Emerging stimuli-reversible chromic papers: Mechanisms, nanostructures, properties, and applications

To generate an infinite spectrum of vibrant colors, both nature and human can exquisitely manipulate matter and its interactions with light through finely screened materials, optimally designed micro- and nanostructures, and precisely regulated processes. Even in today’s digital world, rewritable paper-based stimuli-responsive chromic materials remain essential to socioeconomic development and the advancement of civilization, leading to the creation of sophisticated optical materials and devices. In this review, we systematically explore various types of stimuli-responsive chromic papers, categorized by their color-changing mechanisms, including thermo-, photo-, hydro-, mechano-, electrochromism, and others such as light emission, structural color, electronic chromism, and coordination chemistry. Our aim is to comprehensively elucidate the relationships among structure, properties, functions, and applications of these color-changing systems across disciplines, demonstrating their diverse applications in dynamic color displays, inkless printing, information encryption, anti-counterfeiting technologies, smart home products, healthcare, and diagnostic systems. Furthermore, we highlight current challenges and future perspectives in the design and fabrication of sustainable rewritable papers. This review is expected to attract significant interest from the advanced materials community, as well as photonic devices, nanotechnology, and engineering, thereby fostering significant breakthroughs in both scientific investigations and commercial applications.