CN113437230A - Light emitting device and display panel - Google Patents

Light emitting device and display panel Download PDF

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Publication number
CN113437230A
CN113437230A CN202110683506.7A CN202110683506A CN113437230A CN 113437230 A CN113437230 A CN 113437230A CN 202110683506 A CN202110683506 A CN 202110683506A CN 113437230 A CN113437230 A CN 113437230A
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layer
carrier
light emitting
emitting device
light
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CN113437230B (en
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赵伟
李梦真
姚纯亮
刘彬
许瑾
刘俊
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Yungu Guan Technology Co Ltd
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Yungu Guan Technology Co Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/865—Intermediate layers comprising a mixture of materials of the adjoining active layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/40—Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers

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  • Electromagnetism (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The application discloses light emitting device and display panel, light emitting device include first electrode, second electrode and be located the light emitting structure layer between first electrode and the second electrode, and the light emitting structure layer includes: a light emitting layer including a host material and a guest material, a first carrier mobility of the host material being smaller than a second carrier mobility of the host material; a first carrier function layer located between the first electrode and the light emitting layer; and the current carrier adjusting layer is positioned between the light emitting layer and the first current carrier functional layer, and the main body material and the current carrier adjusting layer are both selected from the light emitting main body material group with the same color. The application can improve the luminous efficiency of the light-emitting device.

Description

Light emitting device and display panel
Technical Field
The application relates to the technical field of display, in particular to a light-emitting device and a display panel.
Background
Organic Light Emitting Diodes (OLEDs), as a novel display technology, have the advantages of high color gamut, foldability, fast response speed, and the like, so the market share of the OLED display panel increases year by year.
In the OLED display panel, in order to improve product competitiveness, device efficiency needs to be further improved, and product power consumption needs to be reduced. However, in the existing OLED display panel, the problems that the transmission rates of the light-emitting host material to electrons and holes are different, and the holes and electrons are not balanced after the light-emitting host material is doped with the guest material, result in low device efficiency and high product power consumption.
Disclosure of Invention
The embodiment of the application provides a light-emitting device and a display panel.
In a first aspect, an embodiment of the present application provides a light emitting device, including a first electrode, a second electrode, and a light emitting structure layer located between the first electrode and the second electrode, where the light emitting structure layer includes: a light emitting layer including a host material and a guest material, a first carrier mobility of the host material being smaller than a second carrier mobility of the host material; a first carrier function layer located between the first electrode and the light emitting layer; and the current carrier adjusting layer is positioned between the light emitting layer and the first current carrier functional layer, and the main body material and the current carrier adjusting layer are both selected from the light emitting main body material group with the same color.
According to the foregoing embodiments of the first aspect of the present application, the material of the carrier adjustment layer is identical to the host material.
According to any one of the preceding embodiments of the first aspect of the present application, the host material comprises a first sub-host material and a second sub-host material, the first carrier mobility of the first sub-host material is less than the second carrier mobility of the first sub-host material, and the first carrier mobility of the second sub-host material is greater than the second carrier mobility of the second sub-host material;
according to any of the preceding embodiments of the first aspect of the present application, the material of the carrier adjusting layer is a second sub-host material; or the first color light-emitting main body material group comprises a third sub-main body material, the material of the carrier adjusting layer is the third sub-main body material, and the first carrier mobility of the third sub-main body material is larger than the second carrier mobility of the third sub-main body material.
According to any of the preceding embodiments of the first aspect of the present application, the ratio of the thicknesses of the carrier adjusting layer and the light emitting layer is 1:15 to 1: 3.
According to any of the preceding embodiments of the first aspect of the present application, the thickness of the carrier adjusting layer is 5-10nm and the thickness of the light emitting layer is 30-45 nm.
According to any of the preceding embodiments of the first aspect of the present application, the first electrode is an anode, the first carriers are holes, the second electrode is a cathode, and the second carriers are electrons.
According to any one of the preceding embodiments of the first aspect of the present application, the highest occupied molecular orbital level of the material of the carrier adjusting layer is less than the highest occupied molecular orbital level of the material of the first carrier functional layer and is greater than or equal to the highest occupied molecular orbital level of the host material.
