Anthracene Organic Sensitizer with Dual Anchors for Efficient and Robust Dye-Sensitized Solar Cells

Two dyes DY1 and DY2 featuring 1,2-di(anthracene-9-yl)ethyne as an extended π-conjugated spacer and an N, N-diarylamino group as the donor have been designed and synthesized for application in dye-sensitized solar cells. On the other side of 1,2-di(anthracene-9-yl)ethyne, DY1 contains one carboxylic acid as the anchoring group at 10-position of anthracene, whereas the structural analogue DY2 has dual carboxylic acid groups at 4, 5-positions of anthracene as the anchors for binding to TiO2. With the introduction of dual carboxyl anchors, the higher dipole moment of the molecule may induce relatively high local I– concentration at the interface to reduce the oxidized dye (D+); thus, the DY2-based device has the highest short-circuit current (JSC). For open-circuit voltage (VOC), both DY1- and DY2-based devices have close VOC owing to their structures resembling CW6. For the DY2-based device, the power conversion efficiency of DSCs was η = 6.96% under simulated one-sun AM 1.5 G illumination with JSC = 13.08 mA cm–2, VOC = 0.73 V, and FF = 0.73, which is considerably higher than that of the DY1-based device with η = 5.71%, JSC = 10.70 mA cm–2, VOC = 0.72 V, and FF = 0.74, whereas the reference dye CW6 exhibited a cell performance of η = 6.96%, JSC = 11.50 mA cm–2, VOC = 0.78 V, and FF = 0.78. Besides, the dual anchoring dye, DY2-based device exhibited better stability than the others.