Two Novel Carbazole Dyes for Dye-Sensitized Solar Cells with Open-Circuit Voltages up to 1 V Based on Br-/Br3- Electrolytes

Dye-sensitized solar cells (DSCs) based on two novel carbazole dyes (TC301 and TC306) and a Br-/Br-3(-) redox mediator in dried CH3CN solutions as electrolytes yielded a V-oc of 1.156 V and a eta value of 3.68% and a V-oc of 0.939 V and a eta value of 5.22% under simulated AM 1.5, respectively. The dyes TC301 and TC306 have more positive HOMO levels (1.59 and 1.38 V vs NHE) than the redox potential of Br-/Br-3(-)-based electrolytes, which have sufficient driving force to regenerate dyes. Under similar conditions with an I-/I-3(-) instead of a Br-/Br-3(-) redox mediator, DSCs sensitized by the dyes TC301 and TC306 produced a V-oc of 0.696 V and a eta value of 2.36% and a V-oc of 0.621 V and a eta value of 4.10%, respectively.