Capturing transiently charged states at the C60/TiO2(110) interface by time-resolved soft X-ray photoelectron spectroscopy
Capturing transiently charged states at the C60/TiO2(110) interface by time-resolved soft X-ray photoelectron spectroscopy
复制标题
通过时间分辨软 X 射线光电子能谱捕获 C60/TiO2(110) 界面的瞬态带电状态
DOI：
10.1016/j.orgel.2016.01.020
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发表时间：
2016
影响因子：
3.2
通讯作者：
Iwao Matsuda
中科院分区：
文献类型：
--
作者：
Kenichi Ozawa;Susumu Yamamoto;Ryu Yukawa;Kazuma Akikubo;Masato Emori;Hiroshi Sakama;Iwao Matsuda
利用时间分辨软X射线光电子能谱技术研究了C60/TiO 2（110）界面的能级排列和光激发载流子动力学。界面电子结构的特征在于由II型结，这有利于从C60到TiO 2的光激发电子的注入。紫外（UV）激光脉冲辐照诱导C 1 s和Ti 2 p核心能级向更高结合能的瞬态位移。这些能量转移是由C60层和TiO 2（110）表面之间的激光诱导电荷转移引起的。在紫外吸收时，C60的价电子被提升到未被占据的能级，然后共振转移到TiO 2，使C60处于阳离子化状态。在TiO 2（110）侧，电子被注入到导带中以提高载流子密度，从而引起TiO 2带向下弯曲。C60和TiO 2的紫外激发态的寿命比固体C60中电子-空穴对的寿命长得多。因此，C60/TiO 2（110）界面被证明对于分离C60层内产生的电子-空穴对是有效的。
Time-resolved soft X-ray photoelectron spectroscopy is utilized to determine an energy level alignment and the photoexcited carrier dynamics at a C60/TiO2(110) interface. The interface electronic structure is characterized by a type II junction, which favors an injection of photoexcited electrons from C60to TiO2. Ultraviolet (UV) laser pulse irradiation induces transient shifts of both C 1s and Ti 2p core levels towards the higher binding energies. These energy shifts are caused by a laser-induced charge transfer between the C60layer and the TiO2(110) surface. Upon UV absorption, valence electrons of C60are promoted to unoccupied levels, followed by a resonant transfer to TiO2, leaving C60in a cationized state. On the TiO2(110) side, the electrons are injected into the conduction band to raise the carrier density so that downward bending of the TiO2band is induced. The UV-excited states of C60and TiO2have sufficiently longer lifetime than the lifetime of the electron–hole pairs in solid C60. The C60/TiO2(110) interface is, thus, proved to be efficient for separating the electron–hole pairs generated within the C60layer.