Highly fluorescent water soluble CdxZn1−xTe alloyed quantum dots prepared in aqueous solution: one-step synthesis and the alloy effect of Zn

Abstract

A novel water-soluble Cd_xZn_1−xTe alloyed quantum dot (QD) with glutathione (GSH) as the stabilizer was prepared for the first time through a one-step aqueous route. Due to the positive alloy effect of Zn in CdTe, the as-prepared Cd_xZn_1−xTe alloyed QDs possess broadened band gap, hardened lattice structure and lower defect densities. Accordingly, the size and composition-dependent fluorescent emission wavelength of the resultant Cd_xZn_1−xTe alloyed QDs can be tuned from 470 to 610 nm, and their photoluminescent quantum yield (PL QY) can reach up to 75%. Especially in the wavelength range of 500–590 nm, the overall PL QYs of the as-prepared Cd_xZn_1−xTe QDs were above 50%, which indicates their great predominance in bio-applications. Moreover, a simple tool for quick and ultrasensitive Pb²⁺ and Hg²⁺ detection was produced by measuring the relatively PL intensity of GSH-capped Cd_xZn_1−xTe alloyed QDs with a common fluorophotometer, which also shows their promising application on heavy metal ion detection.