Transparent Carbon Dots‐in‐Glass Composite With UV Emission Fabricated via “In Situ” Generation

Carbon dots (CDs) are promising metal‐free fluorescent nanomaterials, yet their solid‐state application is hindered by aggregation‐caused quenching. Inorganic glasses offer an ideal host matrix for UV‐emitting CDs due to their high transparency and robust stability. However, the poor thermal stability of organic CDs precursors is fundamentally incompatible with the high‐temperature requirements of conventional glass processing. Inspired by nanocrystal‐in‐glass composites, in this paper, we develop an in situ strategy to fabricate CDs‐in‐glass composites via a low‐temperature solution‐combustion technique. This method enables concurrent glass and CDs formation via a self‐sustaining reaction that overcomes thermal incompatibility, with the aqueous medium ensuring homogeneous dispersion. The resulting composite exhibits high transparency and excitation‐dependent multicolor emission, with an optimal UV emission at 360 nm. Compared to the CDs without glass encapsulation, the embedded CDs in glass exhibit reduced particle size, thus exhibiting blue‐shifted emission, indicating strong spatial confinement by the glass matrix. Mechanistic studies reveal that highly mobile K + ions not only promote the fluorescence of CDs by forming surface states but also bridge them into the glass network via chemical bonding, ensuring stable encapsulation. As a result, the composite demonstrates remarkable thermal and pH stability, highlighting the superior preservation capability of the glass host for the CDs' optical properties.