Synergistic dynamic pitch and incoherent scattering enabling programmable cellulose thermochromic hybrids with UV–Vis-NIR broad modulation and multifunctionality

Hydroxypropyl cellulose (HPC) forms semi-transparent cholesteric liquid crystals (CLCs) under lyotropic conditions, exhibiting concentration- and temperature-dependent structural colors, covering the spectral region from ultraviolet (UV) to near-infrared (NIR). Notably, HPC CLCs exhibit a milky-white color against a white background owing to the incoherent scattering. Inspired by basal melanin-mediated color saturation between blue and white Steller's jay feathers, black backgrounds significantly enhance the saturation of structural colors by suppressing multiple incoherent scattering. Leveraging this mechanism, we propose a facile three-dimensional (3D) integration method for fabricating thermoresponsive and extreme-condition-resistance devices, composed of HPC CLCs with structural colors and thermochromic powders (TCPs) with a color switch between black and white. A single device displays color transitions among black, blue, green, red, and white, resulting from the synergistic effects of helical pitch modulation and dynamic incoherent scattering upon temperature stimuli. Intriguingly, coupling conductive carbon-oil substrates with hybrids enables electrothermal multicolor displays through Joule heating effects. Furthermore, the devised hybrids show great potential in anti-counterfeiting, smart labeling, camouflage, and information encryption through programmable TCP patterning beneath HPC CLCs. This work pioneers a new paradigm for synergistic integration of stimuli-responsive photonic crystals with adaptive absorbers, enabling scalable fabrication of color-switchable devices with customized control capabilities.