Cu₂ZnSnS₄/N-MWCNTs hybrid systems as counter electrode substitutes for platinum in dye-sensitized solar cells

Copper zinc tin sulfide, Cu₂ZnSnS₄ (CZTS) is being considered a viable option for a counter electrode due to its abundance, cost-effectiveness, catalytic activity, and other advantageous properties. However, CZTS has low electron transport capabilities, a shortcoming that can be addressed by combining it with high electron mobility carbon nanomaterials. Nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) exhibit higher electron conductivities than their pristine counterparts. This improvement is attributed to the disruption of the sp²-hybridized carbon arrangement, as some of the carbon atoms are replaced by nitrogen atoms. In this study, a counter electrode composed of a 70% CZTS and 30% N-MWCNTs mixture produced a higher electrochemical current density compared to the individual materials. This suggests that it is more electrocatalytic than CZTS and N-MWCNTs alone, ultimately leading to the highest power conversion efficiency of 6.52%.