Granted Patent B2

US 12,302,685 · App. 18/645,743 · Granted May 13, 2025

Inventors: Satoshi Seo (Kanagawa, JP); Hiromi Seo (Kanagawa, JP); Kunihiko Suzuki (Kanagawa, JP); Kanta Abe (Kanagawa, JP); Yuji Iwaki (Kanagawa, JP); Naoaki Hashimoto (Kanagawa, JP); Tsunenori Suzuki (Kanagawa, JP)

Assignee: Semiconductor Energy Laboratory Co., Ltd.

H10K50/16H10K50/11H10K50/15H10K50/171H10K50/81H10K50/82H10K59/00H10K85/321H10K2101/40

Abstract

Claims (67)

1. A light-emitting device comprising:

an anode;

a cathode; and

an EL layer between the anode and the cathode,

wherein the EL layer includes a light-emitting layer and an electron-transport layer,

wherein the electron-transport layer is positioned between the light-emitting layer and the cathode,

wherein the electron-transport layer comprises a first material having a first resistance in a state where no current is flowing between the anode and the cathode and a second resistance in a state where a current is flowing between the anode and the cathode,

wherein the first resistance is higher than the second resistance,

wherein the first material comprises an organic compound having an electron-transport property and an organometallic complex of an alkali metal or an alkaline earth metal,

wherein the organic compound having an electron-transport property comprises an anthracene skeleton and a heterocyclic skeleton, and

wherein the organometallic complex of an alkali metal or an alkaline earth metal comprises a ligand containing nitrogen and oxygen.

2. A light-emitting device comprising:

an anode;

a cathode; and

an EL layer between the anode and the cathode,

wherein the EL layer includes a light-emitting layer and an electron-transport layer,

wherein the electron-transport layer is positioned between the light-emitting layer and the cathode,

wherein the electron-transport layer comprises a first material having a first resistance in a state where no current is flowing between the anode and the cathode and a second resistance in a state where a current is flowing between the anode and the cathode,

wherein the first resistance is higher than the second resistance,

wherein the first material comprises an organic compound having an electron-transport property and an organometallic complex of an alkali metal or an alkaline earth metal,

wherein the organic compound having an electron-transport property comprises an anthracene skeleton and a nitrogen-containing five-membered ring skeleton, and

wherein the organometallic complex of an alkali metal or an alkaline earth metal comprises a ligand containing nitrogen and oxygen.

3. A light-emitting device comprising:

an anode;

a cathode; and

an EL layer between the anode and the cathode,

wherein the EL layer includes a light-emitting layer and an electron-transport layer,

wherein the electron-transport layer is positioned between the light-emitting layer and the cathode,

wherein the electron-transport layer comprises a first material having a first resistance in a state where no current is flowing between the anode and the cathode and a second resistance in a state where a current is flowing between the anode and the cathode,

wherein the first resistance is higher than the second resistance,

wherein the first material comprises an organic compound having an electron-transport property and an organometallic complex of an alkali metal or an alkaline earth metal,

wherein the organic compound having an electron-transport property comprises an anthracene skeleton and a nitrogen-containing five-membered ring skeleton including two heteroatoms in a ring, and

wherein the organometallic complex of an alkali metal or an alkaline earth metal comprises a monovalent metal ion and a ligand having an 8-hydroxyquinolinato structure.

4. The light-emitting device according to claim 1 ,

wherein the electron-transport layer comprises a first layer and a second layer,

wherein the first layer is positioned between the light-emitting layer and the second layer,

wherein the second layer is positioned between the first layer and the cathode, and

wherein a concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is different from that in the second layer.

5. The light-emitting device according to claim 2 ,

wherein the electron-transport layer comprises a first layer and a second layer,

wherein the first layer is positioned between the light-emitting layer and the second layer,

wherein the second layer is positioned between the first layer and the cathode, and

wherein a concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is different from that in the second layer.

6. The light-emitting device according to claim 3 ,

wherein the electron-transport layer comprises a first layer and a second layer,

wherein the first layer is positioned between the light-emitting layer and the second layer,

wherein the second layer is positioned between the first layer and the cathode, and

wherein a concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is different from that in the second layer.

7. The light-emitting device according to claim 4 ,

wherein the concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is higher than that in the second layer.

8. The light-emitting device according to claim 5 ,

wherein the concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is higher than that in the second layer.

9. The light-emitting device according to claim 6 ,

wherein the concentration of the organometallic complex of an alkali metal or an alkaline earth metal in the first layer is higher than that in the second layer.

10. The light-emitting device according to claim 1 ,

wherein the light-emitting layer contains a host material and a light-emitting substance, and

wherein the light-emitting substance emits blue fluorescence.

11. The light-emitting device according to claim 2 ,

wherein the light-emitting layer contains a host material and a light-emitting substance, and

wherein the light-emitting substance emits blue fluorescence.

12. The light-emitting device according to claim 3 , wherein the light-emitting layer contains a host material and a light-emitting substance, and wherein the light-emitting substance emits blue fluorescence.

13. The light-emitting device according to claim 1 , further comprising: a hole-injection layer between the anode and the light-emitting layer, wherein the hole-injection layer comprises a first substance and a second substance.

14. The light-emitting device according to claim 2 , further comprising: a hole-injection layer between the anode and the light-emitting layer, wherein the hole-injection layer comprises a first substance and a second substance.

15. The light-emitting device according to claim 3 , further comprising: a hole-injection layer between the anode and the light-emitting layer, wherein the hole-injection layer comprises a first substance and a second substance.

16. The light-emitting device according to claim 13 , wherein the first substance and the second substance are selected in such a way that a carrier recombination region in the light-emitting device extends to the electron-transport layer at an initial driving stage.

17. The light-emitting device according to claim 14 , wherein the first substance and the second substance are selected in such a way that a carrier recombination region in the light-emitting device extends to the electron-transport layer at an initial driving stage.

18. The light-emitting device according to claim 15 , wherein the first substance and the second substance are selected in such a way that a carrier recombination region in the light-emitting device extends to the electron-transport layer at an initial driving stage.

Priority Claims (1)

Continuity (3)

References Cited (80)