Ultrafast stepwise electron injection from photoexcited Ru-complex into nanocrystalline ZnO film via intermediates at the surface
Ultrafast stepwise electron injection from photoexcited Ru-complex into nanocrystalline ZnO film via intermediates at the surface
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DOI：
10.1021/jp034039c
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发表时间：
2003-05-01
影响因子：
3.3
通讯作者：
Tachiya, M
中科院分区：
文献类型：
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作者：
Furube, A;Katoh, R;Tachiya, M
通过观察可见光和近红外（600-2000 nm）范围内的飞秒瞬态吸收，研究了光激发Ru配合物顺式二（4，4 '-二羧基-2，2'-联吡啶）二硫氰基钌（II）[Ru（dcbpy）（2）（NCS）（2）]（N3）对纳米ZnO薄膜的超快电子注入过程.在吸附的N3染料的金属-配体电荷转移带的光激发之后，在小于100 fs的时间内，在600至1500 nm的范围内具有在约1200 nm处的最大值的非常宽的瞬态吸收带上升。随后，近红外吸收带呈现多指数衰减，时间常数分别为5 ps、150 ps和> 1 ns，导致产生在2000 nm附近吸收的导电电子。因此，这一初始宽带被认为是由于电子从激发态N3到ZnO导带的转移过程中的中间体。1200 nm附近的宽吸收带的起源进行了讨论，在激发的N3染料和ZnO的表面状态之间的电荷转移络合物。
Ultrafast electron injection processes from photoexcited Ru-complex, cis-bis-(4,4'-dicarboxy-2,2'-bipyridine)dithiocyanato ruthenium(II), [Ru(dcbpy)(2)(NCS)(2)] (N3), into nanocrystalline ZnO film have been investigated by observing the femtosecond transient absorption in the visible and near-IR range (600-2000 nm). After photoexcitation of the metal-to-ligand charge-transfer band of the adsorbed N3 dye, a very broad transient absorption band ranging from 600 to 1500 nm having a maximum at around 1200 nm rose in less than 100 fs. Subsequently, the absorption band in the near-IR showed a multiexponential decay with time constants of similar to5 ps, similar to150 ps, and > 1 ns, leading to the generation of conductive electrons which absorb at around 2000 nm. Therefore, this initial broad band is considered to be due to the intermediates during the electron transfer from excited N3 to the conduction band of ZnO. The origin of the broad absorption band around 1200 nm is discussed in terms of a charge-transfer complex between the excited N3 dye and surface states of ZnO.