The Role of Mott-Schottky Heterojunctions in Ag-Ag8SnS6 as Counter Electrodes in Dye-Sensitized Solar Cells

Well-defined uniform pyramidal Ag-Ag8SnS6 heterodimers are prepared via a one-pot method. A plausible formation mechanism for the unique structures based on a seed-growth process and an etching effect due to oleylamine is proposed. The formed metal-semiconductor Mott-Schottky heterojunction promotes electron transfer from semiconducting Ag8SnS6 to metallic Ag, which catalyzes the reduction of I-3(-) to I-. When used as counter electrode in dye-sensitized solar cells, the heterodimers show comparable performance to platinum.