Doping effect of copper zinc tin sulphide counter electrode for dye-sensitized solar cells

Abstract

The exploration of more efficient counter electrode (CE) is of great significance for the development of dye-sensitized solar cells (DSSCs). Here, the catalysis of I3−/I− by Cu2ZnSnS4 (CZTS) and its derivatives have been investigated using density functional theory (DFT). By studying the geometrical and electronic properties of iodine atom adsorbed on CZTS, Cu2ZnSnSxSe4−x (CZTSSe), and Cu2ZnSnSe4 (CZTSe), it was found that the charge transport performance of CZTS can be significantly enhanced when the S in CZTS was replaced by Se. Further investigation on the different cation sites of CZTS doped with K, V, Ir, or Pt reveals that the formation of V-substituted CZTS is energetically favorable. Adsorption energies of iodine atom and desorption energies of iodine anion on various surfaces were further calculated. The results indicated that the designed material shows a high catalytic activity for the reaction of I3−/I− when the Cu2 atom in CZTS is replaced by V (VCu2). Thus, the findings could help to promote novel, high-efficiency CZTS-based CE in DSSCs.