Synthesis of highly efficient Cu2ZnSnSxSe4−x (CZTSSe) nanosheet electrocatalyst for dye-sensitized solar cells

Abstract

Cu2ZnSnSxSe4-x (CZTSSe) has been reported as a promising platinum (Pt)-free counter electrode (CE) for dye-sensitized solar cells (DSSCs) with porous or crystalline structures. However, it is still challenging to develop a low-temperature method to synthesize CZTSSe electrodes with high surface area and excellent electrocatalytic activity. Herein, we present a low-temperature solution-phase synthetic approach to prepare self-organized CZTSSe nanosheets. As-synthesized CZTSSe nanosheets deposited on fluorine-doped tin oxide (FTO) substrate and applied as CE, yield a power conversion efficiency of (5.73%), which is comparable to the value we obtained using Pt-based CE (5.78%). In addition, CZTSSe nanosheets exhibit excellent electrocatalytic performance (4.60%) on carbon paper (CP) as a Pt/FTO-free CE. This impressive performance was attributed to the high specific surface area of CZTSSe with nanosheet morphology and related excellent electrocatalytic activity. Cyclic voltammetry and electrochemical impedance spectroscopy measurements confirmed that CE made of CZTSSe nanosheets have comparable catalytic activity with respect to Pt CE due to the low charge transfer resistance at the CE/electrolyte interface. The as-prepared CZTSSe CE with high reproducibility exhibits good chemical stability in the electrolyte containing. The low-temperature process, high surface area and high electrocatalytic activity help the CZTSSe nanosheets stand out as an alternative CE electrocatalyst in DSSC.