Correlation of growth, structure, optical and electronic properties of novel Nb3O7(OH) and Nb2O5 nanostructures

一维单晶纳米结构金属氧化物电极具有为载流子创造高效通道的优势。然而，在这些结构中出现的缺陷和不同的晶体修饰会影响它们在诸如杂化和染料敏化太阳能电池、电池或（光）催化等应用中的性能。本项目将重点研究新型Nb3O7（OH）和Nb2O5纳米结构，并将其与已有的TiO2进行比较。虽然氧化铌系统具有很高的应用潜力，但很少对其进行详细阐述。接下来是详细的分析，重点将放在控制生长和生长条件对氧化铌系统特性的影响。对于金属氧化物纳米结构来说，理解和控制载流子迁移率是必要的，以便在器件中进行定制应用。在这方面，本项目侧重于分析晶界和结晶度对电荷输运和重组的影响，因为这些过程是由结构缺陷引起的，可能会主导光学和电子性能。通过改变生长条件，更好地理解导致这些缺陷的机制将允许控制和限制缺陷的形成，正如我们之前对TiO2所展示的那样。高分辨率透射显微镜研究与光学和电子表征方法的结合，使我们对晶体生长、结构、电荷输运等物理现象以及这些性质之间的关系有了基本的了解。

One-dimensional single crystalline nanostructured metal oxide electrodes have the advantage of creating efficient pathways for charge carriers. However, defects occurring in these structures and different crystallographic modifications affect their performance in applications such as hybrid and dye-sensitized solar cells, batteries or (photo-)catalysis. This project will focus on novel Nb3O7(OH) and Nb2O5 nanostructures and compare them with the well-established TiO2. The niobium oxide systems have rarely been elaborated, even though they have a high potential for applications. Next to a detailed analysis, special focus will be put on the controlled growth and the influence of the growth conditions on the characteristics of the niobium oxide systems. For the metal oxide nanostructures it will be essential to understand and control the charge carrier mobility in order to allow tailored application in devices. In this regard, this project focusses on the analysis of the effects of grain boundaries and the crystallinity on charge transport and recombination as these processes caused by structural defects might dominate the optical and electronic properties. By varying the growth conditions, better understanding of the mechanisms leading to such defects will allow to control and limit the formation of defects as it has been shown previously by us for TiO2. The combination of high-resolution transmission microscopy studies and optical and electronic characterization methods enables us to obtain a fundamental understanding of the physical phenomena of crystal growth, structure, charge transport, etc. and the correlation between these properties.