Structural Coloration and Up/Down‐Conversion Photoluminescence of Carbon Nanotube Fibers for Ultraviolet Detection

Abstract Carbon nanotubes (CNTs) are in great demand in many fields because of their unique properties such as high conductivity, chemical stability, lightweight, and high strength. They also received much attention in optical‐related fields because of the super‐black characteristics under visible light and the photothermal effect of infrared light. Recently, the coloration of CNTs under visible light is realized by a simple liquid phase method with the help of silica photonic crystal (PC) coatings. However, the response modulation such as the photoluminescence (PL) property of CNTs to the infrared and ultraviolet (UV) bands is not yet studied. Herein, silane functionalized carbon dots (SiCDs) are introduced into silica PCs, and successfully realized the structural coloration and PL of CNT fibers (CNTFs). The optical and fluorescence visualization of single CNTs and suspended CNT networks (SCNTNs) is also realized with the assistance of SiCDs droplets. These SiCDs‐decorated SiPCs‐coated CNTFs (SiCDs@SiPCs‐CNTFs) exhibit an up/down‐conversion PL response, and the excitation light source can be UV light, visible light, and near‐infrared laser. The structural coloration and the development of new PL properties will promote the wide applications of PL carbon hybrid materials in many fields such as smart displays, intelligent textiles, anti‐counterfeiting, etc.