Light-emitting element comprising quantum dots, display device including the same, and manufacturing method of the light-emitting element
A method of manufacturing a light-emitting element includes forming a first electrode, forming a hole transport region by providing a hole transport material on the first electrode, forming a light-emitting layer on the hole transport region, forming an electron transport region on the light-emitting layer, and forming a second electrode on the electron transport region, wherein the forming of the light-emitting layer includes providing, on the hole transport region, a quantum dot composition including an organic solvent and a plurality of quantum dots, heat-treating the quantum dot composition, and vacuum-drying the heat-treated quantum dot composition, so that a light-emitting element in which quantum dots have infiltrated into the hole transport region may be manufactured.
1. A light-emitting element comprising:
a first electrode;
a light-emitting layer on the first electrode and comprising quantum dots;
a hole transport region between the first electrode and the light-emitting layer and comprising a first portion adjacent to the light-emitting layer, the first portion consisting of a hole transport material and quantum dots the same as those comprised in the light-emitting layer, and the first portion having a concentration gradient which is a distribution density of the quantum dots decreasing from a portion of the first portion adjacent to the light-emitting layer to a portion of the first portion further away from the light-emitting layer;
an electron transport region on the light-emitting layer; and
a second electrode on the electron transport region,
wherein an interface is defined between the light-emitting layer and the hole transport region, and
the hole transport material is selected from the group consisting of a compound represented by Formula H-1, a phthalocyanine compound, N,N′-diphenyl-N, N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine (DNTPD), 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4′,4″-tris {N-(2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), polyaniline/camphor sulfonic acid (PANI/CSA), (polyaniline)/poly(4-styrenesulfonate) (PANI/PSS), N,N′-di(naphthalene-1-yl)-N, N′-diphenyl-benzidine (NPB), 4-isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl) borate, a fluorine-based derivative, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), 4,4′-bis[N,N′-(3-tolyl)amino]-3,3′-dimethylbiphenyl (HMTPD), 1,3-Bis(N-carbazolyl)benzene (mCP), 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi), 9-phenyl-9H-3,9′-bicarbazole (CCP), and 1,3-bis(1,8-dimethyl-9H-carbazol-9-yl)benzene (mDCP),
wherein in Formula H-1,
L 1 and L 2 are each independently a substituted or unsubstituted arylene group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 30 ring-forming carbon atoms,
a and b are each independently an integer of 0 to 10,
Ar 1 and Ar 2 are each independently a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, and
Ar 3 is a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms,
wherein a substituent of the substituted arylene group, the substituted heteroarylene group, the substituted aryl group, and the substituted heteroaryl group is selected from the group consisting of a deuterium atom, a halogen atom, a cyano group, a nitro group, an amino group, a silyl group, an oxy group, a sulfinyl group, a sulfonyl group, a carbonyl group, a boron group, a phosphine oxide group, a phosphine sulfide group, an alkyl group, an alkoxy group, a hydrocarbon ring group, an aryl group, and a heterocyclic group.
2. The light-emitting element of claim 1 , wherein the hole transport region comprises the first portion and a second portion not comprising the quantum dots.
3. The light-emitting element of claim 1 , wherein
the hole transport region comprises a plurality of organic layers, and
an organic layer most adjacent to the light-emitting layer from among the plurality of organic layers comprises the quantum dots.
4. The light-emitting element of claim 1 , wherein
the hole transport region comprises a hole injection layer and a hole transport layer on the hole injection layer, and
the hole transport layer comprises the quantum dots, and the hole injection layer does not comprise the quantum dots.
5. The light-emitting element of claim 4 , wherein
the hole transport layer comprises the first portion and a fourth portion not comprising the quantum dots.
6. The light-emitting element of claim 5 , wherein a thickness of the first portion is smaller than a thickness of the fourth portion.
7. The light-emitting element of claim 5 , wherein,
in the first portion, the distribution density of the quantum dots in the portion adjacent to the light-emitting layer is greater than a distribution density of the quantum dots in a portion adjacent to the fourth portion.
8. The light-emitting element of claim 5 , wherein a distribution density of the quantum dots decreases from the first portion to the fourth portion.
9. A display device comprising first to third light-emitting elements configured to emit light having different wavelengths,
wherein each of the first to third light-emitting elements comprises:
a first electrode;
a light-emitting layer on the first electrode and comprising quantum dots;
a hole transport region between the first electrode and the light-emitting layer and consisting of:
a hole transport material, and
quantum dots the same as those comprised in the light-emitting layer;
an electron transport region on the light-emitting layer; and
a second electrode on the electron transport region,
wherein an interface is defined between the light-emitting layer and the hole transport region, and
wherein the hole transport region comprises:
a hole injection layer, and
a hole transport layer on the hole injection layer, the hole transport layer comprising a first portion consisting of the hole transport material and the quantum dots and a fourth portion not comprising the quantum dots, and
wherein, in the first portion, a distribution density of the quantum dots in a portion adjacent to the light-emitting layer is greater than a distribution density of the quantum dots in a portion adjacent to the fourth portion.
10. The display device of claim 9 , wherein
the first light-emitting element comprises a first light-emitting layer comprising first quantum dots configured to emit blue light,
the second light-emitting element comprises a second light-emitting layer comprising second quantum dots configured to emit green light, and
the third light-emitting element comprises a third light-emitting layer comprising third quantum dots configured to emit red light.
11. The display device of claim 10 , wherein
the first light-emitting element comprises a first hole transport region comprising the first quantum dots under the first light-emitting layer,
the second light-emitting element comprises a second hole transport region comprising the second quantum dots under the second light-emitting layer, and
the third light-emitting element comprises a third hole transport region comprising the third quantum dots under the third light-emitting layer.
12. An electronic device comprising a display device,
the display device comprising first to third light-emitting elements configured to emit light having different wavelengths,
wherein each of the first to third light-emitting elements comprises:
a first electrode;
a light-emitting layer on the first electrode and comprising quantum dots;
a hole transport region between the first electrode and the light-emitting layer and consisting of:
a hole transport material, and
quantum dots the same as those comprised in the light-emitting layer;
an electron transport region on the light-emitting layer; and
a second electrode on the electron transport region,
wherein an interface is defined between the light-emitting layer and the hole transport region, and
wherein the hole transport region comprises:
a hole injection layer, and
a hole transport layer on the hole injection layer, the hole transport layer comprising a first portion consisting of the hole transport material and the quantum dots and a fourth portion not comprising the quantum dots, and
wherein, in the first portion, a distribution density of the quantum dots in a portion adjacent to the light-emitting layer is greater than a distribution density of the quantum dots in a portion adjacent to the fourth portion.