Zhou Dan, Tong Zhibo, Xie Hongmei, Sun Jiaotong, Chen Fenggui
Chongqing Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology, College of Materials Science and Engineering, Yangtze Normal University, Chongqing 408100, China.
Materials (Basel). 2023 Mar 28;16(7):2681. doi: 10.3390/ma16072681.
To improve the electrochromic (EC) properties of sol-gel-derived WO films, a series of organic small molecules, such as dopamine (DA), catechol, tyramine, phenol and 2-phenylethylamine, were added into peroxotungstic acid precursor sols as structure-directing additives, and five modified WO films were prepared by a simple and low-cost complexation-assisted sol-gel method. The effects of the above additives on the EC properties of the modified WO films have been studied in detail. Compared with the pure WO polycrystalline film, all the modified films combine the advantages of nanocrystalline and amorphous phases and show higher EC properties attributed to the unique nanocrystal-embedded amorphous structure. The results indicate that different additives with different numbers and types of functional groups (hydroxyl and amino groups) can change the microstructure, morphology, and thus electrochemical and EC properties of the films in various degrees. The additives, in order of their strong interactions with the sols, are DA, catechol, tyramine, phenol and 2-phenylethylamine, primarily depending on the number of hydroxyl groups. Of all the additives, DA with both catechol hydroxyl and amino groups shows the most positive effect; that is, the WO film modified with DA exhibits the best EC properties in terms of contrast, switching speed, stability, and coloration efficiency.
为改善溶胶 - 凝胶法制备的WO薄膜的电致变色（EC）性能，将一系列有机小分子，如多巴胺（DA）、邻苯二酚、酪胺、苯酚和2 - 苯乙胺，作为结构导向添加剂添加到过氧钨酸前驱体溶胶中，并通过一种简单且低成本的络合辅助溶胶 - 凝胶法制备了五种改性WO薄膜。详细研究了上述添加剂对改性WO薄膜EC性能的影响。与纯WO多晶薄膜相比，所有改性薄膜兼具纳米晶相和非晶相的优点，并且由于独特的纳米晶嵌入非晶结构而表现出更高的EC性能。结果表明，具有不同数量和类型官能团（羟基和氨基）的不同添加剂能够在不同程度上改变薄膜的微观结构、形貌，进而改变其电化学和EC性能。按照与溶胶相互作用强度的顺序，添加剂依次为DA、邻苯二酚、酪胺、苯酚和2 - 苯乙胺，这主要取决于羟基的数量。在所有添加剂中，同时具有邻苯二酚羟基和氨基的DA表现出最积极的效果；也就是说，用DA改性的WO薄膜在对比度、开关速度、稳定性和着色效率方面表现出最佳的EC性能。
