Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.
Nanoscale. 2018 Jul 13;10(27):12981-12990. doi: 10.1039/c8nr01648h.
A solution processed metal nanowire network is a promising flexible transparent electrode to replace brittle metal oxides for printable optoelectronics applications, but suffers from the issue of pseudo contact between nanowires. Herein, using volatile solvent mists as a powerful "zipper", we demonstrate a simple and rapid method to effectively weld silver nanowires, which dramatically improves the conductivity and robustness of the silver nanowire network based flexible transparent electrodes. We reveal that for a stacked network structure, the unique wedge-shaped nanogaps between the long nanowires and substrate provide a strong capillary force during solvent evaporation, which is much larger than that between zero-dimensional nanoparticles and gives a decisive contribution for nanowire junction welding, and this nanowire-substrate interplay force is positively related to the wettability of the substrate. At the same time, the dissolution-reprecipitation of the capping agent on the silver nanowire surface as the natural adhesive can fix the network on the substrate tightly, which enhances the robustness of the network. Our approach solves two key issues in solution-processed transparent electrodes in one simple step, and is compatible with various mild solution-processed optoelectronic devices, especially those containing heat-sensitive or chemical-sensitive materials. Moreover, a new type of invisible infrared encryption display is demonstrated based on this approach.
溶液加工金属纳米线网络是一种很有前途的柔性透明电极，有望替代易碎的金属氧化物，用于可印刷光电应用，但存在纳米线之间假性接触的问题。在此，我们使用易挥发溶剂雾作为强大的“拉链”，展示了一种简单而快速的方法来有效地焊接银纳米线，这极大地提高了基于银纳米线网络的柔性透明电极的导电性和稳定性。我们揭示了对于堆叠的网络结构，长纳米线和基底之间独特的楔形纳米间隙在溶剂蒸发过程中提供了强大的毛细力，其远大于零维纳米颗粒之间的力，并且为纳米线连接焊接提供了决定性的贡献，并且这种纳米线-基底相互作用力与基底的润湿性呈正相关。同时，银纳米线表面的盖帽剂的溶解-再沉淀作为天然粘合剂可以将网络牢固地固定在基底上，从而增强了网络的稳定性。我们的方法在一个简单的步骤中解决了溶液处理透明电极中的两个关键问题，并且与各种温和的溶液处理光电设备兼容，特别是那些含有热敏或化学敏材料的设备。此外，还基于此方法展示了一种新型隐形红外加密显示。
