Electronic and optical properties of doped TiO2 by many-body perturbation theory
Electronic and optical properties of doped TiO2 by many-body perturbation theory
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DOI：
10.1103/physrevmaterials.3.045401
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发表时间：
2019-04-02
影响因子：
3.4
通讯作者：
Selloni, Annabella
中科院分区：
文献类型：
--
作者：
Atambo, Michael O.;Varsano, Daniele;Selloni, Annabella
掺杂是改善TiO 2光催化和太阳能转换性能的最常见策略之一，因此掺杂TiO 2的电子和光学性质的准确理论描述具有科学和实际意义。在这项工作中，我们使用多体微扰理论技术来研究两个典型的n型掺杂剂，铌和氢，在二氧化钛金红石。使用GW近似来确定带边和缺陷能级，以及用于计算吸收光谱的Bethe-Salpeter方程，我们发现缺陷能级形成非色散带，其位于相应价带顶部上方类似于2.2 eV（类似于原始材料导带下方0.9 eV）。缺陷态也是导致低能量吸收峰出现的原因，这些吸收峰增强了金红石的太阳光谱吸收。与这些低能量激发相关联的激子波函数的空间分布对于两种掺杂剂是非常不同的，这表明在Nb-TiO 2中的光激发电子的更大的迁移率。
Doping is one of the most common strategies for improving the photocatalytic and solar energy conversion properties of TiO2, hence an accurate theoretical description of the electronic and optical properties of doped TiO2 is of both scientific and practical interest. In this work we use many-body perturbation theory techniques to investigate two typical n-type dopants, niobium and hydrogen, in TiO2 rutile. Using the GW approximation to determine band edges and defect energy levels, and the Bethe-Salpeter equation for the calculation of the absorption spectra, we find that the defect energy levels form nondispersive bands lying similar to 2.2 eV above the top of the corresponding valence bands (similar to 0.9 eV below the conduction bands of the pristine material). The defect states are also responsible for the appearance of low-energy absorption peaks that enhance the solar spectrum absorption of rutile. The spatial distributions of the excitonic wave functions associated with these low-energy excitations are very different for the two dopants, suggesting a larger mobility of photoexcited electrons in Nb-TiO2.