CN-122003022-A - Light emitting device

Abstract

A light emitting device with good reliability is provided. The light emitting device includes a first electrode formed on an insulating surface, a second electrode opposite to the first electrode, and an EL layer between the first electrode and the second electrode, one of the first electrode and the second electrode being an anode and the other being a cathode, the EL layer including a light emitting layer, a first layer and a second layer between the light emitting layer and the cathode, the first layer being between the first electrode and the second layer, and the second layer being between the first layer and the second electrode, the gsp_slope (mV/nm) of the second layer being larger than the gsp_slope (mV/nm) of the first layer (note that gsp_slope (mV/nm) is expressed as Δv/Δd, Δv (mV) is a variation in surface potential with respect to a variation in thickness Δd (nm).

Inventors

• Wood family allowance
• OHKI nobuharu
• WATABE TAKEYOSHI

Assignees

• 株式会社半导体能源研究所

Dates

Publication Date

20260508

Application Date

20251104

Priority Date

20241108

Claims (20)

1. 1. A light emitting device, comprising: a first electrode on the insulating surface; A second electrode opposite to the first electrode, and An EL layer between the first electrode and the second electrode, Wherein the EL layer comprises a light emitting layer, a hole transport layer, a first electron transport layer and a second electron transport layer, The first electron transport layer is located between the light emitting layer and the second electron transport layer, The second electron transport layer is located between the first electron transport layer and the second electrode, The light emitting layer is located between the hole transport layer and the first electron transport layer, The gsp_slope (mV/nm) of the second electron transport layer is greater than the gsp_slope (mV/nm) of the first electron transport layer, And, the GSP_slope (mV/nm) is expressed as DeltaV/Deltad, deltaV (mV) is the variation of the surface potential with respect to the variation of the thickness Deltad (nm).
2. 2. A light emitting device, comprising: a first electrode on the insulating surface; A second electrode opposite to the first electrode, and An EL layer between the first electrode and the second electrode, Wherein the EL layer comprises a light emitting layer, a hole transport layer, a first electron transport layer and a second electron transport layer, The first electron transport layer is located between the light emitting layer and the second electron transport layer, The second electron transport layer is located between the first electron transport layer and the second electrode, The light emitting layer is located between the hole transport layer and the first electron transport layer, The first electron transport layer includes a first organic compound, The second electron transport layer includes a second organic compound, The first organic compound and the second organic compound each independently have a pi-electron deficient heteroaromatic ring, The GSP_slope (mV/nm) of the vapor-deposited film of the second organic compound is larger than the GSP_slope (mV/nm) of the vapor-deposited film of the first organic compound, And, the GSP_slope (mV/nm) is expressed as DeltaV/Deltad, deltaV (mV) is the variation of the surface potential with respect to the variation of the thickness Deltad (nm).
3. 3. A light emitting device according to claim 2, Wherein the second electron transport layer further comprises a first substance.
4. 4. A light emitting device according to claim 3, Wherein when a mixing ratio of the second organic compound and the first substance in the second electron transport layer is x:y, the gsp_slope (mV/nm) of the vapor-deposited film of the second organic compound is greater than (x+y)/x times of the gsp_slope (mV/nm) of the vapor-deposited film of the first organic compound.
5. 5. A light emitting device according to claim 4, Wherein y is x or more.
6. 6. A light emitting device according to claim 1, Wherein the light emitting layer comprises a substance that emits phosphorescence.
7. 7. A light emitting device according to claim 1, Wherein GSP_slope (mV/nm) of the light emitting layer is greater than the GSP_slope (mV/nm) of the first electron transporting layer.
8. 8. A light emitting device according to claim 7, Wherein the GSP_slope (mV/nm) of the light emitting layer is greater than the GSP_slope (mV/nm) of the hole transporting layer.
9. 9. A light emitting device according to claim 2, Wherein the light-emitting layer comprises a host material and a light-emitting substance, And gsp_slope (mV/nm) of the vapor deposited film of the host material is greater than the gsp_slope (mV/nm) of the vapor deposited film of the first organic compound.
10. 10. A light emitting device according to claim 9, Wherein the GSP_slope (mV/nm) of the vapor deposited film of the second organic compound is greater than the GSP_slope (mV/nm) of the vapor deposited film of the host material.
11. 11. A light emitting device according to claim 9, Wherein the hole transport layer comprises a third organic compound, And the GSP_slope (mV/nm) of the light-emitting layer is equal to or greater than the GSP_slope (mV/nm) of the vapor deposition film of the third organic compound.
12. 12. A light emitting device according to claim 9, Wherein the hole transport layer comprises a third organic compound, And the gsp_slope (mV/nm) of the vapor deposition film of the host material is equal to or greater than the gsp_slope (mV/nm) of the vapor deposition film of the third organic compound.
13. 13. A light emitting device according to claim 9, Wherein the host material comprises a first material and a second material, And the first material and the second material are organic compounds that form a combination of exciplex.
14. 14. A light emitting device according to claim 13, Wherein the first material is an organic compound having a pi-electron deficient heteroaromatic ring, And the second material is an organic compound having a pi-electron rich heteroaromatic ring or aromatic amine.
15. 15. A light emitting device according to claim 3, Wherein the first substance is a metal complex.
16. 16. A light emitting device according to claim 15, Wherein the metal complex is an organic complex comprising an alkali metal.
17. 17. A light emitting device according to claim 6, Wherein the peak wavelength of the emission spectrum of the phosphorescence-emitting substance is 450nm or more and 520nm or less.
18. 18. A light emitting device according to claim 9, Wherein the peak wavelength of the emission spectrum of the luminescent material is 450nm or more and 520nm or less.
19. 19. A light emitting device according to claim 2, Wherein the light emitting layer comprises a substance that emits phosphorescence.
20. 20. The light-emitting device according to claim 19, Wherein the peak wavelength of the emission spectrum of the phosphorescence-emitting substance is 450nm or more and 520nm or less.

