Semiconductor Quantum Dot Sensitized Solar Cells Based on Ferricyanide/Ferrocyanide Redox Electrolyte Reaching an Open Circuit Photovoltage of 0.8 V

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• 作者：Rosemarie M. Evangelista ; Satoshi Makuta ; Shota Yonezu ; John Andrews ; Yasuhiro Tachibana
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：8
• 期：22
• 页码：13957-13965
• 全文大小：524K
• 年卷期：0
• ISSN：1944-8252

文摘

Semiconductor quantum dot sensitized solar cells (QDSSCs) have rapidly been developed, and their efficiency has recently exceeded 9%. Their performances have mainly been achieved by focusing on improving short circuit photocurrent employing polysulfide electrolytes. However, the increase of open circuit photovoltage (V_OC) cannot be expected with QDSSCs based on the polysulfide electrolytes owing to their relatively negative redox potential (around −0.65 V vs Ag/AgCl). Here, we demonstrate enhancement of the open circuit voltage by employing an alternative electrolyte, ferricyanide/ferrocyanide redox couple. The solar cell performance was optimized by investigating the influence of ferricyanide and ferrocyanide concentration on their interfacial charge transfer and transport kinetics. The optimized ferricyanide/ferrocyanide species concentrations (0.01/0.2 M) result in solar energy conversion efficiency of 2% with V_OC of 0.8 V. Since the potential difference between the TiO₂ conduction band edge at pH 7 and the electrolyte redox potential is about 0.79 V, although the conduction band edge shifts negatively under the negative bias application into the TiO₂ electrode, the solar cell with the optimized electrolyte composition has nearly reached the theoretical maximum voltage. This study suggests a promising method to optimize an electrolyte composition for maximizing solar energy conversion efficiency.