Novel D-pi-A carbazole sensitizers with 4-phenyl-2-(thiophen-2-y1) thiazole as pi-bridge for dye-sensitized solar cells

A class of novel carbazole sensitizers was synthesized with carbazole derivatives as the electron donor, 4-phenyl-2-(thiophen-2-yl) thiazole as pi-bridge and cyanoacetic acid as the electron acceptor. Their absorption spectra, photovoltaic performance and electrochemical properties were evaluated. These carbazole sensitizers share the same pi-bridge and electron acceptor and display the similar absorption spectra. However, the differences in link mode and substituent bring about the absorptivity variation. It is observed that the link mode of pi-bridge at the benzene ring instead of N atom of the carbazole unit favors improving the light absorptivity and lowering the charge recombination. Those carbazole sensitizers show the optimal photovoltaic performance with a J(sc) of 10.01 mA/cm(2),V-oc of 0.66V, and ff of 0.72, corresponding to an overall conversion efficiency eta of 4.72% under standard AM 1.5G irradiation. (C) 2015 Elsevier B.V. All rights reserved.