Size quantization effect in highly stable UV emitting HgTe nanoparticles: Structure and optical properties

Abstract

We report a simple one pot aqueous chemical synthesis route to fabricate very small and highly stable HgTe nanoparticles (NPs) capped with L-cysteine ethyl ester hydrochloride (LEEH). The LEEH concentration has found to be critical for desired size NP synthesis. Structural analyses by grazing angle x-ray diffraction and high resolution electron microscopy studies indicate HgTe NPs to exhibit a fcc phase with ⟨111⟩ prominent reflection having monodispersed NP size of around 2.0 nm. A strong size quantization effect marked by a prominent excitonic absorption at 4.436 eV blueshifted by 4.586 eV from the bulk band gap value has been observed in their optical absorption studies. A strong and narrow Gaussian fluorescence emission at 3.3 eV has been observed for 2.0 nm NP size whose width is being narrowed down with increasing LEEH concentration. The strong UV range absorption and emission have been observed for the first time in HgTe NPs.