Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering , Chinese Academy of Sciences , Ningbo 315201 , People's Republic of China.
Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China.
Inorg Chem. 2019 Feb 4;58(3):2089-2098. doi: 10.1021/acs.inorgchem.8b03178. Epub 2019 Jan 15.
The nanocrystal-in-glass (nanocrystals embedded amorphous matrix) tungsten oxide (WO) thin films with a nanoporous characteristic were prepared via an electron beam evaporation technique. The e-beam evaporated WO thin films present a fast colored/bleached time of 16/11, 16/14, and 12/12 s, a large optical modulation of 92, 91, and 87% at 633 nm, and a high coloration efficiency of 61.78, 62.04, and 67.59 cm C in Li, Na, and Al electrolytes, respectively. On one hand, the improved electrochromic performance is mainly attributed to the short diffusion distance and buffering effect in the host matrix, which facilitates the ion insertion/extraction and alleviates the structural collapse of the framework. On the other, owing to the strong electrostatic interactions between the trivalent cations and the host, the WO thin films in Al possess a shallow diffusion depth and long cycle life. The individual contribution from the capacitance- or diffusion-controlled process is comprehensively demonstrated. Pseudocapacitive behavior in the nanocrystal-in-glass WO thin films is in favor of fast kinetics response and sound cycling stability. Our work offers an in-depth insight of the electrochromic mechanism for nanocrystal-in-glass WO thin films in various electrolytes and sheds light on the fundamental principle in the electrochromic devices.
采用电子束蒸发技术制备了具有纳米多孔特征的纳米晶玻璃（嵌入非晶基质的纳米晶体）氧化钨（WO）薄膜。电子束蒸发 WO 薄膜在 633nm 处具有 16/11、16/14 和 12/12s 的快速着色/褪色时间、92、91 和 87%的大光学调制以及 61.78、62.04 和 67.59cmC 的高着色效率，分别在 Li、Na 和 Al 电解质中。一方面，改进的电致变色性能主要归因于主体基质中的短扩散距离和缓冲效应，这有利于离子插入/提取，并减轻了框架的结构坍塌。另一方面，由于三价阳离子与主体之间的强静电相互作用，WO 薄膜在 Al 中具有较浅的扩散深度和较长的循环寿命。全面证明了电容或扩散控制过程的单独贡献。玻璃化 WO 纳米晶薄膜中的赝电容行为有利于快速动力学响应和良好的循环稳定性。我们的工作深入了解了各种电解质中纳米晶玻璃 WO 薄膜的电致变色机制，并阐明了电致变色器件中的基本原理。
