Mechanisms of instability in Ru-based dye sensitization solar cells
Mechanisms of instability in Ru-based dye sensitization solar cells
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DOI：
10.1021/jp9624919
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发表时间：
1997-04-03
影响因子：
3.3
通讯作者：
Tributsch, H
中科院分区：
文献类型：
--
作者：
Grunwald, R;Tributsch, H
使用全反射技术对钌络合物敏化湿式太阳能电池进行的原位红外研究表明，附着在 TiO2 上的钌络合物（三核和单核）在碘化物或纳米晶 TiO2 孔内氧化物再生不充分的情况下会发生光电化学转化并不可逆地消耗。敏化剂[(Ru(bpy)(2)(CN)(2))(2)Ru(bpca)(2)](2-)（bpy是2,2'-联吡啶，bpca是2,2'-联吡啶-4,4'-二羧酸酯）分解成碎片；其中之一被鉴定为Ru(bpy)(2)(CN)(2)。对于敏化剂Ru(bpca)(2)(SCN)(2)，显示产生了分子碎片（在2013 cm(-1)处吸收），该分子碎片从纳米结构TiO2层中扩散出来。由于其与光电流密度的相关性，它被鉴定为氧化敏化剂的产物。由于全反射元件引入的高串联电阻以及导致原位测量期间敏化单元的低填充因子，只有小光电流（5-10 μ A cm(-2)）可以通过敏化界面。由于产物形成速率应与光电流密度与碘化物浓度之比成正比，因此与太阳能电池中的条件（10 mA cm(-2), 1 M）相比，碘化物浓度相应降低（1-10 mM）。由于密封问题，生产稳定敏化太阳能电池的努力被证明是不成功的，因此开发了这种光谱技术。我们的实验似乎不允许外推至 10(7)-10(8) 电子转移数来敏化 Ru 配合物，并且需要真正的长期测试来重新评估长期性能。
In-situ infrared studies performed with operating Ru-complex-sensitized wet solar cells using a total reflection technique reveal that the ruthenium complex (both tri- and mononuclear) attached to TiO2 is photoelectro-chemically transformed and irreversibly consumed under conditions of insufficient regeneration by iodide or from the oxide within the nanocrystalline TiO2 pores. The sensitizer [(Ru(bpy)(2)(CN)(2))(2)Ru(bpca)(2)](2-) (bpy is 2,2'-bipyridine, bpca is 2,2'-bipyridine-4,4'-dicarboxylate) decomposes into fragments; one of them was identified to be Ru(bpy)(2)(CN)(2). For the sensitizer Ru(bpca)(2)(SCN)(2), it is shown that a molecular fragment (absorbing at 2013 cm(-1)) is generated which is diffusing out of the nanostructured TiO2 layer. Due to its correlation with the photocurrent density, it is identified as a product of the oxidized sensitizer. Due to a high serial resistance introduced by the total reflection element and the resulting low fillfactor of the sensitization cell during in-situ measurements, only small photocurrents (5-10 mu A cm(-2)) could be passed through the sensitizing interface. Since the rate of product formation should be proportional to the ratio of photocurrent density to iodide concentration, the iodide concentration was correspondingly reduced (1-10 mM) as compared to the conditions in a solar cell (10 mA cm(-2), 1 M). This spectroscopic technique was developed because efforts to produce stable sensitization solar cells proved to be unsuccessful due to sealing problems. Our experiments do not seem to permit extrapolation to 10(7)-10(8) electron transfer numbers for sensitizing Ru complexes, and real long-term testing is required for reevaluating long-term performance.