According to any one of the preceding embodiments of the first aspect of the present application, the first carrier functional layer comprises a hole transport layer, and the highest occupied molecular orbital level of the material of the carrier adjusting layer is smaller than the highest occupied molecular orbital level of the material of the hole transport layer.
According to any one of the preceding embodiments of the first aspect of the present application, the highest occupied molecular orbital level of the material of the carrier adjusting layer is from-6.0 eV to-5.4 eV; the highest occupied molecular orbital energy level of the main material is-6.0 eV to-5.4 eV; the highest occupied molecular orbital level of the material of the hole transport layer is-5.7 eV to-5.2 eV.
According to any of the preceding embodiments of the first aspect of the present application, the first carrier mobility of the host material and the carrier adjustment layer material is greater than or equal to 7 × 10-7cm2(vs), the second carrier mobility of the host material and the carrier adjusting layer material are both greater than or equal to 1 x 10-6cm2/vs。
According to any of the preceding embodiments of the first aspect of the present application, the first electrode is a cathode, the first carriers are electrons, the second electrode is an anode, and the second carriers are holes.
According to any one of the preceding embodiments of the first aspect of the present application, the lowest unoccupied molecular orbital level of the material of the carrier adjusting layer is greater than the lowest unoccupied molecular orbital level of the material of the first carrier functional layer and less than or equal to the lowest unoccupied molecular orbital level of the host material.
According to any one of the preceding embodiments of the first aspect of the present application, the first carrier functional layer comprises an electron transport layer, and the lowest unoccupied molecular orbital level of the material of the carrier adjusting layer is greater than the lowest unoccupied molecular orbital level of the material of the electron transport layer.
According to any one of the preceding embodiments of the first aspect of the present application, the lowest unoccupied molecular orbital level of the material of the carrier adjusting layer is between-3.0 eV and-2.6 eV; the lowest unoccupied molecular orbital level of the main material is-3.0 eV to-2.6 eV; the lowest unoccupied molecular orbital level of the material of the electron transport layer is-3.3 eV to-2.6 eV.
According to any of the preceding embodiments of the first aspect of the present application, the first carrier mobility of the host material and the carrier adjustment layer material is greater than or equal to 5 x 10-7cm2(vs) the second carrier mobility of the host material and the carrier adjusting layer material is greater than or equal to 1 x 10-5cm2/vs。
In a second aspect, an embodiment of the present application provides a display panel, including: a substrate; and a light emitting device layer on the substrate, the light emitting device layer including a plurality of light emitting devices arranged in an array, wherein at least a portion of the plurality of light emitting devices are the light emitting devices as described in any of the previous embodiments.
According to the foregoing embodiment of the second aspect of the present application, the plurality of light emitting devices includes a red light emitting device, a green light emitting device, and a blue light emitting device, and the green light emitting device is the light emitting device as described in any of the previous examples.
The embodiment of the application provides a light-emitting device and a display panel, the light-emitting device comprises a first electrode, a second electrode and a light-emitting layer, the first carrier mobility of a main material of the light-emitting layer is smaller than the second carrier mobility of the main material, a carrier adjusting layer is additionally arranged between the light-emitting layer and a first carrier function layer, the material of the carrier adjusting layer and the main material of the light-emitting layer are selected from the same color light-emitting main material group, the potential barrier between the carrier adjusting layer and the light-emitting layer is lower, the first carrier can enter the light-emitting layer more easily through the carrier adjusting layer, the concentration of the first carrier injected into the light-emitting layer can be further improved, the exciton concentration in the light-emitting layer is increased, and the light-emitting efficiency of the light-emitting device is improved.
Drawings
Other features, objects, and advantages of the present application will become apparent from the following detailed description of non-limiting embodiments thereof, when read in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof, and which are not to scale.
Fig. 1 is a schematic structural diagram of a light emitting device according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a light-emitting device according to another embodiment of the present application;
fig. 3 is a schematic structural diagram of a light-emitting device according to still another embodiment of the present application;
fig. 4 is a graph of luminance-efficiency detection of green light emitting devices corresponding to comparative example and experimental example;
fig. 5 is a schematic structural diagram of a display panel according to an embodiment of the present application.
