Thiophene-fused carbazole derivative dyes for high-performance dye-sensitized solar cells

Abstract

Two novel dyes that are similar in chemical structure, except for different donor units, AJ301 and AJ303 were synthesized, characterized and applied as sensitizers in dye-sensitized solar cells (DSSCs). Both dyes exhibited a wide absorption of visible sunlight. The introduction of fused rings on the donor unit of AJ303 presented an appropriate energy level, less recombination and longer electron lifetime to achieve a power conversion efficiency (PCE) of 10.2%, far above that achieved for AJ301 of 6.2% with a [Co(bpy) 3 ] 2+/3+ -based electrolyte under standard AM1.5G solar irradiation (100 mW cm −2 ). The DSSCs based on AJ303 and AJ301 with [Cu(tmby) 2 ] 2+/+ -based electrolyte showed a lower PCE of 8.2% and 5.4%, respectively. Therefore, the results indicated that the introduction of a fused-ring in the donor group is a meaningful synthetic strategy to improve the photovoltaic performance. • Two new metal-free dyes ( AJ301 , AJ303 ) were synthesized. • The thiophene-fused donor has more conducive to obtain higher conversion efficiency. • Both traditional cobalt electrolyte and burgeoning copper electrolyte are used in photovoltaic devices.