Persson Petter, Lundqvist Maria J
Department of Quantum Chemistry, Uppsala University, Box 518, SE-751 20 Uppsala, Sweden.
J Phys Chem B. 2005 Jun 23;109(24):11918-24. doi: 10.1021/jp050513y.
Structural and electronic properties of a small anatase TiO2 nanocrystal sensitized by the ruthenium dye N3 (Ru(4,4'-dicarboxy-2,2'-bipyridine)2(NCS)2) have been investigated using density functional theory (DFT) with support from Hartree-Fock (HF) and time dependent DFT (TD-DFT) calculations. Significant structural adjustments of both the dye and the nanocrystal are predicted to be induced by the strain imposed by the simultaneous formation of multiple dye-surface bonds. Electronic properties of the combined dye-nanocrystal system have also been calculated, including information about interfacial orbital mixing and the lowest excited singlet states. Ultrafast photoinduced electron transfer processes across the dye-nanoparticle interface in dye-sensitized solar cells are finally discussed in view of estimated electronic coupling strengths. The calculations predict injection times on the order of 10 fs for MLCT excitations to the ligand pi* levels that interact most strongly with the TiO2 conduction band, and an order of magnitude increase in the injection times for excitations to dye levels with poor spatial or energetic overlaps with the substrate conduction band.
利用密度泛函理论（DFT），并辅以哈特里-福克（HF）和含时密度泛函理论（TD-DFT）计算，研究了由钌染料N3（Ru(4,4'-二羧基-2,2'-联吡啶)2(NCS)2）敏化的小锐钛矿型TiO2纳米晶体的结构和电子性质。预计多个染料-表面键同时形成所施加的应变会引起染料和纳米晶体的显著结构调整。还计算了染料-纳米晶体组合体系的电子性质，包括有关界面轨道混合和最低激发单重态的信息。最后，鉴于估计的电子耦合强度，讨论了染料敏化太阳能电池中跨染料-纳米颗粒界面的超快光致电子转移过程。计算预测，对于与TiO2导带相互作用最强的MLCT激发到配体π*能级，注入时间约为10 fs，而对于与底物导带空间或能量重叠较差的染料能级激发，注入时间会增加一个数量级。