Description of reference numerals:
10-a light emitting device;
110-a first electrode;
120-a light emitting structure layer; 121-a first carrier functional layer; 121 a-first carrier injection layer; 121 b-first carrier transport layer; 121c — a second carrier blocking layer; 122-carrier adjusting layer; 123-a light emitting layer; 124-a second carrier functional layer; 124 a-second carrier injection layer; 124 b-second carrier transport layer; 124 c-first carrier blocking layer;
130-a second electrode;
20-a substrate;
30-drive the array layer.
Detailed Description
Features and exemplary embodiments of various aspects of the present application will be described in detail below, and in order to make objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. It will be apparent to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating examples thereof.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
It will be understood that when a layer, region or layer is referred to as being "on" or "over" another layer, region or layer in describing the structure of the component, it can be directly on the other layer, region or layer or intervening layers or regions may also be present. Also, if the component is turned over, one layer or region may be "under" or "beneath" another layer or region.
An Organic Light-Emitting Diode (OLED) is an electroluminescent device based on Organic materials, and its basic structure includes an anode, a cathode and a Light-Emitting layer, when a voltage is applied to the anode and the cathode, under the action of an electric field, holes and electrons are injected from the anode and the cathode, respectively, and are transmitted to the Light-Emitting layer, and when the two meet at the Light-Emitting layer, they combine to generate excitons, exciting the Light-Emitting molecules to generate visible Light.
In the OLED display panel, in order to improve product competitiveness, device efficiency needs to be further improved, and product power consumption needs to be reduced. However, in the existing OLED display panel, due to the fact that the transmission rates of the light-emitting host material to electrons and holes are different, the problem that the holes and electrons are not balanced after the light-emitting host material is doped with the guest material exists, and therefore the exciton concentration in the light-emitting layer is low, the device efficiency is low, and the product power consumption is high.
In order to solve the above problems, embodiments of the light emitting device and the display panel are provided, and the following description will be made with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a light emitting device according to an embodiment of the present application.
The embodiment provides a light emitting device 10 including a first electrode 110, a second electrode 130, and a light emitting structure layer 120 between the first electrode 110 and the second electrode 130.
The light emitting structure layer 120 includes a light emitting layer 123, a first carrier function layer 121, and a carrier adjusting layer 122. The first carrier function layer 121 is located between the first electrode 110 and the light emitting layer 123, and the carrier adjusting layer 122 is located between the light emitting layer 123 and the first carrier function layer 121. Under the action of the applied electric field, first carriers are injected from the first electrode 110 into the first carrier functional layer 121 and transported toward the light emitting layer 123, and second carriers are injected from the second electrode 130 and transported toward the light emitting layer 123. The light emitting layer 123 includes a host material and a guest material, and a first carrier mobility of the host material is smaller than a second carrier mobility of the host material. The material of the carrier adjusting layer 122 and the host material are both selected from the same color light emitting host material group.
It is understood that the material of the light emitting layer 123 of the light emitting device generally includes a host material and a guest material, the host material mainly transfers energy to the guest to make the guest emit light, and the guest material is used for determining the light emitting color.
One of the first electrode 110 and the second electrode 130 is an anode and the other is a cathode, and one of the first carrier and the second carrier is a hole and the other is an electron. When the first electrode 110 is an anode, the second electrode 130 is a cathode, the first carriers are holes injected from the anode, and the second carriers are electrons injected from the cathode.
The light emitting device 10 includes a plurality of light emitting devices having different emission colors, and the light emitting device 10 may be a red light emitting device, a green light emitting device, or a blue light emitting device. It is understood that the light emitting color of the light emitting device 10 depends on the light emitting color of the light emitting layer 123, and if the light emitting device 10 is a green light emitting device, the host material of the light emitting layer 123 is selected from the group of green light emitting host materials, and if the light emitting device 10 is a red light emitting device, the host material of the light emitting layer 123 is selected from the group of red light emitting host materials.
According to the light emitting device 10 provided in the embodiment of the present application, under the condition that the first carrier mobility of the host material of the light emitting layer is smaller than the second carrier mobility of the host material, the carrier adjusting layer 122 is disposed between the light emitting layer 123 and the first carrier functional layer 121, and since the material of the carrier adjusting layer 122 and the host material of the light emitting layer 123 are both selected from the same color light emitting host material group, the potential barrier between the carrier adjusting layer 122 and the light emitting layer 123 is low, the first carrier can enter the light emitting layer 123 more easily through the carrier adjusting layer 122, and then the concentration of the first carrier injected into the light emitting layer 123 can be increased, the concentration of excitons in the light emitting layer 123 is increased, and the light emitting efficiency of the light emitting device 10 is improved.
