表面缺陷决定的单晶二氧化钛纳米线阵列电极的电子传输性能及其提高

Charge transport within electrode materials plays a major role in determining the optoelectronic device performance. Ordered single-crystal TiO2 nanowire arrays which offer an ideal electron transport path are expected to have fast electron mobility, and have received substantial attention in various optoelectronic devices. However, measurements have shown that their electron mobility is not superior to that in random nanoparticle films. Surface defect is one of the key factors limiting the electron transport. In this project, we will study the surface defects (including oxygen vacancy and titanium interstitial) that limit the charge transport in ordered single-crystal rutile TiO2 nanowire arrays. Furthermore, we will do surface treatment on the TiO2 nanowire arrays in order to remove surface defects or reduce their density, and improve their charge transport property. By using spectroscopies like X-ray photoelectron spectroscopy, photoluminescence, oxygen vacancy and titanium interstitial defects will be characterized separated; by using transient photoelectric technology, the impact of density and energy level distribution of defects on the charge transport will be studied; surface treating approaches like etching will be tried in order to remove the surface defect layer and improve the charge transport of nanowires. This project will enable the structure-activity relationship between ordered single crystal one dimensional nanostructure and fast charge transport be reflected, which is significant in promoting the wide range application of ordered single crystal nanowire arrays and improving the corresponding device performance.

电极材料的电子传输性能往往是决定光电转换器件性能的关键因素。阵列单晶一维二氧化钛纳米结构由于具有直接的电子传输通道，潜在的快速电子传输性能而被应用于各种光电转换器件中。然而研究发现电子在其中的传输并不比在多晶纳米颗粒薄膜中快。表面缺陷是限制电子传输性能的关键因素。本项目针对影响单晶一维二氧化钛纳米线电子传输性能的表面缺陷（氧空位和钛间隙）进行研究，并在此基础上对纳米线进行表面处理，消除表面缺陷或降低缺陷密度，提高其电子传输性能。项目将通过利用X射线光电子能谱、荧光光谱等测试手段对氧空位和钛间隙分别进行表征；结合瞬态光电测试技术探究缺陷密度以及缺陷能级分布对电子传输的影响；采用腐蚀法去除表面缺陷层等思路对一维纳米线进行处理，提高电子传输性能。本项目的研究结果将使阵列单晶一维纳米结构同电子传输性能之间的构-效关系得到体现，有助于促进阵列单晶一维纳米结构材料的广泛应用及相应器件性能的提高。

半导体纳米光电极的结构设计和构筑对高效光电化学器件的开发有重要意义。光电极材料的电荷传输性能往往是决定其电荷收集效率以及光电性能的关键因素。本项目选择纳米二氧化钛为模型研究材料，研究了光电极的微观结构，特别是表面缺陷以及电荷在其中的传输动力学行为。探讨了光电极微观结构与电荷传输性能之间的构-效关系。通过采用强度调制光电流，光电压谱，以及荧光光谱等表征技术，首次阐明了影响单晶阵列一维金红石纳米线电荷行为的表面缺陷类型，能级分布，进一步提出了一种简单且有效降低表面缺陷密度的湿化学法，大幅提高了单晶一维金红石二氧化钛纳米阵列光电极的电荷传输性能。此外，在本项目研究的基础上，我们还设计、构筑了几种新颖的光电极结构，经过表面缺陷消除处理，发现它们均具有良好的电荷传输性能。这些研究成果对未来光电化学器件的发展将起到很大的推动作用。我们应邀在Adv. Mater.杂志上撰写了一篇综述论文，总结了我们在半导体光电极的设计及电荷传输研究方面的研究工作。在该项目的支持下，共发表和接收SCI论文9篇，其中包括Adv. Mater.，Chem. Sci.，J. Am. Chem. Soc.等具有国际影响力的高水平杂志。