Synthesis of stable near-infrared emitting HgTe/CdS core/shell nanocrystals using dihydrolipoic acid as stabilizer

Abstract

HgTe/CdS core/shell nanocrystals (NCs) with highly-stable near-infrared (NIR) emissions were synthesized by employing dihydrolipoic acid (DHLA) as a stabilizer. This synthetic route was performed using Te powder as the tellurium source to prepare HgTe NCs, and H2S generated by the reaction of Na2S–H2SO4 as the sulfur source for synthesizing HgTe/CdS core/shell NCs at room temperature. The fluorescence emission peaks of DHLA-capped HgTe/CdS NCs could be facilely tuned from 910 nm to 1200 nm by varying the reflux time at 100 °C, with a maximum photoluminescence quantum yield of 52%. The obtained HgTe/CdS NCs exhibited an NIR stable emission when heated at 75 °C. Correspondingly, these HgTe/CdS core/shell NCs displayed excellent colloidal dispersion stability and long exciton lifetimes that reached up to 47.6 ns in an aqueous medium. The resultant HgTe/CdSe NCs have been successfully used to fabricate NIR emitting thin films on the surface of polymers and to perform fluorescence imaging in a live animal.