Balance of catalytic activity and conductivity of Cu2ZnSnS4/graphene counter electrode for dye-sensitized solar cells: using hydrothermal-synthesized kesterite Cu2ZnSnS4 and graphene obtained by product line

Abstract

The catalytic activity and conductivity of Cu2ZnSnS4/graphene counter electrode for dye-sensitized solar cells (DSSCs) was balanced using hydrothermal-synthesized kesterite Cu2ZnSnS4 and graphene obtained by product line. It was found that the electrocatalytic activity of Cu2ZnSnS4/graphene counter electrode was adjustable by balancing its catalytic activity and conductivity using varied weight ratio of graphene in the composited material of Cu2ZnSnS4/graphene. When the weight percent of graphene was 2% to Cu2ZnSnS4, the catalytic activity and conductivity of Cu2ZnSnS4/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 Cu2ZnSnS4/graphene counter electrode show a maximum solar-to-electrical power efficiency of 3.71% (with short-circuit photocurrent density Jsc of 13.24 mA cm−2, open-circuit photovoltage Voc 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 Cu2ZnSnS4/graphene counter electrode was a little lower than that of DSSCs based on platinum (Pt) counter electrode (4.95%), it is believed that Cu2ZnSnS4/graphene counter electrode would outperform Pt counter electrode by further balancing its catalytic activity and conductivity using higher-quality and more matched Cu2ZnSnS4 and graphene. This strategy to improve the electrocatalytic activity of counter electrode will be helpful for exploring facile synthesis, low-cost, and efficient Cu2ZnSnS4-based composited counter electrode materials.