High-efficient dye-sensitized solar cells with all-inorganic Cu2ZnSnSe4 counter-electrode by ligand exchange

For the first time, we synthesized all-inorganic Cu2ZnSnSe4 nanocrystals (CZTSe NCs) by ligand exchange strategy using a simple metal-free chalcogenide compound [(NH4)2S] as the inorganic ligand. The results of I-V and Hall-effect measurement illuminated that all-inorganic CZTSe films reveal the excellent electron-transfer performance. When the all-inorganic CZTSe NCs films used as counter electrode (CE) in dye-sensitized solar cells (DSSCs), the photocurrent density increases significantly from 4.48 (OLA-capped CZTSe NCs) to 14.17 mA/cm2 (all-inorganic CZTSe NCs). A higher efficiency of η = 7.06% was achieved for all-inorganic CZTSe films as CE in DSSCs. The photovoltaic results showed that high temperature annealing can be avoided for all-inorganic CZTSe films as CE. Cyclic voltammetry (CV) results and electrochemical impedance spectroscopy (EIS) showed the all-inorganic CZTSe films as CE exhibited good electrocatalytic activity and high conductivity, which demonstrated that all-inorganic CZTSe NCs would serve as an effective CE material in DSSCs.