Smart textiles demonstrating optical responses to external light stimuli hold great promise as functional materials with a wide range of applications in personalized decoration and information visualization. The incorporation of high-contrast, vivid, and real-time optical signals, such as color change or fluorescence emission, to indicate light on/off states is both crucial and challenging. In this study, we have developed a dual output photosensitive dye system possessing photochromic and photofluorescent properties, which was successfully applied to the dyeing and finishing processes of cotton fabrics. The design and fabrication of this dye system were based on the unique photoinduced proton transfer (PPT) principle exhibited by the water-soluble spiropyran (trans-MCH) molecule. The dual output response relies on the open-/closed-loop mechanism, wherein light regulates the trans-MCH molecule. Upon excitation by UV or visible light, the dye system and dyed fabrics display significant color changes and fluorescence switching in a real-time and highly reversible manner. Moreover, diverse photosensitive color systems can be tailored by direct blending with commercially available water-soluble dyes. By integrating high-contrast dual optical outputs into this scalable, versatile, and reversible dye system, we envisage the development and design of smart textiles capable of producing high-end products.
Keywords: photoacid; photoinduced proton transfer; spiropyran; textiles; visible-light response.