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Luminescent colloidal silicon quantum dots (SiQDs) have been explored as alternatives to metal-based QDs for light-emitting diodes (LEDs) because of the abundance and biocompatibility of silicon. To date, the broad electroluminescence (EL) bandwidth (> 100 nm) and blue-shifting of EL at high applied voltages of SiQD-LEDs have been outstanding challenges that limited competitive spectral purity and device stability. Herein, we report the fabrication and testing of SiQD-LEDs that incorporate a Fabry-Pérot cavity that exhibit a narrow spectral linewidth as low as ca. 23 nm. The presented devices also provide spectral and visual stability from +4 V to +8 V, as well as spectral tunability.

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.