Ultrasmall HgTe quantum dots with high photoluminescent quantum yields in the near and shortwave infrared

We demonstrate a low temperature synthesis of ultrasmall HgTe quantum dots with superlative optical properties in the near and shortwave infrared. The tunable cold-injection synthesis produces 1.7 to 2.3 nm diameter nanocrystals, with photoluminescence maxima ranging from 900-1180 nm. and a full width half max of ~100 nm (~130 meV). The synthesized quantum dots display extraordinarily high photoluminescence quantum yields (PLQY) ranging from 80-95% based on both relative and absolute methods. Furthermore, samples retain their high quantum yields (~60%) in the solid state, allowing for first of their kind photoluminescence imaging and blinking studies of HgTe QDs. The facile synthesis allows for the isolation of small photostable HgTe quantum dots and which can provide valuable insight into the extremes of quantum confinement.