Scalable and Bright: Unlocking Functional Silicon Quantum Dots with Near-Unity Internal Quantum Yield through Universal Plasma-Driven Engineering †

Abstract

Silicon quantum dots (SiQDs) are a promising class of functional nanomaterials combining non toxicity, in comparison with their binary counterparts, with tunable optoelectronic properties. How ever, reaching their full potential in applications requires scalable fabrication and fast and simpler modification method, enabling bonding of a broad variety of ligands and control over the photo luminescence efficiency. Here, we advance a versatile synthesis–modification methodology based on non-thermal plasma. In particular, we complement synthesis in non-thermal plasma allowing for extensive size tuning of SiQDs with unconventional air-free plasma-induced in-liquid reactions (PILR) which enable rapid attachment of diverse ligands, using 3D-printed components for atmo spheric control. Our approach yields brightly luminescent SiQDs from the diameter of 2.4 nm up with quantum yields up to 20% and excellent colloidal stability across solvents of varying polarity. Spectrally resolved lifetime analysis uncovers a near-unity internal quantum yield for bright SiQDs and reveals how surface chemistry and agglomeration govern dark-to-bright QD population ratios and photoluminescence quenching. Additionally, we simplify the well-established protocols of thermal hydrosilylation, showing that controlled-atmosphere sample collection without any further purification steps is the necessary condition for obtaining monodispersions with good optical properties. These results define a simple route to functionally engineered SiQDs, providing new insight into emission dynamics and establishing a strong foundation for their integration into advanced photonic, bioimaging, and energy-harvesting devices.