Electroluminescent device, and display device comprising thereof

1. An electroluminescent device, comprising

a first electrode and a second electrode facing each other;

an emission layer disposed between the first electrode and the second electrode and comprising

a plurality of quantum dots, and

a first hole transporting material comprising an unsubstituted C4 to C20 alkyl group attached to a backbone structure, wherein the first hole transporting material is a non-polymeric compound;

a hole transport layer disposed between the emission layer and the first electrode and comprising a second hole transporting material;

an electron transport layer disposed between the emission layer and the second electrode; and

wherein the first hole transporting material is a fluorenyl amine compound and the unsubstituted C4 to C20 alkyl group is attached to a fluorenyl group of the fluorenyl amine compound.

2. The electroluminescent device of claim 1 , wherein the first hole transporting material comprises a compound represented by Chemical Formula 1:

wherein, in Chemical Formula 1,

R 1 and R 2 is each independently the unsubstituted C4 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C3 to C20 heteroaryl group, a substituted or unsubstituted C2 to C40 alkylamine group, or a substituted or unsubstituted C12 to C40 arylamine group,

X 1 and X 2 are each independently N or C(—R a ), and X 3 and X 4 are each independently S, N—R b , or C(—R c )(—R d ), wherein R a , R b , R c , and R d are each a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or asubstituted or unsubstituted C3 to C20 heteroaryl group,

L 1 and L 2 are each independently a single bond, a substituted or unsubstituted methylene group, or a substituted or unsubstituted C2 to C4 alkenylene group,

i is 1, and

j, k, l, and m are each independently 0 or 1, and

wherein the substituted refers to the case where a hydrogen atom in a given group is substituted with a halogen atom, a hydroxyl group, an alkoxy group, a C1 to C20 alkyl group, a C6-C30 aryl group, or a combination thereof.

3. The electroluminescent device of claim 2 , wherein the first hole transporting material comprises a compound represented by Chemical Formula 2:

wherein, in Chemical Formula 2,

X 3 , X 4 , L 2 , j, k, l, and m are the same as defined in Chemical Formula 1 of claim 2 ,

R 1 and R 2 is each independently the unsubstituted C4 to C20 alkyl group,

R 3 to R 8 are each independently a substituted or unsubstituted C4 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C3 to C20 heteroaryl group, a substituted or unsubstituted C2 to C40 alkylamine group, or a substituted or unsubstituted C12 to C40 arylamine group.

4. The electroluminescent device of claim 3 , wherein R 1 and R 2 are an octyl group, an decyl group, or an hexadecyl group.

5. The electroluminescent device of claim 3 , wherein the first hole transporting material comprises at least one of compounds represented by Chemical Formula 2-1 to Chemical Formula 2-2:

wherein, in Chemical Formula 2-1 to Chemical Formula 2-2,

X 3 and X 4 are the same as defined in Chemical Formula 1 of claim 2 ,

R 11 , R 12 , R 21 , and R 22 is each independently the unsubstituted C4 to C20 alkyl group,

R 13 , R 14 , R 15 , R 16 , R 23 , R 24 , R 25 , and R 26 are each independently a substituted or unsubstituted C4 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C3 to C20 heteroaryl group, provided that at least one of R 11 to R 14 and at least one of R 21 to R 26 are a substituted or unsubstituted C4 to C20 alkyl group,

R 27 and R 28 are each independently a substituted or unsubstituted C2 to C40 alkylamine group, a substituted or unsubstituted C12 to C40 arylamine group, or a substituted or unsubstituted carbazolyl group.

6. An electroluminescent device, comprising

a first electrode and a second electrode facing each other;

an emission layer disposed between the first electrode and the second electrode and comprising

a plurality of quantum dots, and

a first hole transporting material comprising a substituted or unsubstituted C4 to C20 alkyl group attached to a backbone structure, wherein the first hole transporting material is a non-polymeric compound;

a hole transport layer disposed between the emission layer and the first electrode and comprising a second hole transporting material; and

an electron transport layer disposed between the emission layer and the second electrode,

wherein the first hole transporting material comprises a compound represented by Chemical Formula B, a compound represented by Chemical Formula C, a compound represented by Chemical Formula D, a compound represented by Chemical Formula F, or a combination thereof:

7. The electroluminescent device of claim 1 , wherein the first hole transporting material is soluble in a non-polar solvent.

