Structure-Property Relationship of New Organic Sensitizers Based on Multicarbazole Derivatives for Dye-Sensitized Solar Cells.

A new multicarbazole based organic dye (C2A1, C2S1A1) with a twisted structure was designed and synthesized, and the corresponding dye (C1A1) without the twisted structure was synthesized for comparison. They were successfully applied in dye-sensitized solar cells (DSSCs). The results showed that the nonplanar structure of C2A1 and C2S1A1 can efficiently retard the dye aggregation and charge recombination. The organic dye (C2S1A1) with thiophene units also exhibited a higher molar extinction coefficient and red-shifted absorption, which leads to an improved light harvesting efficiency. The C2S1A1-sensitized solar cell produced a solar-to-electricity conversion efficiency of 5.1%, high open circuit voltage (Voc) of 0.69 V, and short-circuit photocurrent density of 10.83 mA cm-2 under AM 1.5 irradiation (100 mW cm-2) conditions. [ABSTRACT FROM AUTHOR]