Wearable fibrous devices, as one of the most important direction in the future, are now in the stage of vigorous development. The developed fibrous lithium ion batteries, solar cells, memories and supercapacitor, due to their fibrous architecture, are easily to integrate into our daily clothes for e-textiles. For that, the carbon nanotube fiber, with characteristics of flexible, lightweight and multistage interface, thus can act as excellent flexible electrodes candidate .

Recently, the Qingwen Li’s research group from Suzhou Institute of Nano-Tech & Nano-Bionics, Chinese Academy of Sciences (SINANO) has made progress in the field of wearable fibrous devices. The flexible carbon nanotube fiber was chosen as anode that to be sequentially coated by a thin layer of compact n-TiO₂, meso-TiO₂, CH3NH3PbI_3-xCl_x, P3HT/SWNT and silver (Ag) nanowire network from the inside out via a solution method, after which another carbon nanotube fiber was twisted to form a double-twisted fibrous architecture, finally, the solar cell was sealed by a transparent polymer layer to increase stability. Our all-solid-state double-twisted fibrous perovskite solar cell exhibits a maximum PCE of 3.03 %, stability longer than 96 hours in ambient condition, and excellent flexibility upon bending for more than 1000 cycles without degradation. This work has been published in the journal Advanced Materials, 2015, 27, 3831-3835), which also be reported by famous international scientific magazine, New Scientist, see Figure 1. Besides, the flexible carbon nanotube fiber, functionalized with a disorder graphene layer, was used to form non-volatile all-carbon memories, which shows ON/OFF ratio up to 10⁹, speed higher than 3 ms and life time larger than 500 cycles in vacuum conditions. This work has been published in the journal Physical Chemistry Chemical Physics，17(11): 7104-7108, see Figure 2.

Based on the fundamental research, the Qingwen Li’s group also joint the effort with Suzhou Creative nano-carbon company to promote the industrializing research of carbon nanotube fibers, and periodic success has been obtained, see Figure 3.

      Figure 1. Wearable double-twisted fibrous perovskite solar cell(Image by LIQing Wen's Group)

Figure 2. All-carbon non-volatile memories from carbon nanotube fibers(Image by LIQing Wen's Group)

Figure 3. Industrializing research of carbon nanotube fibers(Image by LIQing Wen's Group)