Post-Synthesis Boron Doping of Silicon Quantum Dots via Hydrosilsesquioxane-Capped Thermal Diffusion

Doped silicon quantum dots (SiQDs) with defined dopant distribution, size, and surface chemistry are highly sought-after as a scientific curiosity because their unique properties offer a wide array of potential applications including multi-modal medical imaging and photovoltaic devices. This report describes a diffusion based post-synthesis doping method for incorporating high concentrations of B (2.5 – 5.0 atomic %) into pre-formed 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.