Selenization treatment on Ag8SnSxSe6-x counter electrode of dye-sensitized solar cells in improving its electron transfer and electrocatalytic activity

Abstract

In this paper, Ag8SnS6 powder was synthesized by the one-pot method, then prepared into Ag8SnS6 and Selenization treated Ag8SnSxSe6-x thin films. The effects brought by the amounts of added Se powder during the annealing process on the product phases, structures, and morphologies are characterized, and the electrochemical property and the cell efficiency as assembled into the counter electrode (CEs) for dye-sensitized solar cells (DSSCs) were investigated. It showed Se into the Ag8SnS6 lattice occupied the site of S to transform into Ag8SnSxSe6-x. And the thin film also became unflatten since the particles became larger after Se doping. The cell efficiency of Ag8SnSxSe6-x CEs reached 4.26%, which was increased by 28.31% compared to that of Ag8SnS6 CEs. Ag8SnSxSe6-x CEs performed lower charge transfer resistance (Rct) and (△EPP), and an increased△E value between the conduction band level of CEs and the redox potential of electrolyte. After 10 cycles, the almost unchanged cathode/anode current density implied the Ag8SnSxSe6-x CEs received good structure stability. Selenization treatment was able to facilitate electron transport and enhance the electrocatalytic activity, and as expected to be a promising method in improving the performance of the DSSCs.