Core-shell quantum dot, preparation method thereof, and electroluminescent light-emitting device containing the same

A method for preparing core-shell quantum dot, wherein comprising steps of:

• S1, heating a cadmium precursor, an elemental substance sulfur, an elemental substance selenium, and a ligand in a first solvent to react for preparing a first system containing CdSeXS(1-X) cores, purifying said first system to obtain said CdSeXS(1-X) cores, and dispersing said CdSeXS(1-X) cores in a second solvent to obtain a CdSeXS(1-X) core solution;
• S2, mixing a first shell raw material and said CdSeXS(1-X) core solution and heating to react for growing a first shell on said CdSeXS(1-X) cores, and obtaining a CdSeXS(1-X) core/first shell solution after the reaction;
• S3, mixing a second shell raw material and said CdSeXS(1-X) core/first shell solution and heating to react for growing a second shell on said first shell, obtaining a third system containing CdSeXS(1-X) core/first shell/second shell after the reaction, and purifying said third system to obtain CdSeXS(1-X) core/first shell/second shell;
• wherein, said first shell raw material and said second shell raw material comprise an anionic precursor, a cationic precursor and a ligand correspondingly, said anionic precursor of said first shell being selected from one or two of elemental substance selenium and elemental substance sulfur, said cationic precursor of said first shell being selected from one or two of cadmium precursor and zinc precursor, said anionic precursor of said second shell being elemental substance sulfur, said cationic precursor of said second shell being selected from one or two of cadmium precursor and zinc precursor;
• in said S2 or said S3, a reaction temperature of said heating reaction is 280˜310° C.