Facile Synthesis of Cu2SnSe3 as Counter Electrodes for Dye-Sensitized Solar Cells

Cu2SnSe3 (CTSe) nanoparticles with diameters of 150-250 nm were synthesized by a facile solvothermal method. The nanoparticles drop-casted onto fluorine dope tin oxide (FTO) substrate were used as counter electrode in dye-sensitized solar cells (DSSCs). The morphology, structure and composition of the CTSe nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and energy dispersive X-ray spectroscopy (EDS). The results indicated the formation of the nanoparticles with a single crystal phase and approximately stoichiometric composition. DSSCs fabricated with the CTSe-based counter electrodes exhibited a power conversion efficiency of 7.75%, which is similar to that of Ptbased devices (7.21%). The current-voltage curves of the DSSCs demonstrated that the thickness of the CTSe layer strongly influenced the photocurrent density and fill factor as a result of changes in the number of electrocatalytic sites and the resistance of the layers. Electrochemical impedance spectroscopy (EIS) measurements were performed and the results indicated that CTSe exhibited Pt-like electrocatalytic activity for the reduction of I3 - to I- in DSSCs. This work presents a new approach for expanding the possibilities for developing low-cost DSSCs that do not require expensive and rare Pt counter electrodes.