Simultaneous High‐Contrast Time‐Dependent Afterglow Color and High‐Temperature Resistant Materials via Defect‐Mediated Emission Dynamics

ABSTRACT The simultaneous realization of high‐contrast time‐dependent afterglow color (TDAC) and high‐temperature resistance within a single material system remains highly desirable yet challenging. In this study, we achieved both high‐contrast and high‐temperature‐resistant TDAC by confining polycyclic aromatic hydrocarbons (PAHs) within a boric acid matrix through a straightforward heating and annealing strategy. This process yields a rigid matrix with intentionally introduced structural defects. The rigid matrix spatially confines PAH molecules, enhancing their orange/red afterglow intensity and lifetimes. The structural defects act as trap states, generating a blue afterglow with thermoluminescence characteristics. At elevated temperatures, external thermal energy de‐traps electrons from these defects, amplifying the blue afterglow. The released electrons also transfer to PAHs, sustaining their orange/red afterglow at high temperatures. The combination of distinct emission colors, lifetimes, and temperature‐dependent energy transfer pathways results in a high‐contrast TDAC with an emission wavelength shift of 200 nm, maintaining stable afterglow at temperatures up to 120°C. These properties set a new record among state‐of‐the‐art TDAC systems. We further demonstrate the application of these TDAC materials in intelligent encryption. This work advances the design principles of high‐temperature afterglow materials, paving the way for their use in information storage, optical sensing, and advanced anti‐counterfeiting technologies.