Feng Jifei, Wang Xinyi, Luo Yi, Wang Jinhui, Wang Zhuanpei, Wei Congyuan, Cai Guofa
Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, School of Materials Science and Engineering, Henan University, Kaifeng 475004, P. R. China.
ACS Appl Mater Interfaces. 2024 Jan 10;16(1):1170-1178. doi: 10.1021/acsami.3c16801. Epub 2023 Dec 27.
Metal-organic frameworks (MOFs) exhibit promising electrochromic (EC) performance owing to their porous structure, regular channel, and tunable component characteristics. However, few reports focus on MOF materials with the EC performance of a transparent to brown-black (neutral colored state) change that is more suitable for smart windows. In this work, we proposed a strategy for synthesizing MOF (named Ni-BPY) EC materials and corresponding films fabricated via a low-cost electrostatic spray deposition technique. The obtained film exhibits excellent EC performance with a neutral color change from transparent to brown-black, a large optical modulation of 70% at 430 nm, and a fast response within 10 s. Benefiting from good electrical and chemical stability, the Ni-BPY film can be cycled over 500 times. Notably, the Ni-BPY MOF film also delivers a stepwise-controlled process during the bleached state due to its porous characteristics. In addition, the unique color variation of the Ni-BPY film derives from the redox reaction of the Ni metal node between Ni and Ni, which is verified by the in situ potential-dependent Raman and X-ray photoelectron spectroscopy (XPS) measurement. As a proof of application, the patterned Ni-BPY EC films and devices are additionally constructed to demonstrate their potential application in electronic tags and logo displays.
金属有机框架材料(MOFs)因其多孔结构、规则通道和可调节的成分特性而展现出有前景的电致变色(EC)性能。然而,很少有报道关注具有从透明到棕黑色(中性颜色状态)变化的电致变色性能且更适用于智能窗户的MOF材料。在这项工作中,我们提出了一种合成MOF(命名为Ni-BPY)电致变色材料的策略以及通过低成本静电喷雾沉积技术制备的相应薄膜。所获得的薄膜表现出优异的电致变色性能,具有从透明到棕黑色的中性颜色变化、在430nm处70%的大光学调制以及在10秒内的快速响应。得益于良好的电学和化学稳定性,Ni-BPY薄膜可以循环超过500次。值得注意的是,由于其多孔特性,Ni-BPY MOF薄膜在漂白状态下还呈现出逐步控制的过程。此外,Ni-BPY薄膜独特的颜色变化源于Ni金属节点在Ni⁰和Ni²⁺之间的氧化还原反应,这通过原位电位依赖拉曼光谱和X射线光电子能谱(XPS)测量得到了验证。作为应用实例,还额外构建了图案化的Ni-BPY电致变色薄膜和器件,以展示它们在电子标签和标志显示中的潜在应用。