Hao Tingting, Zhang Leipeng, Ji Haoyu, Zhou Qiyu, Feng Ting, Song Shanshan, Wang Bo, Liu Dongqi, Ren Zichen, Liu Wenchao, Zhang Yike, Sun Jiawu, Li Yao
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Center for Composite Materials and Structure, Harbin Institute of Technology, Harbin 150001, China.
Polymers (Basel). 2023 Jun 10;15(12):2640. doi: 10.3390/polym15122640.
The application of flexible indium tin oxide (ITO-free) electrochromic devices has steadily attracted widespread attention in wearable devices. Recently, silver nanowire/poly(dimethylsiloxane) (AgNW/PDMS)-based stretchable conductive films have raised great interest as ITO-free substrate for flexible electrochromic devices. However, it is still difficult to achieve high transparency with low resistance due to the weak binding force between AgNW and PDMS with low surface energy because of the possibility of detaching and sliding occurring at the interface. Herein, we propose a method to pattern the pre-cured PDMS (PT-PDMS) by stainless steel film as a template through constructed micron grooves and embedded structure, to prepare a stretchable AgNW/PT-PDMS electrode with high transparency and high conductivity. The stretchable AgNW/PT-PDMS electrode can be stretched (5000 cycles), twisted, and surface friction (3M tape for 500 cycles) without significant loss of conductivity (ΔR/R ≈ 16% and 27%). In addition, with the increase of stretch (stretching to 10-80%), the AgNW/PT-PDMS electrode transmittance increased, and the conductivity increased at first and then decreased. It is possible that the AgNWs in the micron grooves are spread during PDMS stretching, resulting in a larger spreading area and higher transmittance of the AgNWs film; at the same time, the nanowires between the grooves come into contact, thus increasing conductivity. An electrochromic electrode constructed with the stretchable AgNW/PT-PDMS exhibited excellent electrochromic behavior (transmittance contrast from ~61% to ~57%) even after 10,000 bending cycles or 500 stretching cycles, indicating high stability and mechanical robustness. Notably, this method of preparing transparent stretch electrodes based on patterned PDMS provides a promising solution for developing electronic devices with unique structures and high performance.
柔性氧化铟锡（无ITO）电致变色器件在可穿戴设备中的应用一直备受广泛关注。最近，基于银纳米线/聚二甲基硅氧烷（AgNW/PDMS）的可拉伸导电薄膜作为用于柔性电致变色器件的无ITO衬底引起了极大兴趣。然而，由于AgNW与低表面能的PDMS之间的结合力较弱，在界面处可能发生分离和滑动，因此仍难以实现高透明度和低电阻。在此，我们提出一种方法，通过不锈钢膜作为模板，通过构建微米级凹槽和嵌入结构对预固化的PDMS（PT-PDMS）进行图案化，以制备具有高透明度和高导电性的可拉伸AgNW/PT-PDMS电极。可拉伸的AgNW/PT-PDMS电极可以拉伸（5000次循环）、扭曲和进行表面摩擦（用3M胶带摩擦500次循环），而不会导致导电性显著损失（ΔR/R≈16%和27%）。此外，随着拉伸程度的增加（拉伸至10%-80%），AgNW/PT-PDMS电极的透光率增加，导电性先增加后降低。有可能在PDMS拉伸过程中，微米级凹槽中的AgNW会展开，导致AgNW薄膜的展开面积更大、透光率更高；同时，凹槽之间的纳米线相互接触，从而提高了导电性。用可拉伸的AgNW/PT-PDMS构建的电致变色电极即使在10000次弯曲循环或500次拉伸循环后仍表现出优异的电致变色行为（透光率对比度从61%到57%），表明其具有高稳定性和机械鲁棒性。值得注意的是，这种基于图案化PDMS制备透明拉伸电极的方法为开发具有独特结构和高性能的电子器件提供了一种有前景的解决方案。
