Light-emitting element and display device

Patent metadata

Field	Value
Publication number	US-2022158115-A1
Application number	US-201917434348-A
Country	US
Kind code	A1
Filing date	Mar 4, 2019
Priority date	Mar 4, 2019
Publication date	May 19, 2022
Grant date	—

Abstract

A light-emitting element is provided with an anode, a light-emitting layer including quantum dots, and a cathode. The light-emitting element includes: an electron transport layer provided between the cathode and the light-emitting layer; and a hole tunneling insulating layer provided between the anode and the light-emitting layer and in contact with the anode and the light-emitting layer.

First claim

1 . A light-emitting element provided with an anode, a light-emitting layer including quantum dots, and a cathode, the light-emitting element comprising:
an electron transport layer provided between the cathode and the light-emitting layer; and a hole tunneling insulating layer provided between the anode and the light-emitting layer and in contact with the anode and the light-emitting layer.

2 . The light-emitting element according to claim 1 ,
wherein a thickness of the hole tunneling insulating layer is 0.1 nm or greater and 2.2 nm or less.

3 . The light-emitting element according to claim 1 ,
wherein an electron affinity value of the hole tunneling insulating layer is smaller than an electron affinity value of the light-emitting layer by 0.5 eV or greater, and an ionization potential value of the hole tunneling insulating layer is greater than a value obtained by subtracting 0.5 eV from an ionization potential value of the light-emitting layer.

4 . The light-emitting element according to claim 1 ,
wherein the hole tunneling insulating layer is composed of an inorganic material.

5 . The light-emitting element according to claim 4 ,
wherein the inorganic material includes any one of aluminum oxide, silicon oxide, silicon oxynitride, and silicon nitride.

6 . The light-emitting element according to claim 1 ,
wherein the hole tunneling insulating layer is composed of an organic material.

7 . The light-emitting element according to claim 6 ,
wherein the organic material includes any one of polymethyl methacrylate (PMMA), polyvinyl carbazole (PVK), and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl))diphenylamine)] (TFB).

8 . The light-emitting element according to claim 1 ,
wherein the hole tunneling insulating layer includes a plurality of layers composed of different materials.

9 . The light-emitting element according to claim 1 ,
wherein a band gap of the hole tunneling insulating layer is 3 eV or greater.

10 . The light-emitting element according to claim 1 ,
wherein the electron transport layer includes zinc oxide or titanium oxide.

11 . The light-emitting element according to claim 1 ,
wherein the electron transport layer includes magnesium zinc oxide.

12 . The light-emitting element according to claim 10 ,
wherein the electron transport layer is formed of nanoparticles.

13 . A display device comprising the light-emitting element described in claim 1 .

14 . The display device according to claim 13 ,
wherein a plurality of the light-emitting elements are provided, the plurality of the light-emitting elements include a first light-emitting element, a second light-emitting element, and a third light-emitting element, an emission peak wavelength of the first light-emitting element is longer than an emission peak wavelength of the second light-emitting element; and the emission peak wavelength of the second light-emitting element is longer than an emission peak wavelength of the third light-emitting element.

15 . The display device according to claim 14 ,
wherein the first light-emitting element includes a first light-emitting layer as the light-emitting layer and a first hole tunneling insulating layer as the hole tunneling insulating layer, the second light-emitting element includes a second light-emitting layer as the light-emitting layer and a second hole tunneling insulating layer as the hole tunneling insulating layer, the third light-emitting element includes a third light-emitting layer as the light-emitting layer and a third hole tunneling insulating layer as the hole tunneling insulating layer, the first hole tunneling insulating layer, the second hole tunneling insulating layer, and the third hole tunneling insulating layer are formed of an identical material, electron affinity values of the first hole tunneling insulating layer, the second hole tunneling insulating layer, and the third hole tunneling insulating layer are smaller than the smallest value of an electron affinity value of the first light-emitting layer, an electron affinity value of the second light-emitting layer, and an electron affinity value of the third light-emitting layer by 0.5 eV or greater, and ionization potential values of the first hole tunneling insulating layer, the second hole tunneling insulating layer, and the third hole tunneling insulating layer are larger than a value obtained by subtracting 0.5 eV from the greatest value of an ionization potential value of the first light-emitting layer, an ionization potential value of the second light-emitting layer, and an ionization potential value of the third light-emitting layer.

16 . The display device according to claim 14 ,
wherein the first light-emitting element includes a first light-emitting layer as the light-emitting layer and a first hole tunneling insulating layer as the hole tunneling insulating layer, the second light-emitting element includes a second light-emitting layer as the light-emitting layer and a second hole tunneling insulating layer as the hole tunneling insulating layer, the third light-emitting element includes a third light-emitting layer as the light-emitting layer and a third hole tunneling insulating layer as the hole tunneling insulating layer, the first hole tunneling insulating layer, the second hole tunneling insulating layer, and the third hole tunneling insulating layer are formed of different materials, an electron affinity value of the first hole tunneling insulating layer is smaller than an electron affinity value of the first light-emitting layer by 0.5 eV or greater, an electron affinity value of the second hole tunneling insulating layer is smaller than an electron affinity value of the second light-emitting layer by 0.5 eV or greater, an electron affinity value of the third hole tunneling insulating layer is smaller than an electron affinity value of the third light-emitting layer by 0.5 eV or greater, an ionization potential value of the first hole tunneling insulating layer is greater than a value obtained by subtracting 0.5 eV from an ionization potential value of the first light-emitting layer, an ionization potential value of the second hole tunneling insulating layer is greater than a value obtained by subtracting 0.5 eV from an ionization potential value of the second light-emitting layer, and an ionization potential value of the third hole tunneling insulating layer is greater than a value obtained by subtracting 0.5 eV from an ionization potential value of the third light-emitting layer.

17 . The display device according to claim 16 ,
wherein the electron affinity value of the third hole tunneling insulating layer is greater than the electron affinity value of the second hole tunneling insulating layer; and the electron affinity value of the second hole tunneling insulating layer is greater than the electron affinity value of the first hole tunneling insulating layer.

18 . The display device according to claim 16 ,
wherein the first hole tunneling insulating layer includes any one of silicon oxynitride, silicon oxide, and aluminum oxide.

19 . The display device according to claim 16 ,
wherein the second hole tunneling insulating layer includes any one of aluminum oxide and polyvinyl carbazole (PVK).

20 . The display device according to claim 16 ,
wherein the third hole tunneling insulating layer includes any one of silicon nitride, polyvinyl carbazole (PVK), and polymethyl methacrylate (PMMA).

21

Assignees

• Sharp Kk

Inventors

• Naka Takayuki
• Ueta Yoshihiro
• Iwata Noboru

Classifications

• H10K50/17

  Carrier injection layers · CPC title

• H10K50/18 Primary

  Carrier blocking layers · CPC title

• G09F9/30

  in which the desired character or characters are formed by combining individual elements (panels comprising a number of electrodes in a single cell controlling light arriving from an independent light source, e.g. electro-optical or magneto-optical cell, G02F1/00) · CPC title

• H05B33/22

  characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers · CPC title

• H05B33/14

  characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source} · CPC title