Boron Doping of Silicon Quantum Dots via Hydrogen Silsesquioxane-Capped Diffusion for Photovoltaics and Medical Imaging

Doped silicon quantum dots (SiQDs) with defined size, dopant distribution, and surface chemistry are highly sought after as a scientific curiosity because their unique properties offer a wide array of potential applications including multimodal medical imaging and photovoltaic devices. This report describes a diffusion-based postsynthesis doping method for incorporating high concentrations of B (2.5–5.0 at. %) into preformed SiQDs of predefined sizes while simultaneously maintaining their structure and morphology. The processing temperature, atmosphere, and QD size all strongly influence the resulting B-doped SiQDs. The as-synthesized doped SiQDs exhibit size-dependent photoluminescence spanning the visible to near-infrared spectral regions, are compatible with aqueous environments, and are readily rendered compatible with organic solvents upon functionalization with appropriate alkoxide surface groups. Being able to effectively tune the size and surface chemistry of the present B-doped SiQDs make them excellent candidates for use in targeted applications such as multimodal imaging and photovoltaic devices.