The host material of the light-emitting layer 123 may be one of the light-emitting host materials of the same color, or may be a mixture of two or more of the light-emitting host materials of the same color. The same color light emitting host material can be a host material suitable for red light or a host material suitable for green light or a host material suitable for blue light.
In some alternative embodiments, the same color light emitting host material group includes a first sub-host material and a second sub-host material, the host material of the light emitting layer 123 may include a first sub-host material and a second sub-host material, and a first carrier mobility of the first sub-host material may be smaller than a second carrier mobility of the first sub-host material, and a first carrier mobility of the second sub-host material may be larger than the second carrier mobility of the second sub-host material. The first sub-host material and the second sub-host material are two different materials in the same color light-emitting host material.
The main material of the light-emitting layer 123 adopts two different materials in the light-emitting main material with the same color, and the two different materials in the light-emitting main material with the same color are different carrier transport type materials, so that an exciton recombination region can be adjusted to the middle of the light-emitting layer 123, the deviation of the exciton recombination region is reduced, the service life of the device can be prolonged, the balance of hole electrons can be improved, and the efficiency of the device can be optimized.
When the host material of the light-emitting layer 123 is two or more different materials in the light-emitting host material with the same color, the material of the carrier adjusting layer 122 may be two or more different materials in the light-emitting host material with the same color, or may be one material in the light-emitting host material with the same color, which is not specifically limited in the present application.
In some alternative embodiments, the first carrier mobility of the material of the carrier adjusting layer 122 may be smaller than the second carrier mobility of the host material of the light emitting layer 123, which is more favorable for the balance of hole electrons in the light emitting layer 123.
Alternatively, to facilitate the screening of materials and thus the fabrication of the light emitting device 10, the material of the carrier adjusting layer 122 and the host material may be completely the same.
In other alternative embodiments, the material of the carrier adjusting layer 122 and the host material may not be completely the same, the material of the carrier adjusting layer 122 may be selected from one of the light emitting host materials of the same color, the light emitting host material and the host material of the light emitting layer 123 belong to the same color light emitting host material group, and the first carrier mobility of the material of the carrier adjusting layer 122 may be greater than the second carrier mobility of the material of the carrier adjusting layer 122, which is more favorable for the balance of hole electrons in the light emitting layer 123.
It is understood that when the first electrode 110 is an anode, the second electrode 130 is a cathode, the first carriers are holes injected from the anode, and the second carriers are electrons injected from the cathode, the hole mobility of the material of the carrier adjusting layer 122 is greater than the electron mobility; when the first electrode 110 is a cathode, the second electrode 130 is an anode, the first carriers are electrons injected from the cathode, and the second carriers are holes injected from the anode, the electron mobility of the material of the carrier adjusting layer 122 is greater than the hole mobility.
Optionally, when the host material includes a first sub-host material and a second sub-host material, the material of the carrier adjusting layer 122 may be the second sub-host material, so as to facilitate the screening of the materials. Of course, the material of the carrier adjusting layer 122 may also be a third sub-host material, the third sub-host material is different from the first sub-host material and the second sub-host material, the third sub-host material, the first sub-host material and the second sub-host material all belong to the same color light emitting host material group, and the first carrier mobility of the third sub-host material is greater than the second carrier mobility of the third sub-host material, which is also within the protection scope of the present application.
Note that the thicknesses of the carrier adjusting layer 122 and the light emitting layer 123 are not particularly limited in the present application. In some alternative embodiments, the thickness of the carrier adjusting layer 122 may be set according to the thickness of the light emitting layer 123. Alternatively, the ratio of the thickness of the carrier adjusting layer 122 to the thickness of the light emitting layer 123 may be set to 1:15 to 1: 3.
compared with the light-emitting layer 123 of the existing light-emitting device 10, the light-emitting device 10 provided by the embodiment of the application can reduce the thickness of the light-emitting layer 123 by 5nm to 10nm, so that the working voltage of the light-emitting device 10 can be reduced. Alternatively, the thickness of the carrier adjusting layer 122 may coincide with the reduced thickness of the light emitting layer 123.
