Light-emitting device, display panel, and electronic device

Abstract

Provided are a light-emitting device, a display panel, and an electronic device. The light-emitting device comprises: an anode; a first light-emitting unit located on the anode and comprising a first light-emitting layer; and a second light-emitting unit located on the side of the first light-emitting unit away from the anode and comprising a second light-emitting layer. The first light-emitting layer and the second light-emitting layer emit light of the same color, the distance between the anode and the first light-emitting layer is a first distance, the distance between the first light-emitting layer and the second light-emitting layer is a second distance, and the first distance is greater than or equal to the second distance.

Description

Light-emitting devices, display panels, electronic devices Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a light-emitting device and a display panel and an electronic device including the light-emitting device. Background Art

[0002] In recent years, organic light-emitting diode (OLED) displays (OLEDs) have attracted increasing attention as a new type of display. Due to their advantages such as self-luminescence, high brightness, high resolution, wide viewing angle, fast response time, high contrast, low energy consumption, and flexibility, they have become a highly sought-after display product in the market. However, with the continuous development of OLED products, the requirements for the lifespan and power consumption of OLED displays are becoming increasingly stringent.

[0003] Summary of the Invention

[0004] According to one aspect of the present disclosure, a light-emitting device is provided, comprising: an anode; a first light-emitting unit located on the anode and comprising a first light-emitting layer; and a second light-emitting unit located on a side of the first light-emitting unit away from the anode and comprising a second light-emitting layer. The first light-emitting layer and the second light-emitting layer emit light of the same color, the anode and the first light-emitting layer are separated by a first distance, the first light-emitting layer and the second light-emitting layer are separated by a second distance, and the first distance is greater than or equal to the second distance.

[0005] In some embodiments, the light emitting device further comprises a charge generation layer located between the first light emitting unit and the second light emitting unit, wherein the charge generation layer comprises an N-type charge generation layer and a P-type charge generation layer, wherein the N-type charge generation layer is closer to the first light emitting unit than the P-type charge generation layer.

[0006] In some embodiments, the first light-emitting unit further includes a first hole transport layer located between the anode and the first light-emitting layer, and the second light-emitting unit further includes a second hole transport layer located between the P-type charge generation layer and the second light-emitting layer, and the sum of the thicknesses of the N-type charge generation layer, the P-type charge generation layer, and the second hole transport layer is less than the thickness of the first hole transport layer.

[0007] In some embodiments, the first light-emitting unit further includes a first optical auxiliary layer located between the first hole transport layer and the first light-emitting layer, and the second light-emitting unit further includes a second optical auxiliary layer located between the second hole transport layer and the second light-emitting layer, and the thickness of the first optical auxiliary layer is greater than or equal to the thickness of the second optical auxiliary layer.

[0008] In some embodiments, the first light-emitting unit further includes: a hole injection layer located between the anode and the first light-emitting layer; a first electron transport layer located between the first light-emitting layer and the second light-emitting layer; and a first hole blocking layer located between the first electron transport layer and the first light-emitting layer.

[0009] In some embodiments, the hole injection layer and the P-type charge generation layer both include a host material and a guest material, the guest material of the hole injection layer is the same as the guest material of the P-type charge generation layer, and the first ratio of the mass of the guest material in the hole injection layer to the sum of the masses of the host material and the guest material is less than the second ratio of the mass of the guest material in the P-type charge generation layer to the sum of the masses of the host material and the guest material.

[0010] In some embodiments, the conductivity of the hole injection layer is less than the conductivity of the P-type charge generation layer.

[0011] In some embodiments, the thickness of the hole injection layer is less than or equal to the sum of the thickness of the first electron transport layer and the thickness of the first hole blocking layer; or the thickness of the hole injection layer is greater than the sum of the thickness of the first electron transport layer and the thickness of the first hole blocking layer.

[0012] In some embodiments, the light emitting device further comprises a cathode located on a side of the second light emitting unit away from the anode. The distance between the second light emitting layer and the cathode is a third distance, and the first distance is greater than or equal to the third distance.

[0013] In some embodiments, the third distance is greater than or equal to the second distance.

[0014] In some embodiments, the distance between the second light-emitting layer and the anode is a fourth distance, the distance between the anode and the cathode is a fifth distance, and a ratio of the fourth distance to the fifth distance is 70% to 85%.

[0015] In some embodiments, the distance between the anode and the cathode is a fifth distance, and a ratio of the first distance to the fifth distance is 36% to 50%.

