Stimuli-Responsive Biodegradable Cholesteric Films with Color-Tunable Circularly Polarized Ultralong Room-Temperature Phosphorescence

Circularly polarized luminescence (CPL) has been extensively explored in asymmetric catalysis, chiroptical sensing, and next-generation optoelectronics. Herein, we develop a cellulose-based cholesteric photonic platform incorporating chiral phosphors into hydroxypropyl cellulose (HPC) and cellulose nanocrystal (CNC) matrices, two cellulose-derived biopolymers capable of forming helicoidal liquid-crystalline phases. Through evaporation-induced self-assembly, R/S-phosphors are embedded within the HPC/CNC cholesteric matrices, suppressing non-radiative decay while promoting triplet stabilization and circular polarization amplification through host-guest interactions and cholesteric photonic modulation. Consequently, the CPRTP films exhibit exceptional |glum| values reaching 0.51 and ultralong phosphorescence lifetimes of up to 2.4 s, alongside irradiation-time-dependent and humidity-responsive behavior. These large-area, flexible, and biodegradable films enable multicolor chiral phosphorescent patterning and 3D printing, while their renewable/recyclable nature, high glum, and stimuli-responsiveness offer significant potential for information encryption, anti-counterfeiting, and environmental monitoring.