Method of forming gigantic quantum dots
Provided is a method of forming gigantic quantum dots including following steps. A first precursor by mixing zinc acetate (Zn(ac) 2 ), cadmium oxide (CdO), a surfactant, and a solvent together and then performing a first heat treatment is provided. The first precursor includes Zn-complex having the surfactant and Cd-complex having the surfactant. A second precursor containing elements S and Se and trioctylphosphine (TOP) is added into the first precursor to form a reaction mixture. A second heat treatment is performed on the reaction mixture and then cooling the reaction mixture to form the gigantic quantum dots in the reaction mixture.
1. A method of forming gigantic quantum dots comprising:
providing a first precursor by mixing zinc acetate (Zn(ac) 2 ), cadmium oxide (CdO), a surfactant, and a solvent together and then performing a first heat treatment, wherein the first precursor comprises Zn-complex having the surfactant and Cd-complex having the surfactant;
adding a second precursor containing elements S and Se and trioctylphosphine (TOP) into the first precursor to form a reaction mixture; and
performing a second heat treatment on the reaction mixture and then cooling the reaction mixture to form the gigantic quantum dots in the reaction mixture, wherein each of the gigantic quantum dots comprises:
a core constituted of CdSe;
a shell constituted of ZnS and wrapping a surface of the core; and
an alloy configured between the core and the shell, the alloy constituted of Cd, Se, Zn and S, wherein a content of the Cd and Se gradually decreases from the core to the shell, and a content of the Zn and S gradually increases from the core to the shell.
2. The method according to claim 1 , wherein the surfactant comprises oleic acid, trioctylphosphine (TOP) or a combination thereof, and the solvent comprises 1-octadecene, oleic acid, trioctylphosphine (TOP) or a combination thereof.
3. The method according to claim 2 , wherein the first precursor comprises Zn-oleate and Cd-oleate.
4. The method according to claim 1 , wherein a temperature of the first heat treatment is 260° C. to 280° C. and a heating time of the first heat treatment is 3 minutes to 10 minutes.
5. The method according to claim 1 , wherein a temperature of the second heat treatment is 300° C. to 320° C. and a heating time of the second heat treatment is 5 minutes to 30 minutes.
6. The method according to claim 1 , wherein a content of the Zn(ac) 2 is 2-15 mmol, a content of the CdO is 0.2-5 mmol, a content of the surfactant is 7-70 mmol, and a content of the solvent is 40-50 mL based on the total amount of the first precursor.
7. The method according to claim 1 , wherein a content of the element S is 2-12 mmol, a content of the element Se is 0.1-5.0 mmol, and a content of the TOP is 5-10 mL based on the total amount of the second precursor.
8. The method according to claim 1 , wherein a particle size of each of the gigantic quantum dots is equal to or more than 10 nm.
9. The method according to claim 1 , wherein a diameter of the core is 1 to 4 nm, a sum diameter of the alloy and the core is 5 to 8 nm, and a particle size of each of the gigantic quantum dots is 10 nm to 15 nm.
10. The method according to claim 1 , wherein the gigantic quantum dots are capable of emitting light upon excitation with a photoluminescence quantum efficiency equal to or more than 90%.
11. The method according to claim 1 , wherein the gigantic quantum dots are capable of emitting light upon excitation with a photoluminescence quantum efficiency in a range of 90% to 95%.
12. The method according to claim 1 , wherein the core of each of the gigantic quantum dots is capable of absorbing a fixed wavelength range of light of a light source and emitting at least one different wavelength range of light.
13. The method according to claim 1 , wherein the wavelength of light emitted by the core of each of the gigantic quantum dots decreases with increasing of a content of the surfactant during synthesis.