Influence of the Donor Size in D鈭捪€鈥揂 Organic Dyes for Dye-Sensitized Solar Cells

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• 作者：Jiabao Yang ; Paramaguru Ganesan ; Jo毛l Teuscher ; Thomas Moehl ; Yong Joo Kim ; Chenyi Yi ; Pascal Comte ; Kai Pei ; Thomas W. Holcombe ; Mohammad Khaja Nazeeruddin ; Jianli Hua ; Shaik M. Zakeeruddin ; He Tian ; Michael Gr盲tzel
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：April 16, 2014
• 年：2014
• 卷：136
• 期：15
• 页码：5722-5730
• 全文大小：592K
• 年卷期：v.136,no.15(April 16, 2014)
• ISSN：1520-5126

文摘

We report two new molecularly engineered push鈥損ull dyes, i.e., YA421 and YA422, based on substituted quinoxaline as a 蟺-conjugating linker and bulky-indoline moiety as donor and compared with reported IQ4 dye. Benefitting from increased steric hindrance with the introduction of bis(2,4-dihexyloxy)benzene substitution on the quinoxaline, the electron recombination between redox electrolyte and the TiO₂ surface is reduced, especially in redox electrolyte employing Co(II/III) complexes as redox shuttles. It was found that the open circuit photovoltages of IQ4, YA421, and YA422 devices with cobalt-based electrolyte are higher than those with iodide/triiodide electrolyte by 34, 62, and 135 mV, respectively. Moreover, the cells employing graphene nanoplatelets on top of gold spattered film as a counter electrode (CE) show lower charge-transfer resistance compared to platinum as a CE. Consequently, YA422 devices deliver the best power conversion efficiency due to higher fill factor, reaching 10.65% at AM 1.5 simulated sunlight. Electrochemical impedance spectroscopy and transient absorption spectroscopy analysis were performed to understand the electrolyte influence on the device performances with different counter electrode materials and donor structures of donor鈭捪€鈥揳cceptor dyes. Laser flash photolysis experiments indicate that even though the dye regeneration of YA422 is slower than that of the other two dyes, the slower back electron transfer of YA422 contributes to the higher device performance.