ELECTROLUMINESCENT DEVICE AND DISPLAY DEVICE INCLUDING THE SAME
An electroluminescent device includes a first electrode and a second electrode facing each other; a quantum dot layer disposed between the first electrode and the second electrode and including a plurality of quantum dots; optionally, an electron transport layer between the quantum dot layer and the second electrode; wherein the quantum dot layer is configured to emit first light. The electroluminescent device further includes a first layer including an inorganic nanoparticle between the quantum dot layer and the first electrode, and inorganic nanoparticle includes a metal chalcogenide including a Group II metal and a chalcogen element. The inorganic nanoparticle has a size of greater than or equal to about 0.5 nanometers and less than or equal to about 30 nanometers.
1 . An electroluminescent device comprising:
a first electrode and a second electrode;
a quantum dot layer between the first electrode and the second electrode; and optionally, an electron transport layer between the quantum dot layer and the second electrode, wherein the quantum dot layer comprises a quantum dot and is configured to emit first light,
wherein the electroluminescent device further comprises a first layer comprising an inorganic nanoparticle, the first layer disposed between the quantum dot layer and the first electrode,
wherein the inorganic nanoparticle comprises a metal chalcogenide comprising a Group II metal and a chalcogen element, and
the inorganic nanoparticle has a size of greater than or equal to about 0.5 nanometers and less than or equal to about 30 nanometers.
2 . The electroluminescent device of claim 1 , wherein
the electron transport layer comprises a zinc oxide nanoparticle.
3 . The electroluminescent device of claim 1 , wherein
the quantum dot comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV element or compound, a Group II-III-VI compound, a Group I-III-VI compound, a Group I-II-IV-VI compound, or a combination thereof, and
wherein the first light represents a red light spectrum, a green light spectrum, a blue light spectrum, or a combination thereof, and a full width at half maximum of the emission peak of the first light is greater than or equal to about 1 nanometer and less than or equal to about 55 nanometers.
4 . The electroluminescent device of claim 1 , wherein
the Group II metal comprises a metal comprising zinc, magnesium, calcium, barium, strontium, or a combination thereof, and
the chalcogen element comprises selenium, sulfur, tellurium, or a combination thereof.
5 . The electroluminescent device of claim 1 , wherein
the metal chalcogenide comprises a magnesium sulfide, a magnesium selenide, a magnesium sulfide selenide, a zinc magnesium selenide, a zinc magnesium sulfide, a zinc sulfide, a zinc selenide sulfide, a barium sulfide, a barium selenide, a barium sulfide selenide, a calcium sulfide, a calcium selenide, a calcium selenide sulfide, or a combination thereof.
6 . The electroluminescent device of claim 1 , wherein
a bandgap energy of the metal chalcogenide is greater than or equal to about 3.0 eV and less than or equal to about 6 eV.
7 . The electroluminescent device of claim 1 , wherein
a difference between a LUMO energy level of the metal chalcogenide and a LUMO energy level of the quantum dot layer is greater than or equal to about 0.3 eV.
8 . The electroluminescent device of claim 1 , wherein
the first layer further comprises an organic moiety, and
a mole ratio of carbon to the Group II metal in the first layer is greater than or equal to about 0.001:1 and less than or equal to about 1:1.
9 . The electroluminescent device of claim 1 , wherein
the inorganic nanoparticle has a particle size of greater than or equal to about 1 nanometer and less than or equal to about 10 nanometers.
10 . The electroluminescent device of claim 1 , wherein
the inorganic nanoparticle further comprises an organic ligand on a surface of the inorganic nanoparticle, and
the organic ligand is represented by Chemical Formula 1:
A-L-B Chemical Formula 1
wherein L is a single bond, a substituted or unsubstituted C1 to C50 aliphatic hydrocarbon group, a substituted or unsubstituted C4 to C50 aromatic hydrocarbon group, or a combination thereof, and
A and B are each independently a thiol group, a carboxyl group, a hydroxy group, an amine group, a phosphonic acid group, a phosphoric acid group, a phosphinic acid group, or a moiety derived therefrom.
11 . The electroluminescent device of claim 1 , wherein
the inorganic nanoparticle is configured to be dispersible in water or a water-miscible organic solvent.
12 . The electroluminescent device of claim 10 , wherein
the organic ligand comprises a diacid compound, a mercapto carboxylic acid compound, a mercapto amine compound, a mercapto phosphonic acid compound, a mercapto phosphoric acid compound, a mercapto phosphinic acid compound, a hydroxy carboxylic acid compound, a hydroxy amine compound, a hydroxy phosphonic acid compound, a hydroxy phosphoric acid compound, a hydroxy phosphinic acid compound, or a combination thereof.
13 . The electroluminescent device of claim 1 , further comprising a hole transport layer between the first electrode and the first layer.
14 . The electroluminescent device of claim 13 , wherein
the hole transport layer comprises a hole transporting organic compound, and
the hole transporting organic compound comprising a substituted or unsubstituted fluorenyl moiety, a substituted or unsubstituted diphenylamine moiety, a triphenylamine moiety, or a combination of thereof.
15 . The electroluminescent device of claim 13 , wherein
a LUMO level of the metal chalcogenide is shallower than a LUMO level of the hole transport layer, and
a bandgap energy of the metal chalcogenide is greater than a bandgap energy of the hole transport layer.
16 . The electroluminescent device of claim 13 , further comprising a hole injection layer between the first electrode and the hole transport layer, and
the hole injection layer comprises an organic compound different from the hole transport layer, a hole transporting inorganic material, or a combination thereof.
17 . The electroluminescent device of claim 1 , wherein
the first layer has a thickness of greater than or equal to about 4 nanometers and less than or equal to about 15 nanometers, and optionally wherein the quantum dot layer has a thickness of greater than or equal to about 5 nanometers and less than or equal to about 50 nanometers.
18 . The electroluminescent device of claim 1 , wherein
the first light is blue light; and
wherein the electroluminescent device has a maximum luminance of greater than or equal to about 100,000 candela per square meter, or
wherein the electroluminescent device has a maximum external quantum efficiency of greater than or equal to about 11%,
or a combination thereof.
19 . A display device comprising the electroluminescent device of claim 1 .
20 . The display device of claim 19 , wherein
the display device comprises a portable terminal device, a monitor, a notebook computer, a television, an electric sign board, a camera, or an electronic component for an electric vehicle.