Alternatively, the thickness of the carrier adjusting layer 122 may be 5nm to 10 nm. Alternatively, the thickness of the light emitting layer 123 may be 30nm to 45 nm.
Fig. 2 is a schematic structural diagram of a light emitting device according to another embodiment of the present application.
The specific structure of the first carrier function layer 121 is various, and the present application does not specifically limit this. It is understood that the first carrier function layer 121 may include any one of the first carrier injection layer 121a, the first carrier transport layer 121b, and the second carrier blocking layer 121 c. The first carrier injection layer 121a helps to lower a first carrier injection barrier from the first electrode 110 to the first carrier transport layer, increases the first carrier injection, enables the first carriers to be efficiently injected from the first electrode 110 into the first carrier transport layer 121b, the first carrier transport layer 121b is responsible for transporting the first carriers to the light emitting layer 123, and the second carrier blocking layer 121c is capable of blocking the second carriers from the second electrode 130 at the interface of the light emitting layer 123 of the light emitting device.
Alternatively, the first carrier function layer 121 may include a first carrier transport layer 121b, and the carrier adjusting layer 122 may be located between the first carrier transport layer 121b and the light emitting layer 123; so that when a voltage is applied to the first electrode 110 and the second electrode 130, the first carriers injected from the first electrode 110 migrate to the carrier adjusting layer 122 through the first carrier transporting layer 121b and then migrate to the light emitting layer 123 through the carrier adjusting layer 122.
Fig. 3 is a schematic structural diagram of a light emitting device according to still another embodiment of the present application.
In some alternative embodiments, the light emitting structure layer 120 may include a second carrier function layer 124, the second carrier function layer 124 being located between the second electrode 130 and the light emitting layer 123; when a voltage is applied to the first electrode 110 and the second electrode 130, second carriers are injected from the second electrode 130 to the second carrier functional layer 124 and migrate to the light emitting layer 123 through the second carrier functional layer 124.
The specific structure of the second carrier functional layer 124 is various, and the present application does not specifically limit this. It is understood that the second carrier function layer 124 may include any one of the second carrier injection layer 124a, the second carrier transport layer 124b, and the first carrier blocking layer 124 c. The second carrier injection layer 124a helps to lower a second carrier injection barrier from the second electrode 130 to the second carrier transport layer, and the increase in the second carrier injection enables the second carriers to be efficiently injected from the second electrode 130 into the second carrier transport layer 124b light emitting device, the second carrier transport layer 124b is responsible for transporting the second carriers to the light emitting layer 123, and the first carrier blocking layer 124c is capable of blocking the first carriers from the first electrode 110 at the light emitting layer 123 interface of the device.
In the light emitting device 10 provided in the embodiment of the present application, one of the first electrode 110 and the second electrode 130 is an anode, and the other is a cathode. It is to be understood that, when the first electrode 110 is an anode and the second electrode 130 is a cathode, the first carriers are holes and the second carriers are electrons, the first carrier functional layer 121 may include any one of a hole injection layer, a hole transport layer, and an electron blocking layer, and the second carrier functional layer 124 may include any one of an electron injection layer, an electron transport layer, and a hole blocking layer. When the first electrode 110 is a cathode and the second electrode 130 is an anode, the first carrier is an electron and the second carrier is a hole, the first carrier functional layer 121 may include any one of an electron injection layer, an electron transport layer, and a hole blocking layer, and the second carrier functional layer 124 may include any one of a hole injection layer, a hole transport layer, and an electron blocking layer.
In some alternative embodiments, the first electrode 110 may be an anode, the first carrier is a hole injected from the anode, the second electrode 130 may be a cathode, the second carrier is an electron injected from the cathode, the hole mobility of the host material of the light emitting layer 123 is smaller than the electron mobility of the host material, the first carrier functional layer 121 is located between the anode and the carrier adjusting layer 122, and the carrier adjusting layer 122 is located between the light emitting layer 123 and the first carrier functional layer 121.
The carrier adjusting layer 122 is disposed between the light emitting layer 123 and the anode, and holes can easily enter the light emitting layer 123 through the carrier adjusting layer, so that the concentration of the holes in the light emitting layer 123 is increased, the concentration of excitons in the light emitting layer 123 can be increased, and the light emitting efficiency of the light emitting device 10 is improved.
