Patternable Siloxane-Functionalized Carbon Dots for Solid-State Luminescent Microstructures and Optical Security

Silane- or siloxane-functionalized carbon dots (SiCDs), a unique subclass of carbon nanomaterials modified with silane or siloxane groups, offer solid-state luminescence, solution processability, and chemical reactivity, making them promising candidates for optical coatings, displays, and security technologies. However, the precise patterning of carbon dot materials remains underdeveloped, limiting their integration into advanced photonic and anticounterfeiting systems. In this work, we present a scalable thermal nanoimprinting strategy to fabricate high-resolution, luminescent micro- and nanostructures using SiCDs as both emissive materials and imprintable resists. The SiCDs are synthesized via a solvothermal method using citric acid and urea as carbon sources and 3-glycidyloxypropyltrimethoxysilane (GPTMS) as a siloxane-functionalizing agent. By varying the feed ratio of citric acid to GPTMS, the carbon core and surface fluorophore of SiCDs can be effectively tailored, enabling enhancement of their solid-state photoluminescence quantum yield, optical transmittance, and gelation temperature. Using SiCDs as the imprint resist, microstructures, including micropillars and gratings with feature sizes ranging from 2 to 50 μm, are fabricated by thermal nanoimprinting. The resulting patterns exhibited excellent fidelity, surface properties, and thermal stability. Furthermore, a dual-mode anticounterfeiting surface is constructed by combining nanoimprinting with screen printing, enabling dynamic angle-dependent holography and UV-excited fluorescence within a single patterned film. This study highlights the potential of SiCDs as a multifunctional material platform for solid-state luminescent patterning and positions carbon dot patterning as a rising frontier in nanophotonics and optical security.