Joint Center for Artificial Photosynthesis and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Phys Chem Chem Phys. 2015 May 7;17(17):11908-13. doi: 10.1039/c5cp00890e.
Although titanium dioxide (TiO2) has been extensively studied and widely used in energy and environmental areas, the amorphous form and its related defect properties are poorly understood. Recent studies, however, have emphasized the crucial role of amorphousness in producing competitively good performances in photochemical applications. In this work we have investigated for the first time the effects of various dopants (B, C, N and F) on charge carrier transport in amorphous titanium dioxide (a-TiO2), given that doping is a common technique used to tune the electronic properties of semiconductors, and that the existence of these impurities could also be unintentionally introduced during the synthesis process. The a-TiO2 model was obtained using a classical molecular dynamics method, followed by density-functional theory calculations (DFT + U, with Hubbard correction term U) on electronic structures and defect states. The formation of these impurity defects in a-TiO2 was found to be energetically more favorable by several eV than their crystal counterparts (in rutile). The contributions of these defect states to the charge transfer processes were examined by means of Marcus theory.
虽然二氧化钛 (TiO2) 已经在能源和环境领域得到了广泛的研究和应用，但对于非晶态及其相关缺陷性质的了解还很有限。然而，最近的研究强调了非晶态在光化学应用中产生竞争性能的重要作用。在这项工作中，我们首次研究了各种掺杂剂（B、C、N 和 F）对非晶二氧化钛（a-TiO2）中载流子输运的影响，因为掺杂是一种常用的调节半导体电子特性的技术，而且在合成过程中这些杂质的存在也可能是无意引入的。使用经典分子动力学方法获得了 a-TiO2 模型，然后通过电子结构和缺陷态的密度泛函理论计算（DFT + U，带有 Hubbard 修正项 U）进行计算。发现这些杂质缺陷在 a-TiO2 中的形成比其晶体对应物（金红石）更有利几个电子伏特。通过马库斯理论研究了这些缺陷态对电荷转移过程的贡献。
