Abstract: Molybdenum selenide is a potential alternative to counter electrode of a platinum-free dye-sensitized solar cell (DSSC). In this work, an in situ magnetron sputtering method is developed to prepare MoSe₂ electrodes. The MoSe₂ electrodes obtained at various temperatures from 300 and 550℃ are used as counter electrode for a dye-sensitized solar cell. Photovoltaic measurement results indicate that the MoSe₂ electrodes prepared at 400℃ has the optimized performance, and the corresponding DSSCs provide an energy conversion efficiency of 6.83% which is comparable than that of the reference DSSC with platinum as counter electrode (6.51%). With further increasing the preparation temperature of the MoSe₂ electrodes, the corresponding DSSCs decrease gradually to 5.96% for 550℃. Electrochemical impedance spectra (EIS) reveal that charge transfer resistance (R_ct) of MoSe₂ electrodes is rising with increase of the temperature from 400 to 500℃, suggesting a downward electrocatalytic activity. Though the MoSe₂ electrode prepared at 550℃ show a reduced Rct, its series resistance (R_s) and diffusion resistance (Z_w) increase obviously. Considering that MoSe₂ phase cannot be formed at 300℃, it can be concluded that the prepared temperature as low as possible is favored for its final electrochemical performance. The results are very significant for developing low-cost and responsible counter electrodes for dye-sensitized solar cells.

Key words: Molybdenum selenium, Counter electrode, Electrocatalysis, Dye-sensitized solar cell, in situ synthesis, Magnetron sputtering