Quantum dot composite, quantum dot, device including the same

1. A quantum dot composite comprising

a matrix; and

a plurality of quantum dots and titanium oxide particles dispersed in the matrix,

wherein the quantum dots comprise zinc, selenium, and tellurium,

wherein the quantum dots do not comprise cadmium, wherein the quantum dot composite exhibits a blue light absorption of greater than or equal to about 85%, and

wherein in the quantum dot composite, a weight ratio of tellurium with respect to titanium is greater than or equal to about 1.5:1 and less than or equal to about 3.01:1.

2. The quantum dot composite of claim 1 , wherein the matrix comprises an organic solvent, a polymerizable monomer, a crosslinked polymer, a linear polymer, or a combination thereof.

3. The quantum dot composite of claim 1 , wherein the quantum dots and the titanium oxide particle are intermixed in the matrix.

4. The quantum dot composite of claim 1 , wherein in the quantum dot composite, a weight ratio of zinc with respect to titanium is greater than or equal to about 4:1 and less than or equal to about 11.4:1.

5. The quantum dot composite of claim 1 , wherein in the quantum dot composite, a mole ratio of tellurium with respect to selenium is greater than or equal to about 0.35:1.

6. The quantum dot composite of claim 1 , wherein the quantum dot composite does not comprise an indium phosphide, an indium zinc phosphide, or a combination thereof.

7. The quantum dot composite of claim 1 , wherein the quantum dots comprise a first semiconductor nanocrystal comprising zinc, selenium, and tellurium, and a zinc chalcogenide different from the first semiconductor nanocrystal and comprising selenium, sulfur, or a combination thereof.

8. The quantum dot composite of claim 1 , wherein in the quantum dot composite, a total amount of zinc, tellurium, selenium, sulfur, and titanium is greater than or equal to about 30 weight percent, based on a total weight of the composite, as determined by an inductively coupled plasma atomic emission spectroscopy.

9. The quantum dot composite of claim 1 , wherein in the quantum dot composite, an amount of tellurium is greater than or equal to about 1.5 weight percent, based on a total weight of the composite.

10. The quantum dot composite of claim 1 , wherein the titanium metal oxide particles have an average particle size of greater than or equal to about 100 nanometers and less than or equal to about 500 nanometers.

11. The quantum dot composite of claim 1 , wherein in the quantum dot composite, an amount of titanium is greater than or equal to about 1 weight percent, based on a total weight of the quantum dot composite.

12. The quantum dot composite of claim 1 , wherein the quantum dot composite is configured to emit green light having a maximum luminescent peak with a full width at half maximum of less than or equal to about 40 nanometers.

13. The quantum dot composite of claim 1 , wherein the quantum dot composite has an absorption ratio with respect to blue light of greater than or equal to about 88%.

14. A display device comprising

a light emitting element, and optionally a light source,

wherein the light emitting element comprises the quantum dot composite of claim 1 .

15. An electronic device comprising

a first electrode and a second electrode each having a surface opposite the other; and

an active layer comprising the quantum dot composite of claim 1 disposed between the first and the second electrodes.

16. A method of preparing the quantum dot composite of claim 1 , the method comprising

combining quantum dots comprising zinc, selenium, and tellurium, a dispersing agent, a nd a solvent to prepare a quantum dot dispersion;

mixing the quantum dot dispersion with titanium oxide particles, a photoinitiator, and a polymerizable monomer to form a composition; and

exposing the composition to light to polymerize the polymerizable monomer, form the matrix comprising the quantum dots and titanium oxide particles, and prepare the quantum dot composite.

17. A quantum dot composite comprising

a matrix; and

quantum dots and titanium oxide particles dispersed in the matrix,

wherein the quantum dots comprise zinc, tellurium, and selenium,

wherein the quantum dots do not comprise cadmium, lead, mercury, or a combination thereof,

wherein in the quantum dots, a mole ratio of tellurium with respect to selenium is greater than or equal to about 0.15:1,

wherein the quantum dots are configured to emit green light,

wherein in a thermogravimetric analysis, the quantum dots show a remaining mass of greater than or equal to about 60 weight percent at a temperature of greater than or equal to about 500° C. and less than or equal to about 600° C., based on a total weight of the quantum dots,

wherein the quantum dot composite exhibits a blue light absorption of greater than or equal to about 85%, and

wherein in the quantum dot composite, a weight ratio of tellurium with respect to titanium is greater than or equal to about 1.5:1 and less than or equal to about 3.01:1.

18. The quantum dot composite of claim 17 , wherein the quantum dots exhibit a 5% weight loss temperature of greater than or equal to about 300° C.

19. The quantum dot composite of claim 17 , wherein the quantum dots comprise an organic ligand, and the organic ligand comprises 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, a polymeric organic ligand, or a combination thereof wherein R and R′ are the same or different, and are independently a substituted or unsubstituted C1 to C40 aliphatic hydrocarbon group or a substituted or unsubstituted C6 to C40 aromatic hydrocarbon group, or a combination thereof.

20. The quantum dot composite of claim 17 , wherein a maximum luminescent peak wavelength of the green light or the quantum dots is greater than or equal to about 525 nanometers.

21. The quantum dot composite of claim 17 , wherein the quantum dots show a full width at half maximum of less than or equal to about 40 nanometers and a quantum yield of greater than or equal to about 50%.