Slot-Die-Coated Photochromic Naphthopyran-Based Films for UV-B Light Detection

Photochromic materials have attracted widespread interest for an innate ability to change color in response to UV-B light without electronic integration. Major challenges toward the realization of sensors based on these materials are the lack of color change reversibility and chemical stability of the photochromic dyes. Here, we demonstrate the use of slot-die coating to develop flexible plastic and textile integrated films capable of color changes under UV-B light exposure. The films change from near colorless to amber orange with UV-B exposure and revert to near colorless when heated at 100 °C. The films show a stronger response to UV-B light (compared to longer wavelength light) and exhibit in-lab ambient condition stability. This work has potential relevance for materials science and health care applications and contributes to the development of non-electronic UV light-sensing materials.