Anomalous Dependence of Photocarrier Recombination Time on the Polaron Density of TiO2(110).
Anomalous Dependence of Photocarrier Recombination Time on the Polaron Density of TiO2(110).
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DOI：
10.1021/acs.jpclett.3c01685
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
Huimin Wang;Huixia Fu;Peiwei You;Cui Zhang;Ying Jiang;S. Meng
中科院分区：
文献类型：
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作者：
Huimin Wang;Huixia Fu;Peiwei You;Cui Zhang;Ying Jiang;S. Meng
极化子在能量转换中起着至关重要的作用，但由于它们易受局部原子结构的影响，因此其微观机制仍不清楚。在这里，我们采用从头算非绝热动力学模拟，研究了电子-空穴（e-h）的非辐射复合在金红石型TiO 2（110）表面与不同数量的氧空位（Vo）。与无缺陷表面相比，孤立的Vo通过形成极化子促进电子-氢复合。然而，聚集的Vo形成簇通过增强声子激发诱导极化子扩散的数量级加速，这阻止了缺陷介导的复合，从而延长了光载流子寿命。我们发现，由于极化子的形成，光电子被驱动向顶面迁移。我们的结果表明，缺陷和极化子的多体效应决定的整体复合率，这已被忽略的肖克利-里德-霍尔模型。这些发现解释了有争议的实验观察结果，并表明工程Vo聚集反而会提高极化材料的极化效率。
Polarons play a crucial role in energy conversion, but the microscopic mechanism remains unclear since they are susceptible to local atomic structures. Here, by employing ab initio nonadiabatic dynamic simulations, we investigate electron-hole (e-h) nonradiative recombination at the rutile TiO2(110) surface with varied amounts of oxygen vacancies (Vo). The isolated Vo facilitates e-h recombination through forming polarons compared to that in the defect-free surface. However, aggregated Vo forming clusters induce an order-of-magnitude acceleration of polaron diffusion by enhancing phonon excitations, which blocks the defect-mediated recombination and thus prolongs the photocarrier lifetime. We find that photoelectrons are driven to migrate toward the top surface due to polaron formation. Our results show the many-body effects of defects and polaron effects on determining the overall recombination rate, which has been ignored in the Shockley-Read-Hall model. The findings explain the controversial experimental observations and suggest that engineering Vo aggregation would instead improve photocatalysis efficiencies in polaronic materials.