Earth-Abundant Cobalt Pyrite (CoS2) Thin Film on Glass as a Robust, High-Performance Counter Electrode for Quantum Dot-Sensitized Solar Cells

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• 作者：Matthew S. Faber ; Kwangsuk Park ; Miguel Cab谩n-Acevedo ; Pralay K. Santra ; Song Jin
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2013
• 出版时间：June 6, 2013
• 年：2013
• 卷：4
• 期：11
• 页码：1843-1849
• 全文大小：379K
• 年卷期：v.4,no.11(June 6, 2013)
• ISSN：1948-7185

文摘

We report a cobalt pyrite (cobalt disulfide, CoS₂) thin film on glass as a robust, high-performance, low-cost, earth-abundant counter electrode for liquid-junction quantum dot-sensitized solar cells (QDSSCs) that employ the aqueous sulfide/polysulfide (S2鈥?/sup>/S_n2鈥?/sup>) redox electrolyte as the hole-transporting medium. The metallic CoS₂ thin film electrode is prepared via thermal sulfidation of a cobalt film deposited on glass and has been characterized by powder X-ray diffraction and electron microscopy. Using the CoS₂ counter electrode, CdS/CdSe-sensitized QDSSCs display improved short-circuit photocurrent density and fill factor, achieving solar light-to-electricity conversion efficiencies as high as 4.16%, with an average efficiency improvement of 54 (卤14)% over equivalent devices assembled with a traditional platinum counter electrode. Electrochemical measurements verify that CoS₂ shows high electrocatalytic activity toward polysulfide reduction, rationalizing the improved QDSSC performance. CoS₂ is also less susceptible to poisoning by the sulfide/polysulfide electrolyte, a problem that plagues platinum electrodes in this application; furthermore, CoS₂ exhibits excellent stability in sulfide/polysulfide electrolyte, resulting in highly reproducible performance.

Keywords:

quantum dot-sensitized solar cell (QDSSC); cobalt pyrite (CoS₂); sulfide/polysulfide electrolyte; photovoltaic solar energy conversion; counter electrode; electrochemistry