8. The electroluminescent device of claim 1 , wherein the first hole transporting material is included in an amount of greater than or equal to 2 weight percent and less than 50 weight percent based on a total weight of the emission layer.

9. The electroluminescent device of claim 1 , wherein a root mean square roughness of a surface of the emission layer measured by atomic-force microscopy (AFM) is about 0.5 to about 2.0.

10. The electroluminescent device of claim 1 , wherein the plurality of quantum dots further comprises a hydrophobic ligand bound to a surface thereof.

11. The electroluminescent device of claim 1 , wherein the plurality of quantum dots comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV element or compound, a Group compound, a Group I-II-IV-VI compound, or a combination thereof,

wherein the plurality of quantum dots does not comprise cadmium, and

the plurality of quantum dots further comprises a ligand bound to a surface thereof and the ligand comprises a C4 to C20 alkyl group, a C4 to C20 alkenyl group, a C4 to C20 alkynyl group, or a combination thereof; and a hydroxyl group or a carboxyl group.

12. The electroluminescent device of claim 1 , wherein the plurality of quantum dots has a core-shell structure.

13. The electroluminescent device of claim 1 , wherein the second hole transporting material and the first hole transporting material are a different material.

14. The electroluminescent device of claim 13 , wherein the second hole transporting material comprises a poly(3,4-ethylenedioxythiophene) or derivative thereof, a poly(styrenesulfonate) or derivative thereof, a poly(N-vinylcarbazole) or derivative thereof, a poly(phenylene vinylene) or derivative thereof, a poly(C1 to C10 alkyl) (meth)acrylate) or derivative thereof, a poly(C6 to C40 arylamine) or derivative thereof, a polyaniline or derivative thereof, a polypyrrole or derivative thereof, a poly(9,9-dioctylfluorene) or derivative thereof, a poly(spiro-fluorene) or derivative thereof, a poly-(N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine) or derivative thereof, NiO, MoO 3 , or a combination thereof.

15. The electroluminescent device of claim 1 , wherein the electron transport layer comprises an inorganic nanoparticle, a quinolone compound, a triazine compound, a quinoline compound, a triazole compound, a naphthalene compound, or a combination thereof.

16. The electroluminescent device of claim 1 , wherein the electron transport layer comprises a plurality of inorganic nanoparticles.

17. The electroluminescent device of claim 1 , wherein the electron transport layer has an average thickness of about 20 nanometers to about 100 nanometers.

18. The electroluminescent device of claim 1 , wherein the emission layer has an average thickness of about 15 nanometers to about 100 nanometers.

19. The electroluminescent device of claim 1 , further comprising a hole injection layer disposed between the first electrode and the hole transport layer.

20. A display device comprising the electroluminescent device of claim 1 .

21. The electroluminescent device of claim 1 , wherein the fluorenyl amine compound is substituted with a C6 to C20 aryl group, a C6 to C20 heteroaryl group, or a combination thereof and wherein the substituted or unsubstituted C4 to C20 alkyl group is attached to the 9 position of a fluorenyl group of the fluorene compound.

22. The electroluminescent device of claim 1 , wherein the plurality of quantum dots further comprises a fatty acid compound bound to a surface.

23. The electroluminescent device of claim 1 , wherein the unsubstituted C4 to C20 alkyl group comprises a C8 to C20 alkyl group.

24. The electroluminescent device of claim 1 , wherein the electroluminescent device exhibits a T50 of greater than 1000 hours, wherein the T50 is the time elapsed until a luminance of the electroluminescent device is 50% of an initial luminance thereof.

25. The electroluminescent device of claim 1 , wherein the plurality of quantum dots further comprises a ligand and the plurality of quantum dots does not comprise silicon.

26. An electroluminescent device, comprising

a first electrode and a second electrode facing each other;

an emission layer disposed between the first electrode and the second electrode and comprising

a plurality of quantum dots, and

a first hole transporting material comprising an unsubstituted C4 to C20 alkyl group attached to a backbone structure, wherein the first hole transporting material is a non-polymeric compound;

a hole transport layer disposed between the emission layer and the first electrode and comprising a second hole transporting material;

an electron transport layer disposed between the emission layer and the second electrode;

wherein the first hole transporting material is a fluorenyl amine compound and the unsubstituted C4 to C20 alkyl group is attached to a fluorenyl group; and

wherein the plurality of quantum dots further comprises a ligand and the plurality of quantum dots does not comprise silicon.