Electrocatalytically active MoSe2 counter electrode prepared in situ by magnetron sputtering for a dye-sensitized solar cell

磁控溅射法原位制备电催化活性的MoSe2用于染料敏化太阳能电池对电极（英文）

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(Rct) 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(Rs) and diffusion resistance(Zw) 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.

采用低成本材料取代铂对电极对于染料敏化太阳能电池的发展非常重要.金属硫族化合物MoSe2对于I3?的还原反应具有电催化活性,有望用作染料敏化太阳能电池对电极材料.而除了材料本身,电极的制作能够直接影响其电催化活性和稳定性.本文报道一种采用磁控溅射在FTO导电玻璃基底上原位制备MoSe2电极的方法,并考察其作为对电极的综合性能.制备过程中,首先将硒刮涂在基底,接着在上层磁控溅射金属钼,然后于不同温度下在氩气氛中焙烧制得MoSe2对电极.详细研究了焙烧温度对MoSe2对电极结构、形貌,及其对最终电池性能的影响.形貌分析结果显示,所获得的MoSe2呈现纳米板状形态,厚度约为20 nm,直径约为100 nm,纳米板交织成一层MoSe2膜,平均厚度约为1.3μm.光伏测量结果表明,当焙烧温度在400和450℃时的电池效率分别是6.83%和6.68%,与传统的Pt作对电极时的效果(6.51%)相近.随着MoSe2电极的制备温度进一步提高,相应的DSSC在550℃时逐渐降低至5.96%.对于层状MoSe2,其对于I3?的电催化还原活性位处于层状结构的边缘面(100晶面),而非基面(002晶面),合适的焙烧温度能够使对电极中MoSe2暴露更多的活性位点.电化学阻抗谱显示,MoSe2电极的电荷转移电阻(Rct)随温度从400℃增加到500℃而升高,表明电催化活性下降.虽然在550℃下制备的MoSe2电极显示出降低的Rct,但其串联电阻和扩散电阻明显增加.考虑到MoSe2相不能在300℃下形成,可见,尽可能低的制备温度有利于提高其最终的电化学性能.