Synthesis and optical properties of water-soluble CdTe1-xSex quantum dots with ultra-long fluorescence lifetime

Water-soluble ternary-alloyed CdTe1-xSex quantum dots (QDs) have been synthesized via a simple one pot approach in aqueous phase. The as-prepared CdTe1-xSex QDs show good crystallinity, excellent monodispersity, and a narrow size distribution with average size of 3.0 nm. Lattice parameters and band gaps of the ternary-alloyed CdTe1-xSex (0 <= x < 1) QDs are regulated respectively in linear and quadratic relationships with the Se content (x). By tuning composition, the photoluminescence (PL) emission wavelength of CdTe1-xSex can cover from 528.9 to 689.3 nm, and gradually moved to longer wavelengths with a decrease content of Se (x). The lifetime of CdTe1-xSex QDs is decreased gradually with the Se content (x) augment, attributing to the decreasing lattice spacing resulting from substitution of the larger Te atoms with the smaller Se atoms, bringing about a incremental plasmonic coupling effect at smaller inter-lattice fluorophore distance. However, the as-prepared CdTe1-xSex QDs (0 <= x < 1) have significantly longer fluorescence lifetimes of >80 ns with the maximum lifetime up to 174.64 ns. The longer life is good for the application of photoelectric conversion, fluorescent biomedical imaging and detecting. (C) 2016 Elsevier B.V. All rights reserved.