Effect of Anchoring Group in Anthracene/Thiophene-Bridged Triphenylamine-Based Organic Dyes for Dye-Sensitized Solar Cells

Triphenylamine-based metal-free organic dyes (D1D3) with different electron acceptors such as 2-cyanoacetic acid, rhodanine-3-acetic acid, or 5-oxo-1-phenyl-2-pyrazolin-3-carboxylic acid connected through anthracene and thiophene pi-spacers were synthesized and applied in dye-sensitized solar cells. The photophysical and electrochemical properties of these dyes were investigated and their performance as sensitizers in dye-sensitized solar cells was evaluated. Electrochemical studies showed that the lowest unoccupied molecular orbital energy levels can be tuned by introduction of various anchoring groups with different electron withdrawing abilities. The power conversion efficiencies of the dye-sensitized solar cells based on D1D3 decreased as the electron withdrawing ability of their anchoring groups increased in the order D1 < D2 < D3. The D1-based device showed the highest power conversion efficiency (1.27%).