Description

Light emitting device Technical Field One embodiment of the present invention relates to an organic compound, an organic semiconductor element, a light-emitting element, an organic EL element, a photodiode, a display module, an illumination module, a display device, a light-emitting device, an electronic apparatus, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above-described technical field. The technical field of one embodiment of the invention disclosed in the present specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, machine, product, or composition (composition of matter). Thus, more specifically, as an example of the technical field of one embodiment of the present invention disclosed in the present specification, a semiconductor device, a display device, a liquid crystal display device, a light emitting device, a lighting device, a power storage device, a storage device, an image pickup device, a driving method of these devices, or a manufacturing method of these devices can be given. Background Light emitting devices (organic EL elements) using Electroluminescence (EL) using an organic compound are in very active use. In the basic structure of these organic EL elements, an organic compound layer (EL layer) containing a light-emitting material is sandwiched between a pair of electrodes. By applying a voltage to the device, carriers are injected, and light emission from the light emitting material can be obtained by utilizing the recombination energy of the carriers. Since such an organic EL element is a self-luminous EL element, there are advantages such as higher visibility than liquid crystal when used for a pixel of a display, no need for a backlight, and the like. Further, a display using such an organic EL element can be manufactured to be thin and light, which is also a great advantage. Furthermore, a very fast response speed is also one of the characteristics of the organic EL element. Further, since the light-emitting layer of such an organic EL element can be continuously formed in a planar shape, surface light emission can be obtained. Since this is a feature that is difficult to obtain in a point light source typified by an incandescent lamp or an LED or a line light source typified by a fluorescent lamp, the light-emitting device has high utility value as a surface light source that can be used for illumination or the like. As described above, a display or a lighting device using an organic EL element can be suitably used for various electronic devices, and research and development of an organic EL element having better characteristics are being actively pursued. Non-patent document 1, makou Yu and other 2 names, "oriented polarization phenomenon of polar molecules and interfacial Properties of organic thin film element", journal of the Vacuum Society of Japan,2015, vol.58, no.3 Disclosure of Invention An object of one embodiment of the present invention is to provide a light emitting device with good reliability. Further, another object of the present invention is to provide a light-emitting device having high light-emitting efficiency. An object of one embodiment of the present invention is to provide a light emitting device having a low driving voltage. Further, an object of one embodiment of the present invention is to provide any one of a light-emitting device, an electronic apparatus, and a display device with good reliability. Further, an object of one embodiment of the present invention is to provide a blue phosphorescent light emitting device with high reliability. Further, another object of the present invention is to provide a light-emitting device having high light-emitting efficiency. An object of one embodiment of the present invention is to provide a blue phosphorescent light emitting device having a low driving voltage. Note that the description of these objects does not prevent the existence of other objects. Note that one embodiment of the present invention is not required to achieve all of the above objects. Note that other objects than the above can be obtained and extracted from the description of the specification, drawings, claims, and the like. One embodiment of the present invention is a light emitting device including a first electrode formed on an insulating surface, a second electrode opposite to the first electrode, and an EL layer between the first electrode and the second electrode, the EL layer including a light emitting layer, a hole transporting layer, a first electron transporting layer, and a second electron transporting layer, the first electron transporting layer being between the first electrode and the second electron transporting layer, the light emitting layer being between the hole transporting layer and the first and second electron transporting layers, and gsp_slope