It is understood that, when the carrier adjusting layer 122 is not provided, since the hole mobility of the host material is smaller than the electron mobility of the host material, and the hole concentration in the light emitting layer 123 is low after the host material is mixed with the doping guest material, the exciton recombination region of the light emitting device 10 may be shifted toward the anode side, resulting in low efficiency of the light emitting device 10.
Alternatively, when the host material of the light emitting layer 123 and the carrier adjusting layer 122 material are screened, the hole mobility of both the host material and the carrier adjusting layer 122 material may be greater than or equal to 7 × 10-7cm2(vs), the electron mobility of the host material and the material of the carrier adjusting layer 122 may each be greater than or equal to 1 × 10-6cm2Vs to ensure the luminous efficiency of the light emitting device 10.
In some alternative embodiments, in the case where the first carrier function layer 121 is disposed between the anode and the carrier adjustment layer 122, a Highest Occupied Molecular Orbital (HOMO) energy level of the material of the carrier adjustment layer 122 may be less than a HOMO energy level of the material of the first carrier function layer 121 and greater than or equal to a HOMO energy level of the host material; the carrier adjusting layer 122 is arranged to adjust the HOMO level matching of the first carrier functional layer 121 and the light emitting layer 123, so that an energy level difference is formed among the host materials of the first carrier functional layer 121, the carrier adjusting layer 122 and the light emitting layer 123, and holes can be more easily transferred from the first carrier functional layer 121 to the light emitting layer 123, so that the concentration of the holes injected into the light emitting layer 123 can be increased, and the light emitting efficiency of the light emitting device 10 is improved.
Alternatively, the HOMO level of the material of the carrier adjusting layer 122 may be between-6.0 eV to-5.4 eV; the host material has a HOMO energy level between-6.0 eV and-5.4 eV.
Alternatively, the first carrier function layer 121 includes a hole transport layer, the carrier adjusting layer 122 is located between the hole transport layer and the light emitting layer 123, and the HOMO level of the material of the carrier adjusting layer 122 may be smaller than the HOMO level of the material of the hole transport layer first carrier transport layer 121 b.
Alternatively, the HOMO level of the material of the hole transport layer may be between-5.7 eV and-5.2 eV.
Fig. 4 is a graph showing luminance-efficiency measurements of green light-emitting devices corresponding to comparative and experimental examples.
In order to verify the practical effect of the design, the following first comparative example, first experimental example and second experimental example are designed: the green light emitting devices of the first comparative example, the first experimental example, and the second experimental example are all green light emitting devices, and hole mobility of a host material of the light emitting layer 123 is smaller than electron mobility of the host material of the light emitting layer 123, the green light emitting device of the first comparative example does not include the carrier adjusting layer 122, the green light emitting devices of the first and the second experimental examples include the carrier adjusting layer 122, and a material of the carrier adjusting layer 122 is completely the same as that of the host material of the light emitting layer 123, a thickness of the light emitting layer 123 in the green light emitting device of the first experimental example is smaller than that of the light emitting layer 123 in the green light emitting device of the first comparative example, and a thickness of the light emitting layer 123 in the green light emitting device of the second experimental example is equal to that of the light emitting layer 123 in the green light emitting device of the first comparative example. Efficiency tests are respectively carried out on the green light-emitting devices corresponding to the first comparative example, the first experimental example and the second experimental example, the test results are shown in fig. 4, and it can be seen from fig. 4 that compared with the first comparative example, the luminous efficiencies of the first experimental example and the second experimental example are both improved; compared with the second experimental example, since the thickness of the light emitting layer 123 in the green light emitting device of the first experimental example is smaller, that is, the thickness of the light emitting layer 123 doped with the guest material is reduced, the operating voltage of the light emitting device can be reduced, and thus the light emitting efficiency of the light emitting device is higher at the same operating voltage.
In other alternative embodiments, the first electrode 110 may be a cathode, the first carriers are electrons injected from the cathode, the second electrode 130 may be an anode, the second carriers are holes injected from the anode, the electron mobility of the host material is smaller than the hole mobility of the host material, and the carrier adjusting layer 122 is located between the light emitting layer 123 and the first carrier functional layer 121.
