Quantum dot having a phosphorus precursor in a multi-component core
A quantum dot including a multi-component core including a first semiconductor nanocrystal including indium (In), zinc (Zn), and phosphorus (P) and a second semiconductor nanocrystal disposed on the first semiconductor nanocrystal, the second semiconductor nanocrystal including gallium (Ga) and phosphorus (P) wherein the quantum dot is cadmium-free and emits green light, a mole ratio (P:In) of phosphorus relative to indium is greater than or equal to about 0.6:1 and less than or equal to about 1.0, and a mole ratio (P:(In+Ga)) of phosphorus relative to indium and gallium is greater than or equal to about 0.5:1 and less than or equal to about 0.8:1, a quantum dot-polymer composite pattern including the same, and a display device.
1. A method of producing a quantum dot having a multi-component core, comprising:
forming the multi-component core,
wherein the forming the multi-component core comprises
reacting an indium precursor with a phosphorus precursor at a first reaction temperature in an organic solvent in the presence of an organic ligand to form first particles comprising a first semiconductor nanocrystal, the first semiconductor nanocrystal comprising indium and phosphorus;
adding a zinc precursor to the first particles at a temperature equal to or less than the first reaction temperature to form a zinc-containing coating on a surface of the first particles, whereby providing a reaction system that comprises second particles on which the zinc-containing coating is formed; and
adding a gallium precursor and a phosphorus precursor to the reaction system that comprises the second particles while heating the reaction system to a second reaction temperature to form a second semiconductor nanocrystal on the second particles to obtain a multi-component core, whereby producing the quantum dot having the multi-component core,
wherein the second reaction temperature is higher than the first reaction temperature,
wherein the quantum dot emits green light, and
wherein in the quantum dot a mole ratio of phosphorus relative to indium is greater than or equal to about 0.6:1 and less than or equal to about 1.0:1, and a mole ratio of phosphorus relative to a sum of indium and gallium is greater than or equal to about 0.5:1 and less than or equal to about 0.8:1.
2. The method of claim 1 , wherein the forming the multi-component core is performed by one-pot synthesis without separation of the produced particles.
3. The method of claim 1 , wherein the first reaction temperature is less than or equal to about 150° C. and the second reaction temperature is greater than or equal to about 160° C. and less than or equal to about 280° C.
4. The method of claim 1 , wherein the indium precursor comprises indium halide, indium nitrate, indium hydroxide, indium fluoride, indium chloride, indium bromide, indium iodide, indium oxide, indium sulfate, indium carboxylate, indium acetate, indium acetylacetonate, or a combination thereof.
5. The method of claim 1 , wherein the zinc precursor comprises a Zn metal powder, an alkylated Zn compound, a Zn alkoxide, a Zn carboxylate, Zn nitrate, Zn chlorate, Zn sulfate, Zn acetylacetonate, a Zn halide, Zn cyanide, Zn hydroxide, Zn oxide, Zn peroxide, or a combination thereof.
6. The method of claim 1 , wherein the gallium precursor comprises gallium chloride, gallium acetylacetonate, gallium fluoride, gallium oxide, gallium nitrate, gallium sulfate, gallium bromide, gallium iodide, or a combination thereof.
7. The method of claim 1 , wherein the organic ligand is represented by RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH 2 PO, R 2 HPO, R 3 PO, RH 2 P, R 2 HP, R 3 P, ROH, RCOOR′, RPO(OH) 2 , RHPOOH, R 2 POOH, wherein, R and R′ are independently a C1 to C24 aliphatic hydrocarbon, a C6 to C20 aromatic hydrocarbon, or a combination thereof.
8. The method of claim 1 , wherein the quantum dot exhibits a first absorption peak of less than or equal to about 440 nanometers and an optical density at a wavelength of about 450 nanometers per gram of greater than or equal to about 1,100 in an ultraviolet-visible absorption spectrum.
9. The method of claim 1 , wherein a maximum emission peak of the green light is in a range of about 500 nanometers to about 550 nanometers.
10. The method of claim 1 , wherein the quantum dot has a ratio of intensity at a wavelength of about 450 nanometers relative to an intensity at a wavelength of about 350 nanometers of greater than or equal to about 0.5:1 in an ultraviolet-visible absorption spectrum.
11. The method of claim 1 , wherein when a first absorption peak in an ultraviolet-visible absorption spectrum of the quantum dot is less than or equal to about 440 nanometers, the quantum dot has a mole ratio of phosphorus relative to a sum of indium, zinc, and gallium of greater than or equal to about 0.2:1 and less than about 0.77:1.
12. The method of claim 1 , wherein when a first absorption peak in an ultraviolet-visible absorption spectrum of the quantum dot is less than or equal to about 440 nanometers, the quantum dot has a mole ratio of a sum of zinc and gallium relative to indium of less than about 0.75:1.
13. The method of claim 1 , wherein a diameter of the multi-component core is greater than or equal to about 2.3 nanometers and less than or equal to about 3.0 nanometers.
14. The method of claim 1 , further comprising:
forming a shell on the multi-component core of the quantum dot,
wherein the forming a shell on the multi-component core comprises
preparing a first mixture comprising a zinc precursor, an organic ligand, and an organic solvent;
adding the obtained multi-component core and a selenium-containing precursor to the first mixture to obtain a second mixture;
heating the second mixture up to a shell-forming temperature to obtain a third mixture that comprises third particles having a first semiconductor nanocrystal shell comprising zinc and selenium on the multi-component core; and
adding a sulfur-containing precursor to the third mixture at the shell-forming temperature and performing a reaction to form a second semiconductor nanocrystal shell comprising zinc and sulfur on the first semiconductor nanocrystal shell.
15. The method of claim 14 , wherein the shell-forming temperature is greater than or equal to about 280° C.
16. The method of claim 14 , wherein the selenium-containing precursor comprises selenium-trioctylphosphine (Se-TOP), selenium-tributylphosphine (Se-TBP), selenium-triphenylphosphine (Se-TPP), tellurium tributylphosphine (Te-TBP), or a combination thereof.
17. The method of claim 14 , wherein the sulfur-containing precursor comprises hexane thiol, octane thiol, decane thiol, dodecane thiol, hexadecane thiol, mercapto propyl silane, sulfur-trioctylphosphine (S-TOP), sulfur-tributylphosphine (S-TBP), sulfur-triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), trimethylsilyl sulfur, ammonium sulfide, sodium sulfide, or a combination thereof.
18. The method of claim 14 , wherein the quantum dot has a mole ratio of zinc relative to a sum of indium and gallium of greater than or equal to about 8:1 and less than or equal to about 45:1.
19. The method of claim 14 , wherein the quantum dot has a mole ratio of a sum of indium and gallium relative to a sum of selenium and sulfur of greater than or equal to about 0.03:1 and less than or equal to about 0.15:1.
20. The method of claim 1 , wherein the quantum dot has a quantum efficiency of greater than or equal to about 60% and has a full width at half maximum of less than or equal to about 50 nanometers.