Colloidally prepared CdHgTe and HgTe quantum dots with strong near-infrared luminescence

Several series of CdHgTe composite nanocrystals were prepared using thiol-c apped CdTe nanocrystal precursors to which subsequent layers of HgTe and Cd Te were added. The position of the 'excitonic' photoluminescence peak measu red at room temperature was red-shifted to the near infrared to give emissi on wavelengths ranging from 800 to 1100 nm depending on the quantum dot com position. with quantum efficiency (QE) significantly increased over the pur e CdTe material (QE up to around 40%). Thiol-capped HgTe nanocrystals synth esized in aqueous solution show a broad photoluminescence with a QE of simi lar to 50%. It has been shown using D2O as a solvent that by varying the sy nthesis conditions it is possible to tune the luminescence of HgTe quantum dots to the desired wavelength in the range of 900-2000 nm. HgTe nanocrysta ls passivated at the surface with a thick CdS layer have been shown to be m uch more robust towards heating and "aging" of the optical properties.