Colloidal synthesis of Cu2FeSnSe4 nanocrystals for solar energy conversion

• Cu2FeSnSe4 nanocrystals, which possessed a optical band gap value of 1.60±0.02 eV, were synthesized by a hot-injection method.
• The Cu2FeSnSe4 thin film prepared by drop-casting nanocrystals ink shows clear and stable photo-electrochemical response.
• Our work illustrates that Cu2FeSnSe4 nanocrystals have great potential application in the field of solar energy conversion.

Cu2FeSnSe4 (CFTSe) nanocrystals have been synthesized by a hot-injection method. The structure of prepared CFTSe nanocrystals is determined by XRD, high resolution TEM image, and SAED pattern. The composition of the CFTSe nanocrystals is confirmed from the results of EDS and XPS. Results clearly prove the formation of CFTSe nanocrystals using the hot-injection method in this study. A band gap of 1.60±0.02 eV for CFTSe nanocrystals is obtained from the UV–vis–NIR data. Moreover, the corresponding CFTSe nanocrystals-film shows a clear photoresponse in photoelectrochemical measurement. Our work illustrates that CFTSe nanocrystals have potential application in the field of solar energy conversion.