Quantum dots and devices including the same
A quantum dot including: a core including a first semiconductor nanocrystal material including zinc, tellurium, and selenium; and a semiconductor nanocrystal shell disposed on the core, the semiconductor nanocrystal shell including zinc, selenium, and sulfur, wherein the quantum dot does not include cadmium, and in the quantum dot, a mole ratio of the sulfur with respect to the selenium is less than or equal to about 2.4:1. A production method of the quantum dot and an electronic device including the same are also disclosed.
1. An electroluminescent device comprising
a first electrode and a second electrode, and
a light emitting layer disposed between the first electrode and the second electrode,
wherein the light emitting layer comprises a quantum dot,
wherein the quantum dot comprises:
zinc, selenium, tellurium, and sulfur,
wherein the quantum dot does not comprise cadmium,
wherein in the quantum dot, a mole ratio of sulfur with respect to selenium is less than or equal to about 2.4:1,
wherein the quantum dot in the light emitting layer is configured to emit blue light having a maximum peak emission wavelength of greater than or equal to 450 nanometers and less than or equal to about 480 nanometers upon a voltage application, and
wherein a peak external quantum efficiency of the electroluminescent device is greater than or equal to about 4%.
2. The electroluminescent device of claim 1 , wherein the quantum dot does not comprise an indium phosphide, copper, or a combination thereof.
3. The electroluminescent device of claim 1 , wherein the quantum dot has a size of greater than or equal to about 10 nanometers and less than or equal to about 50 nanometers.
4. The electroluminescent device of claim 1 ,
wherein the quantum dot further comprises tellurium and optionally wherein in the quantum dot, a mole ratio of tellurium with respect to selenium is less than or equal to about 0.02:1.
5. The electroluminescent device of claim 4 , wherein in the quantum dot, a mole ratio of tellurium with respect to selenium is in a range of greater than or equal to about 0.001:1 and less than or equal to about 0.01:1.
6. The electroluminescent device of claim 1 , wherein in the quantum dot, the mole ratio of sulfur with respect to selenium is less than or equal to about 2.0:1.
7. The electroluminescent device of claim 1 , wherein in the quantum dot, a mole ratio of sulfur with respect to selenium is less than or equal to about 1.85:1.
8. The electroluminescent device of claim 1 , wherein the quantum dot has a core shell structure wherein a core comprising a first semiconductor nanocrystal material comprising zinc, tellurium, and selenium and a semiconductor nanocrystal shell disposed on the core and comprising a second semiconductor nanocrystal comprising zinc, selenium, and sulfur.
9. The electroluminescent device of claim 1 , wherein in the quantum dot, a mole ratio of selenium with respect to zinc is greater than or equal to about 0.1:1 and less than or equal to about 0.95:1.
10. The electroluminescent device of claim 1 , wherein in the quantum dot, a mole ratio of sulfur with respect to zinc is greater than or equal to about 0.1:1 and less than or equal to about 0.9:1.
11. The electroluminescent device of claim 1 , wherein in the quantum dot, a mole ratio of a sum of selenium and sulfur with respect to zinc is greater than or equal to about 0.3:1 and less than or equal to about 1:1.
12. The electroluminescent device of claim 1 , wherein the maximum peak wavelength is from about 455 nanometers to about 475 nanometers.
13. The electroluminescent device of claim 1 , wherein the maximum peak wavelength is from about 460 nanometers to about 475 nanometers.
14. The electroluminescent device of claim 1 , wherein the peak external quantum efficiency is greater than or equal to about 6.3%.
15. The electroluminescent device of claim 1 , wherein the quantum dot has a size of greater than or equal to about 12 nanometers and less than or equal to about 45 nanometers.
16. The electroluminescent device of claim 1 , wherein the peak external quantum efficiency is greater than or equal to about 6.5%.
17. The electroluminescent device of claim 1 , further comprising a charge auxiliary layer between the first electrode and the light emitting layer, between the second electrode and the light emitting layer, or between the first electrode and the light emitting layer and between the second electrode and the light emitting layer.
18. The electroluminescent device of claim 17 , wherein the charge auxiliary layer comprises a charge injection layer, a charge transport layer, or a combination thereof.
19. The electroluminescent device of claim 1 , wherein the electroluminescent device emits light having an x value of a CIE color space chromaticity diagram that is less than or equal to about 0.2.
20. A quantum dot comprising:
zinc, selenium, tellurium, and sulfur,
wherein the quantum dot does not comprise cadmium,
wherein in the quantum dot, a mole ratio of sulfur with respect to selenium is less than or equal to about 2.4:1,
wherein the quantum dot is configured to emit blue light having a maximum peak emission wavelength of greater than or equal to 450 nanometers and less than or equal to about 480 nanometers; and
wherein the quantum dot has a quantum efficiency of greater than or equal to about 70%.