Influence Of The Auxiliary Acceptor And Pi-Bridge In Triarylamine Dyes On Dye-Sensitized Solar Cells

Four metal-free organic dyes (AFL7-AFL10) based on triarylamine donors and different pi-bridges with or without a benzothiadiazole auxiliary acceptor have been synthesized. The dyes' photophysical and electrochemical properties, theoretical calculations, and dye-sensitized solar cell (DSSC) performances have been investigated. Electrochemical measurement data indicate that varying the pi-conjugacy system can tune the HOMO and LUMO energy levels. A high molar extinction coefficient combined with a broad absorption spectrum helps to reinforce the dyes' light harvesting ability; therefore, it could help to increase the J(SC) of the DSSCs. Among the four dyes, AFL7 bearing the bithiophene bridge achieves the best photocurrent performance with a J(SC) value of 16.94 mA cm(-2), corresponding to an overall conversion efficiency eta of 7.92% under standard AM 1.5 G conditions (that of N719 dye was 8.53% under the same conditions). The results show that the dyes based on the triarylamine donor containing fluorenyl and biphenyl moieties are promising candidates for improving the performance of DSSCs.