Interfacial charge-transfer transitions in a TiO2-benzenedithiol complex with Ti-S-C linkages
Interfacial charge-transfer transitions in a TiO2-benzenedithiol complex with Ti-S-C linkages
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DOI：
10.1039/c5cp05046d
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Hanaya, Minoru
中科院分区：
文献类型：
--
作者：
Fujisawa, Jun-ichi;Muroga, Ryuki;Hanaya, Minoru
有机材料与无机半导体之间的界面电荷转移（ICT）跃迁是有机-半导体界面光吸收的一种新机制。ICT转变导致一步界面电荷分离而没有能量损失。这一特征对于实现高效的有机-无机杂化太阳能电池具有潜在的用途。ICT转换已被检查通过采用二氧化钛（TiO 2）纳米粒子化学吸附与p-共轭分子通过Ti-O-C键。在这里，我们报告ICT过渡在二氧化钛和1，2-苯二硫醇（BDT）与Ti-S-C键的复合物。BDT通过硫原子与表面钛原子的桥连双齿配位吸附在TiO 2上。TiO 2-BDT复合物在可见光区表现出从BDT部分到TiO 2导带的ICT跃迁。ICT转变通过表面钛原子的d轨道与苯环的p轨道之间的轨道重叠而发生。我们的密度泛函理论（DFT）分析表明，硫桥原子的3 p价轨道贡献了超过50%的最高占据分子轨道（HOMO），并且与通过Ti-O-C键的3d-2 p（氧）-p相比，通过Ti-S-C键的3d-3 p（硫）-p相互作用增强了钛原子与苯部分之间的电子混合。这一结果表明，重要的作用，强的有机-无机电子耦合的双原子连接。
Interfacial charge-transfer (ICT) transitions between organic materials and inorganic semiconductors are a new mechanism for light absorption at organic-semiconductor interfaces. ICT transitions cause one-step interfacial charge separation without loss of energy. This feature is potentially useful to realize efficient organic-inorganic hybrid solar cells. ICT transitions have been examined by employing titanium dioxide (TiO2) nanoparticles chemisorbed with p-conjugated molecules via Ti-O-C linkages. Here, we report ICT transitions in a TiO2 and 1,2-benzenedithiol (BDT) complex with Ti-S-C linkages. BDT adsorbs on TiO2 by the bridging bidentate coordination of the sulfur atoms to surface titanium atoms. The TiO2-BDT complex shows ICT transitions from the BDT moiety to the conduction band of TiO2 in the visible region. The ICT transitions occur by orbital overlaps between the d orbitals of the surface titanium atoms and the p orbitals of the benzene ring. Our density-functional-theory (DFT) analysis reveals that the 3p valence orbitals of the sulfur bridging atoms contribute to more than 50% of the highest occupied molecular orbital (HOMO) and the 3d-3p(sulfur)-p interaction via the Ti-S-C linkage enhances the electronic mixing between the titanium atoms and the benzene moiety as compared to the 3d-2p(oxygen)-p via the Ti-O-C linkage. This result indicates the important role of the heavier-atom linkers for strong organic-inorganic electronic couplings.