Quantum dots and preparation method thereof, and optical member and electronic device each including quantum dots
A quantum dot, a method of preparing the quantum dot, and an optical member and an electronic device, each including the quantum dot, are provided. The quantum dot includes: a core including a Group III-V semiconductor compound alloyed with gallium (Ga); a first shell surrounding the core; and a second shell surrounding the first shell, wherein the first shell includes a first compound that includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, the second shell includes a second compound that includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, the first compound and the second compound are different from each other, and the atomic percentages of specific elements in a material of the core, elemental ratios in the first shell and second shell with respect to the core satisfy certain ranges.
1. A quantum dot comprising:
a core comprising a Group III-V semiconductor compound alloyed with gallium (Ga);
a first shell around the core; and
a second shell around the first shell,
wherein the first shell comprises a first compound, which comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound,
the second shell comprises a second compound, which comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, and the first compound and the second compound are different from each other,
an atomic percentage of gallium in the core to the Group III element excluding Ga in the core is 25 atomic % to 30 atomic %,
an atomic percentage of the Group V or VI element in the first shell to the Group III element in the core is 5 atomic % to 50 atomic %, and
an atomic percentage of the Group V or VI element in the second shell to the Group III element in the core is 5 atomic % to 50 atomic %.
2. The quantum dot of claim 1 , wherein the Group III-V semiconductor compound alloyed with gallium in the core comprises InGaP.
3. The quantum dot of claim 1 , wherein the Group II-VI semiconductor compound in the first shell and the second shell comprises ZnSe, ZnS, ZnTe, ZnO, ZnMgSe, ZnMgS or a combination thereof, the Group III-V semiconductor compound in the first shell and the second shell comprises GaP, GaAs, GaSb, InAs, InSb, AlP, AlAs, AlSb, or a combination thereof, and the Group III-VI semiconductor compound in the first shell and the second shell comprises GaSe, GaTe, or a combination thereof.
4. The quantum dot of claim 1 , wherein the first shell comprises ZnSe and the second shell comprises ZnS.
5. The quantum dot of claim 1 , wherein the first shell and the second shell each independently comprise a different Group II-VI semiconductor compound,
an atomic percentage of the Group VI element in the first shell to the Group III element in the core is 10 atomic % to 15 atomic %, and
an atomic percentage of the Group VI element in the second shell to the Group III element in the core is 10 atomic % to 15 atomic %.
6. The quantum dot of claim 1 , wherein a weight absorption coefficient of the quantum dot is 350 to 1000 mL·g −1 ·cm −1 ata wavelength of 450 nm.
7. The quantum dot of claim 1 , wherein the quantum dot has a quantum efficiency of 90% or greater.
8. The quantum dot of claim 1 , wherein a maximum emission wavelength in a photoluminescence spectrum of the quantum dot is 520 nm to 530 nm.
9. The quantum dot of claim 1 , wherein a full width at half maximum (FWHM) of a photoluminescence (PL) spectrum of the quantum dot is 40 nm or less.
10. The quantum dot of claim 1 , wherein the quantum dot has a sphericity of 0.7 to 0.9.
11. The quantum dot of claim 1 , wherein the first shell has a thickness of 0.5 nm to 3 nm, and
the second shell has a thickness of 0.5 nm to 4 nm.
12. A method of preparing a quantum dot, the method comprising:
preparing a first mixture in which a core, which comprises a Group III-V semiconductor compound alloyed with gallium (Ga), is dispersed at a concentration of 0.1 mM to 100 mM in an organic solvent;
forming a first shell by reacting a second mixture in which a first precursor, which comprises a Group V element or a Group VI element, and a second precursor, which comprises a Group II element or a Group III element, are added to the first mixture; and
forming a second shell by reacting a third mixture in which a third precursor, which comprises a Group V element or a Group VI element, and a fourth precursor, which comprises a Group II element or a Group III element, are added to the second mixture,
wherein an atomic percentage of gallium in the core to the Group III element excluding Ga in the core is 25 atomic % to 30 atomic %,
the first precursor and the third precursor are different from each other,
the first shell comprises a first compound, which comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, and the second shell comprises a second compound, which comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound.
13. The method of claim 12 , wherein the Group III-V semiconductor compound alloyed with gallium comprises InGaP.
14. The method of claim 12 , wherein the first precursor comprises trioctylphosphine-selenide (TOP-Se).
15. The method of claim 12 , wherein the third precursor comprises trioctylphosphine-sulfide (TOP-S).
16. The method of claim 12 , wherein the second precursor and the fourth precursor each independently comprise zinc oleate, zinc acetate, zinc acetylacetonate, zinc stearate, or any combination thereof.
17. The method of claim 12 , wherein the forming of the first shell is performed in a temperature range of 240° C. to 340° C.
18. The method of claim 12 , wherein the forming of the second shell is performed in a temperature range of 240° C. to 340° C.
19. An optical member comprising the quantum dot of claim 1 .
20. An electronic device comprising the quantum dot of claim 1 .