Preparation and Photoluminescence of Hybrid SiO_2-Coated CdTe Nanocrystals

摘要

Novel hybrid SiO_2-coated CdTe core-shell nanocrystals (NCs) were fabricated by re-dispersing green-emitting CdTe NCs in a solution of Cd~(2+) ions, thioglycolic acid (TGA), tetraethyl orthosilicate and ammonia with a sol-gel reaction at room temperature and a further reflux procedure. The hybrid NCs consisted of a CdTe core and a hybrid SiO_2 shell with CdS-like clusters. The clusters created by the reaction of Cd~(2+) and S~(2-) generated by the decomposition of TGA during reflux. The hybrid NCs exhibited tunable photoluminescence (PL) color from green to red and high PL quantum yield (PLQY). The CdS-like clusters play an important role for the hybrid NCs with numerous PL properties. Compared with initial CdTe NCs, the PLQY of the hybrid NCs increased from 18% to 47% together with a red-shifted PL peak wavelength of 61 nm. The average lifetime of the hybrid NCs (39 ns) is longer than that of initial CdTe NCs (25 ns). The high PLQY and the hybrid shell make CdTe NCs an important application for biological technique.