Nitroxide Radical Molecules as Highly Reactive Redox Mediators in Dye-sensitized Solar Cells
Nitroxide Radical Molecules as Highly Reactive Redox Mediators in Dye-sensitized Solar Cells
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氮氧自由基分子作为染料敏化太阳能电池中高反应性氧化还原介体
DOI：
10.1002/ange.201205036
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
H. Nishide
中科院分区：
文献类型：
--
作者：
F. Kato;A. Kikuchi;T. Okuyama;K. Oyaizu;H. Nishide
报道了有机自由基2-氮杂金刚烷-N-氧基（AZA）作为染料敏化太阳能电池（DSSC）中稳定的高活性氧化还原介体。AZA表现出适当的氧化还原电位和显着高的值的扩散，异质电子转移速率，和电子自交换反应速率。这些性质导致增强的电子转移介导，从而导致高填充因子或低电池电阻，从而获得优异的光伏性能，达到8.6%的转换效率。有机自由基通常具有高度反应性，被认为是不稳定和棘手的。然而，这些自由基中的一些已经通过化学修饰转化为稳定的化合物，以在未成对电子和/或涉及未成对电子的共振结构周围提供空间保护。[1]2，2，6，6-四甲基哌啶-N-氧自由基（克里思）是一种典型的稳定自由基，其中氧中心的未成对电子被周围的四甲基基团空间保护，并被NH 4 O基团的共振结构稳定。[2]稳定自由基在氧化还原反应中具有放电子和受电子的特性，在有机磁性领域和催化剂方面有着广泛的应用。[3]例如，克里思用作伯醇的有机、无金属氧化催化剂。[4]为了提高催化活性，2-氮杂金刚烷-N-氧基也被采用，其表现出更高的反应性，因为与克里思相比，其自由基中心周围的空间位阻降低。[5]最近，我们成功地使用在其重复单元中带有氧化还原活性克里思部分的自由基聚合物作为阴极活性有机材料，并在有机二次电池中展示了惊人的高功率速率能力。[6]分析了高充电和放电速率，并将其归因于快速的电荷传播和通过衍生自它们的克里思部分的传输。
The organic radical 2-azaadamantan-N-oxyl (AZA) used as a stable and highly reactive redox mediator in a dye-sensitized solar cell (DSSC) is reported. AZA exhibits both an appropriate redox potential and significantly high values for the diffusivity, heterogeneous electron-transfer rate, and electron self-exchange reaction rate. These properties give rise to an enhanced electron-transfer mediation which leads to a high fill factor or low cell resistance and thus excellent photovoltaic performance to achieve a conversion efficiency of 8.6%.Organic radicals are usually highly reactive and have been considered unstable and intractable. However, some of these radicals have been converted to stable compounds through chemical modification to provide steric protection around the unpaired electrons and/or resonance structures involving the unpaired electrons.[1] 2, 2, 6, 6-Tetramethylpiperidin-N-oxyl (TEMPO) is a typical example of a stable radical, in which the oxygen-centered unpaired electron is sterically protected by the surrounding tetramethyl groups and is stabilized by the resonance structure of the NÀO group.[2] Stable radicals have been studied in the field of organic magnetism and as catalytic reagents based on their unpaired electron spin and their electron-releasing and electron-accepting character in redox reactions.[3] For example, TEMPO was applied as an organic, metal-free oxidizing catalyst of primary alcohols.[4] To enhance the catalytic activity, 2-azaadamantan-N-oxyl was also employed, which exhibits a much higher reactivity because of the reduced steric hindrance around its radical center compared to that of TEMPO.[5] Recently, we successfully used radical polymers bearing redox-active TEMPO moieties in their repeating units as a cathode-active organic material and demonstrated an amazingly high power rate capability in an organic secondary battery.[6] The high charging and discharging rates were analyzed and ascribed to fast charge propagation and transport through the TEMPO moieties derived from their