Relaxation dynamics of ruthenium complexes in solution, PMMA and TiO2 films:: The roles of self-quenching and interfacial electron transfer
Relaxation dynamics of ruthenium complexes in solution, PMMA and TiO2 films:: The roles of self-quenching and interfacial electron transfer
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DOI：
10.1021/jp073843m
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发表时间：
2007-09-06
影响因子：
3.7
通讯作者：
Diau, Eric Wei-Guang
中科院分区：
文献类型：
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作者：
Chang, Chih-Wei;Chou, Chung Kuang;Diau, Eric Wei-Guang
用时间分辨发射光谱和飞秒瞬态吸收光谱研究了两种过渡金属配合物[Ru(bpy)(3)]（2+）和[Ru(bpy)(3)(mcbpy)]（2+）在乙醇溶液和聚甲基丙烯酸甲酯（PMMA）和TiO2薄膜中的弛豫动力学。测定脱气[Ru(bpy)3]21溶液在乙醇中的发射寿命为700 ns；为了描述聚集引起的自猝灭动力学，得到了[Ru(bPY)(3)](2+)/PMMA薄膜的三个衰减系数，分别为5.3、70和220 ns。在[Ru(bpy)(3)](2+)/TiO2薄膜中，电子在空间上的转移与固体薄膜中的本征系统间交叉（类似于100 fs）和振动弛豫（类似于6 ps）相竞争。对于[Ru(bpy)(2)(mcbpy)](2+)/TiO2薄膜，虽然电子通过键转移的弛豫比电子通过空间转移的弛豫快，但两者发生在相似的时间尺度上。通过飞秒瞬态吸收测量，我们为界面电子正向和反向转移提供了重要的动力学证据。我们得出结论，在染料敏化太阳能电池应用中，界面电子转移过程不仅通过键，而且通过空间也很重要。
The relaxation dynamics of two transition-metal complexes, [Ru(bpy)(3)](2+) and [Ru(bpy)(3)(mcbpy)](2+), in ethanol solution and in poly(methyl methacrylate) (PMMA) and TiO2 films have been investigated with time-resolved emission and femtosecond transient absorption spectroscopy. The emission lifetime of a degassed [Ru(bpy)3]21 solution in ethanol was determined to be 700 ns; to describe the self-quenching kinetics due to aggregation, three decay coefficients, 5.3, 70, and 220 ns, were obtained for the [Ru(bPY)(3)](2+)/PMMA film. The electron transfer through space in a [Ru(bpy)(3)](2+)/TiO2 film competed with intrinsic intersystem crossing (similar to 100 fs) and vibrational relaxation (similar to 6 ps) in solid films. For the [Ru(bpy)(2)(mcbpy)](2+)/TiO2 film, although the relaxation for electron transfer through bonds was more rapid than electron transfer through space, both processes occur on similar time scales. Through ferntosecond transient absorption measurements, we provide important dynamical evidence for the interfacial electron transfer in both forward and backward directions. We conclude that in dye-sensitized solar-cell applications processes for interfacial electron transfer are significant not only through bonds but also through space.