Abstract

The catalytic activity and conductivity of Cu 2 ZnSnS 4 /graphene counter electrode for dye-sensitized solar cells (DSSCs) was balanced using hydrothermal-synthesized kesterite Cu 2 ZnSnS 4 and graphene obtained by product line. It was found that the electrocatalytic activity of Cu 2 ZnSnS 4 /graphene counter electrode was adjustable by balancing its catalytic activity and conductivity using varied weight ratio of graphene in the composited material of Cu 2 ZnSnS 4 /graphene. When the weight percent of graphene was 2% to Cu 2 ZnSnS 4 , the catalytic activity and conductivity of Cu 2 ZnSnS 4 /graphene counter electrode came to the balanced point, resulting in the best electrocatalytic activity. Under the balanced conditions, the dye-sensitized solar cell devices based on Cu 2 ZnSnS 4 /graphene counter electrode show a maximum solar-to-electrical power efficiency of 3.71% (with shortcircuit photocurrent density J sc of 13.24 mA cm −2 , open-circuit photovoltage V oc of 0.63 V, and fill factor FF of 0.44), which is higher than that of unbalanced counter electrode. Although the photovoltaic performance of DSSCs based on Cu 2 ZnSnS 4 / graphene counter electrode was a little lower than that of DSSCs based on platinum (Pt) counter electrode (4.95%), it is believed that Cu 2 ZnSnS 4 /graphene counter electrode would outperform Pt counter electrode by further balancing its catalytic activity and conductivity using higher-quality and more matched Cu 2 ZnSnS 4 and graphene. This strategy to improve the electrocatalytic activity of counter electrode will be helpful for exploring facile synthesis, low-cost, and efficient Cu 2 ZnSnS 4 -based composited counter electrode materials. Keywords Dye-sensitized solar cells . Cu 2 ZnSnS 4 /graphene composited materials . Counter electrode . Balance of catalytic activity and conductivity . Electrocatalytic activity Dedicated to the memory of Ivo Alexandre Hümmelgen