Cis-bis(isothiocyanato)-bis(2,2′-bipyridyl-4,4′dicarboxylato)-Ru(II) (N719) dark-reactivity when bound to fluorine-doped tin oxide (FTO) or titanium dioxide (TiO2) surfaces
Cis-bis(isothiocyanato)-bis(2,2′-bipyridyl-4,4′dicarboxylato)-Ru(II) (N719) dark-reactivity when bound to fluorine-doped tin oxide (FTO) or titanium dioxide (TiO2) surfaces
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DOI：
10.1016/j.jelechem.2010.01.004
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发表时间：
2010-03-01
影响因子：
4.5
通讯作者：
Marken, Frank
中科院分区：
文献类型：
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作者：
Fattori, Alberto;Peter, Laurence M.;Marken, Frank
太阳能电池敏化剂 cis-bis(isothiocyanato)-bis(2,2'-bipyridyl-4,4,dicarboxylato)-ruthenium(II) (N719) 在两个电极表面进行吸附和研究：(i) 裸露的掺氟氧化锡 (Fro) 和 (ii) 纳米颗粒锐钛矿 (TiO2) 薄膜 与弗罗联系。 N719 从乙腈中吸附到 Fro 表面上，从 10(-7) M 浓度开始，产生质量较差的部分或多层覆盖。相比之下，N719 Langmuirian 的 50% 乙腈 50% (BuOH)-Bu-t 溶液发生吸附，具有明确的单层覆盖和约 100% 的结合常数。 2 x 105 mol(-1) dm(3)。吸附的 N719 表现出伏安氧化/反还原响应，与 Ag/AgCl (3 M KCl) 相比，E-mid 大约为 0.56（较弱）和 0.68（主要）V，并且在足够高的扫描速率（约 16 V s(-1)）下具有化学可逆特性。涉及电极表面氧化 N719 的化学反应步骤会导致在较慢的扫描速率下电化学活性丧失，一阶化学速率常数约为 100%。 2.4 秒(-1)。完整的金属配合物 N719 和氧化后形成的反应产物都证明了碘化物的电催化氧化。当吸附到 TiO2（由直径约 9 nm 的 TiO2 颗粒制成的多孔膜，朗缪里安结合常数约 105 mol(-1) dm 3）上，浸入乙腈 (0.1 M NBu4PF6) 中，并以足够快的扫描速率（约 16 V s-1）时，N719 金属配合物表现出可逆伏安响应（E-mid 与 Ag/AgCl (3 M KCl) 相比大约为 0.68 V。在较慢的扫描速率下，伏安响应再次出现不可逆，但这一次 TiO2 表面的 N719 金属络合物没有明显降解。结果表明，由于 FTO 吸附的 N719 的降解，通过电子跳跃的传导机制变得无效。在碘化物存在下，电催化碘化物氧化过程（暗电催化）主要发生在 N719 修饰的 FTO 电极表面。讨论了这种暗反应性对太阳能电池性能的影响。 (C) 2010 Elsevier B.V. 保留所有权利。
The solar cell sensitizer cis-bis(isothiocyanato)-bis(2,2'-bipyridyl-4,4,dicarboxylato)-ruthenium(II) (N719) is adsorbed and investigated at two electrode surfaces: (i) at a bare fluorine-doped tin oxide (Fro) and (ii) at a nano-particulate anatase (TiO2) film in contact with Fro. N719 is adsorbed from acetonitrile onto Fro surfaces giving poor quality partial or multi-layer coverage commencing at 10(-7) M concentration. In contrast, from 50% acetonitrile 50% (BuOH)-Bu-t solution of N719 Langmuirian adsorption occurs with well-defined mono-layer coverage and a binding constant ca. 2 x 105 mol(-1) dm(3). The adsorbed N719 exhibits voltammetric oxidation/back-reduction responses with E-mid approximate to 0.56 (weaker) and 0.68 (dominant) V vs. Ag/AgCl (3 M KCl) and with chemically reversible characteristics at sufficiently high scan rates (ca. 16 V s(-1)). A chemical reaction step involving oxidised N719 at the electrode surface leads to the loss of electrochemical activity at slower scan rates with a first order chemical rate constant of ca. 2.4 s(-1). The electro-catalytic oxidation of iodide is demonstrated for both the intact metal complex N719 and the reaction product formed after oxidation. When adsorbed onto TiO2 (porous films made from approximately 9 nm diameter TiO2 particles, Langmuirian binding constant ca. 105 mol(-1) dm 3), immersed in acetonitrile (0.1 M NBu4PF6), and at sufficiently fast scan rates (ca. 16 V s-1), the N719 metal complex exhibits reversible voltammetric responses (with E-mid approximate to 0.68 V vs. Ag/AgCl (3 M KCl)). At slower scan rates, the voltammetric response again appears irreversible, however, this time without significant degradation of the N719 metal complex at the TiO2 surface. It is shown that the conduction mechanism via electron hopping becomes ineffective due to degradation of FTO-adsorbed N719. In the presence of iodide, the electro-catalytic iodide oxidation process (dark electro-catalysis) is shown to occur predominantly at the N719-modified FTO electrode surface. Implications of this dark-reactivity for the solar cell performance are discussed. (C) 2010 Elsevier B.V. All rights reserved.