik M; Nazeeruddin Mohammad Khaja; Graetzel Michael; Tschumper Gregory S; Delcamp Jared H^*

来源：Chemistry - A European Journal, 2016, 22(2): 694-703.

DOI：10.1002/chem.201503187

• dye-sensitized solar cells
• NICS
• proaromaticity
• solvatochromism
• thienothiophene

Four D-pi-A dyes (D=donor, A=accpetor) based on a 3,4-thienothiophene pi-bridge were synthesized for use in dye-sensitized solar cells (DSCs). The proaromatic building block 3,4-thienothiophene is incorporated to stabilize dye excited-state oxidation potentials. This lowering of the excited-state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground- and excited-states. To avoid a necessary lowering of the TiO2 semiconductor conduction band (CB) to promote efficient dye-TiO2 electron injection, strong donor functionalities based on triaryl- and diarylamines are employed in the dye designs to raise both the ground-and excited-state oxidation potentials of the dyes. Solubility, aggregation, and TiO2 surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4-thienothiophene bridge. Power conversion efficiencies of up to 7.8% are observed.

• 出版日期2016-1-11