Pseudomorphic Synthesis of Monodisperse Afterglow Carbon Dot‐Doped SiO2 Microparticles for Photonic Crystals

Abstract Synthesizing monodisperse afterglow microparticles (MPs) is crucial for creating photonic crystal (PC) platforms with multiple optical states for optoelectronics. However, achieving high uniformity in both size and morphology is challenging for inorganic afterglow MPs using conventional methods. In this contribution, a novel approach for the synthesis of carbon dot (CD)‐doped SiO 2 MPs with tunable afterglow properties and size distributions is reported. These mechanism studies suggest that the pseudomorphic transformation of SiO 2 MPs enables CD doping, providing a hydrogen bond‐enriched environment for triplet state stabilization, which generates green afterglow while retaining the uniformity in size and morphology of the parent SiO 2 MPs. Furthermore, the utility of CD‐doped SiO 2 MPs in the fabrication of rationally designed PC patterns is shown using a combined consecutive dip‐coating and laser‐assisted etching strategy. The pattern displays multiple optical responses under different lighting conditions, including angle‐dependent structural colors and blue luminescence under daylight and upon 365‐nm irradiation, respectively, as well as time‐dependent green afterglow after ceasing UV excitation. The findings pave the way for further controlling the dynamics of spontaneous emissions by PCs to enable complicated optical states for advanced photonics.