Modified Hagfeldt Donor for Organic Dyes That Are Compatible with Copper Electrolytes in Efficient Dye-Sensitized Solar Cells

A series of anthracene-based LC dyes featuring modified bulky Hagfeldt donors have been designed and synthesized for copper electrolyte-based dye-sensitized solar cells (DSSCs). In the LC dyes, two more alkoxy chains are introduced into phenyl substituents in the well-known Hagfeldt donor framework to further attenuate charge recombination in DSSCs, which is demonstrated by photovoltaic and electrochemical studies. LC4-based DSSCs fabricated with the CuI/II(dmp)2(TFSI)1/2 (dmp = 2,9-dimethyl-1,10-phenanthroline, TFSI = bis(trifluoromethylsulfonyl)imide) electrolyte exhibit a high open circuit voltage (VOC = 1.095 V), short-circuit photocurrent (JSC = 10.500 mA cm-2), fill factor (FF = 0.757), and power conversion efficiency (PCE = 8.70%), which are better than those of its counterpart TY6 with a PCE of 5.66% (JSC = 8.637 mA cm-2, VOC = 1.048 V, FF = 0.626), demonstrating that the modified bulky donor is a promising building block for organic sensitizers.