The carrier adjusting layer 122 is provided between the light emitting layer 123 and the cathode, and electrons can more easily enter the light emitting layer 123 through the carrier adjusting layer, so that the concentration of electrons in the light emitting layer 123 is increased, the concentration of excitons in the light emitting layer 123 can be increased, and the light emitting efficiency of the light emitting device 10 is improved.
It is understood that, when the carrier adjusting layer 122 is not provided, since the electron mobility of the host material is smaller than the hole mobility of the host material, and the doping guest material in the host material is mixed, the electron concentration in the light emitting layer 123 is low, and the exciton recombination region of the light emitting device 10 is shifted to the cathode side, resulting in low efficiency of the light emitting device 10.
Alternatively, when the host material of the light emitting layer 123 and the material of the carrier adjusting layer 122 are screened, electron mobility in both the host material and the material of the carrier adjusting layer 122 may be greater than or equal to 5 × 10-7cm2(vs), the hole mobilities of the host material and the material of the carrier-adjusting layer 122 may both be greater than or equal to 1 × 10-5cm2Vs to ensure the luminous efficiency of the light emitting device 10.
In some alternative embodiments, in the case where the first carrier functional layer 121 is disposed between the cathode and the carrier-adjusting layer 122, a Lowest Unoccupied Molecular Orbital (LUMO) energy level of the material of the carrier-adjusting layer 122 may be greater than a LUMO energy level of the material of the first carrier functional layer 121 and less than or equal to a LUMO energy level of the host material; the carrier adjusting layer 122 is arranged to adjust LUMO energy level matching of the first carrier functional layer 121 and the light emitting layer 123, so that an energy level difference is formed among the host materials of the first carrier functional layer 121, the carrier adjusting layer 122 and the light emitting layer 123, electrons can be more easily transferred from the first carrier functional layer 121 to the light emitting layer 123, the concentration of electrons injected into the light emitting layer 123 can be further improved, and the light emitting efficiency of the light emitting device 10 is improved.
Alternatively, the LUMO level of the material of the carrier adjustment layer 122 may be between-3.0 eV to-2.6 eV; the LUMO energy level of the host material is between-3.0 eV and-2.6 eV.
Alternatively, the first carrier function layer 121 includes an electron transport layer, the carrier adjusting layer 122 is located between the electron transport layer and the light emitting layer 123, and a LUMO level of a material of the carrier adjusting layer 122 may be greater than a LUMO level of a material of the electron transport layer.
Alternatively, the LUMO level of the material of the electron transport layer may be between-3.3 eV and-2.6 eV.
The embodiment of the application also provides a display panel. It is understood that the display panel may be an Organic Light Emitting Diode (OLED) display panel. Fig. 5 is a schematic structural diagram of a display panel according to an embodiment of the present application.
As shown in fig. 5, the display panel provided in the embodiment of the present application includes a substrate 20 and a light emitting device layer. The light emitting device layer is located on the substrate 20, and the light emitting device layer includes a plurality of light emitting devices 10 arranged in an array, wherein at least some of the plurality of light emitting devices 10 are the light emitting devices 10 according to any of the above embodiments.
Alternatively, the substrate 20 may be a substrate 20 made of glass, and in some embodiments, may also be a substrate 20 made of Polyimide (PI) material or a material containing PI, such that the substrate 20 may be bendable.
In some alternative embodiments, the light emitting device layer may include red light emitting devices, green light emitting devices, and blue light emitting devices arranged in an array, and the red light emitting devices, the green light emitting devices, and the blue light emitting devices may all adopt the structure of the light emitting device 10 of any of the above embodiments.
Optionally, the display panel further includes a driving array layer 30 located between the substrate 20 and the light emitting device layer, and the driving array layer 30 includes a plurality of pixel circuits arranged in an array, each pixel circuit being electrically connected to a corresponding light emitting device 10 to drive the corresponding light emitting device 10 to emit light.
In accordance with the embodiments of the present application as described above, these embodiments are not exhaustive and do not limit the application to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the application and its practical application, to thereby enable others skilled in the art to best utilize the application and its various modifications as are suited to the particular use contemplated. The application is limited only by the claims and their full scope and equivalents.

Claims (10)

1. A light emitting device comprising a first electrode, a second electrode, and a light emitting structure layer between the first electrode and the second electrode, the light emitting structure layer comprising:
a light emitting layer including a host material and a guest material, a first carrier mobility of the host material being smaller than a second carrier mobility of the host material;
a first carrier functional layer between the first electrode and the light emitting layer; and
and the carrier adjusting layer is positioned between the light emitting layer and the first carrier functional layer, and the main body material and the carrier adjusting layer are both selected from the same color light emitting main body material group.
