Preparation of stable, bright luminescent nanoparticles having compositionally engineered properties
View Patent ↗A method is provided for preparing luminescent semiconductor nanoparticles composed of a first component X, a second component A, and a third component B, wherein X, A, and B are different, by combining B with X and A in an amount such that the molar ratio B:(A+B) is in the range of approximately 0.001 to 0.20 and the molar ratio X:(A+B) is in the range of approximately 0.5:1.0 to 2:1. The characteristics of the thus-prepared nanoparticles can be substantially similar to those of nanoparticles containing only X and B while maintaining many useful properties characteristic of nanoparticles containing only X and A. The nanoparticles so prepared can additionally exhibit emergent properties such as a peak emission energy less than that characteristic of a particle composed of XA or XB alone; this method is particularly applicable to the preparation of stable, bright nanoparticles that emit in the red to infrared regions of the electromagnetic spectrum. Luminescent semiconductor nanoparticles having exemplary properties are also provided.
1. A method for preparing quantum dot nanoparticles that exhibit emission in the red or infrared spectral range which comprises: (i) combining a cadmium precursor, a selenium precursor, and a tellurium precursor in a solvent, wherein the mole ratio of tellurium to selenium is in the range of about 0.01 to about 0.10; (ii) inducing formation of a nanoparticle core using a first accelerant; (iii) combining the nanoparticle core with a solvent, a sulfur precursor, a second accelerant, and a cadmium precursor, a zinc precursor, or both a cadmium precursor and a zinc precursor, wherein at least one of the first accelerant and the second accelerant is a chemical promoter,
wherein the cadmium precursor employed is a cadmium oxide, a halogenated cadmium compound, or a cadmium salt,
wherein the nanoparticles have a peak emission wavelength that is at least 50 nm longer than that of identically sized nanoparticles composed of Cd and Se, and no Te.
2. The method of claim 1 , wherein both the first accelerant and the second accelerant are chemical promoters.
3. A method for preparing quantum dot nanoparticles that exhibit emission in the red or infrared spectral range which comprises; (i) combining a cadmium precursor, a selenium precursor, and a tellurium precursor in a solvent, wherein the mole ratio of tellurium to selenium is in the range of about 0.01 to about 0.10; (ii) inducing formation of a nanoparticle core using a first accelerant; (iii) combining the nanoparticle core with a solvent, a sulfur precursor, a second accelerant, and a cadmium precursor, a zinc precursor, or both a cadmium precursor and a zinc precursor, wherein one of the first accelerant and the second accelerant is heat and the other is a chemical promoter,
wherein the cadmium precursor employed is a cadmium oxide, a halogenated cadmium compound, or a cadmium salt,
wherein the nanoparticles have a peak emission wavelength that is at least 50 nm longer than that of identically sized nanoparticles composed of Cd and Se, and no Te.
4. The method of claim 1 , wherein the chemical promoter is a reducing agent capable of reducing cadmium(II), zinc(II), selenium(0), tellurium(0), or sulfur(0).