Concurrent tunable structural color, luminescence, and afterglow in single ZnS: X@SiO2 spheres via SiO ₂ ‐nanoarmor and calcination decoupling collaborative strategy

Abstract

The integration of structural color, photoluminescence, and afterglow into a single material remains a fundamental challenge due to the conflicting requirements for structural integrity and high‐temperature crystallization. Here, we present a SiO ₂ ‐nanoarmor and calcination decoupling collaborative strategy to create monodisperse wurtzite‐type ZnS: X@SiO ₂ spheres (X = Ag ⁺ , Cu ²⁺ , Mn ²⁺ ) as a unified, single‐particle optical platform. Spatially, a conformal SiO ₂ nanocoating acts as a thermally stable scaffold, preserving perfect spherical morphology during solid‐phase transformation at 1000°C, thereby enabling angle‐independent structural colors across the visible spectrum via Mie resonance. Calcination decoupling was achieved through an alternating O ₂ /N ₂ atmosphere, which removes carbon deposits at low temperature and subsequently drives a complete sphalerite‐to‐wurtzite phase transition with 91% conversion, while preventing oxidation. Programmable doping introduces engineered energy levels, enabling tunable photoluminescence from 490 nm (blue) to 600 nm (orange) and white emission through co‐doping. The fluorescence quantum yield was 12.8%. Notably, Cu‐ and Mn‐doped spheres exhibit green afterglow lasting up to 12.27 s, and their duration was controlled by the content of the wurtzite phase. This intrinsic multifunctionality allows sophisticated multi‐channel optical encryption, where a single pattern sequentially displays distinct information under natural light, UV illumination, and afterglow conditions.