2. The light-emitting device according to claim 1, wherein a material of the carrier adjustment layer is completely the same as the host material.
3. The light-emitting device according to claim 1, wherein the body material includes a first sub-body material and a second sub-body material, a first carrier mobility of the first sub-body material is smaller than a second carrier mobility of the first sub-body material, and the first carrier mobility of the second sub-body material is larger than the second carrier mobility of the second sub-body material;
preferably, the material of the carrier adjustment layer is the second sub-host material; or
The same-color light-emitting main body material group comprises a third sub-main body material, the carrier adjusting layer is made of the third sub-main body material, and the first carrier mobility of the third sub-main body material is larger than the second carrier mobility of the third sub-main body material.
4. The light-emitting device according to claim 1, wherein a thickness ratio of the carrier adjusting layer to the light-emitting layer is 1:15 to 1: 3;
preferably, the thickness of the carrier adjusting layer is 5 to 10nm, and the thickness of the light emitting layer is 30 to 45 nm.
5. The light-emitting device according to claim 1, wherein the first electrode is an anode, the first carriers are holes, the second electrode is a cathode, and the second carriers are electrons;
preferably, the highest occupied molecular orbital level of the material of the carrier regulation layer is smaller than the highest occupied molecular orbital level of the material of the first carrier functional layer and is greater than or equal to the highest occupied molecular orbital level of the host material.
6. The light-emitting device according to claim 5, wherein the first carrier functional layer comprises a hole transport layer, and a highest occupied molecular orbital level of a material of the carrier adjustment layer is smaller than a highest occupied molecular orbital level of a material of the hole transport layer;
preferably, the highest occupied molecular orbital level of the material of the carrier adjustment layer is-6.0 eV to-5.4 eV; the highest occupied molecular orbital energy level of the main body material is-6.0 eV to-5.4 eV; the highest occupied molecular orbital level of the material of the hole transport layer is-5.7 eV to-5.2 eV.
7. The light-emitting device according to claim 5, wherein the first carrier mobility of each of the host material and the carrier adjustment layer material is greater than or equal to 7 x 10-7cm2(vs), the second carrier mobility of the host material and the carrier adjusting layer material are both greater than or equal to 1 x 10-6cm2/vs。
8. The light-emitting device according to claim 1, wherein the first electrode is a cathode, the first carriers are electrons, the second electrode is an anode, and the second carriers are holes;
preferably, a lowest unoccupied molecular orbital level of a material of the carrier regulation layer is greater than a lowest unoccupied molecular orbital level of a material of the first carrier functional layer and is less than or equal to a lowest unoccupied molecular orbital level of the host material.
9. The light-emitting device according to claim 8, wherein the first carrier functional layer comprises an electron transport layer, and wherein a lowest unoccupied molecular orbital level of a material of the carrier adjustment layer is larger than a lowest unoccupied molecular orbital level of a material of the electron transport layer;
preferably, the lowest unoccupied molecular orbital level of the material of the carrier adjustment layer is-3.0 eV to-2.6 eV; the lowest unoccupied molecular orbital level of the main material is-3.0 eV to-2.6 eV; the lowest unoccupied molecular orbital level of the material of the electron transport layer is-3.3 eV to-2.6 eV;
preferably, the first carrier mobility of the host material and the carrier adjusting layer material is greater than or equal to 5 × 10-7cm2(vi) a second carrier mobility of the host material and the carrier adjusting layer material is greater than or equal to 1 x 10-5cm2/vs。
10. A display panel, comprising:
a substrate; and
a light emitting device layer on the substrate, the light emitting device layer comprising a plurality of light emitting devices arranged in an array, wherein at least a portion of the plurality of light emitting devices are light emitting devices according to any one of claims 1 to 9;
preferably, the plurality of light emitting devices include a red light emitting device, a green light emitting device, and a blue light emitting device, the green light emitting device being the light emitting device according to any one of claims 1 to 9.
CN202110683506.7A 2021-06-21 2021-06-21 Light emitting device and display panel Active CN113437230B (en)

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