Ultrasmall HgTe Quantum Dots with Near Unity Photoluminescent Quantum Yields in the Near and Shortwave Infrared

The near and short-wave infrared spectral window (700-1000 and 1000-2000 nms respectively) enables remarkable penetrative imaging and sensing applications. However there are few highly emissive chromophores in this spectral window. Of the available optically active materials in the infrared, mercury chalcogenide nanocrystals are promising candidates for infrared optoelectronic applications due to their narrow bulk bandgaps, spectral tunability and solution processability. Here 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 nanocrystals 1.7 to 2.3 nm diameter, 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. The QDs have a short lifetime of 7 ns and retain their high quantum yields (~60%) in the solid state, allowing for first of their kind photoluminescence imaging and blinking studies of HgTe QDs. Future work will focus on expanding the spectral tunability of the synthesis further into the infrared and optimizing water solubility of the HgTe QDs for in-vivo imaging.