[0016] In some embodiments, the distance between the anode and the cathode is the fifth distance, the first light-emitting layer and the second light-emitting layer both emit red light, and the ratio of the second distance to the fifth distance is 20% to 30%; or the first light-emitting layer and the second light-emitting layer both emit green light, and the ratio of the second distance to the fifth distance is 25% to 35%; or the first light-emitting layer and the second light-emitting layer both emit blue light, and the ratio of the second distance to the fifth distance is 31% to 45%.

[0017] In some embodiments, the second light-emitting unit further includes: an electron injection layer located between the cathode and the second light-emitting layer; a second electron transport layer located between the electron injection layer and the second light-emitting layer; and a second hole blocking layer located between the second electron transport layer and the second light-emitting layer.

[0018] In some embodiments, the first light-emitting unit further includes a third light-emitting layer and a fifth light-emitting layer, the first light-emitting layer, the third light-emitting layer, and the fifth light-emitting layer being separated from each other and emitting light of different colors, the second light-emitting unit further includes a fourth light-emitting layer and a sixth light-emitting layer, the second light-emitting layer, the fourth light-emitting layer, and the sixth light-emitting layer being separated from each other and emitting light of different colors, the first light-emitting layer and the second light-emitting layer emitting light of a first color, and their orthographic projections on the anode at least partially overlap, the third light-emitting layer and the fourth light-emitting layer emitting light of a second color, and their orthographic projections on the anode at least partially overlap, and the fifth light-emitting layer and the sixth light-emitting layer emitting light of a third color, and their orthographic projections on the anode at least partially overlap.

[0019] According to another aspect of the present disclosure, a light-emitting device is provided, comprising: an anode; a first light-emitting unit located on the anode and comprising a first light-emitting layer; a second light-emitting unit located on a side of the first light-emitting unit away from the anode and comprising a second light-emitting layer; and a cathode located on a side of the second light-emitting unit away from the anode. The first light-emitting layer and the second light-emitting layer emit light of the same color, the anode and the first light-emitting layer are separated by a first distance, the first light-emitting layer and the second light-emitting layer are separated by a second distance, and the second light-emitting layer and the cathode are separated by a third distance, the first distance being greater than or equal to the third distance, and the third distance being greater than or equal to the second distance.

[0020] According to another aspect of the present disclosure, a display panel is provided, comprising: a substrate; and a plurality of light-emitting devices as described in any one of the above embodiments, wherein the plurality of light-emitting devices are arranged on the substrate.

[0021] In some embodiments, the display panel further includes a plurality of isolation columns, the light-emitting device further includes a charge generation layer located between the first light-emitting unit and the second light-emitting unit, the charge generation layer is shared by the plurality of light-emitting devices, the plurality of isolation columns are located on one side of the substrate where the plurality of light-emitting devices are arranged, and at least a portion of the charge generation layer located between the plurality of light-emitting devices is separated by the plurality of isolation columns.

[0022] In some embodiments, the first light-emitting unit further includes a third light-emitting layer and a fifth light-emitting layer, the first light-emitting layer, the third light-emitting layer, and the fifth light-emitting layer are separated from each other and emit light of different colors; the second light-emitting unit further includes a fourth light-emitting layer and a sixth light-emitting layer, the second light-emitting layer, the fourth light-emitting layer, and the sixth light-emitting layer are separated from each other and emit light of different colors; the first light-emitting layer and the second light-emitting layer emit light of a first color and their orthographic projections on the anode at least partially overlap, the third light-emitting layer and the fourth light-emitting layer emit light of a second color and their orthographic projections on the anode at least partially overlap, the fifth light-emitting layer and The sixth light-emitting layer emits light of a third color and the orthographic projections of the two on the anode at least partially overlap; the light-emitting device includes a plurality of sub-light-emitting devices, and the sub-light-emitting devices include a first sub-light-emitting device, a second sub-light-emitting device and a third sub-light-emitting device, the first sub-light-emitting device includes the first light-emitting layer and the second light-emitting layer, the second sub-light-emitting device includes the third light-emitting layer and the fourth light-emitting layer, and the third sub-light-emitting device includes the fifth light-emitting layer and the sixth light-emitting layer; and the charge generation layer is also shared by the plurality of sub-light-emitting devices, and the portion of the charge generation layer located between the plurality of sub-light-emitting devices is also separated by the plurality of isolation columns.

[0023] In some embodiments, the light emitting device further comprises a cathode located on a side of the second light emitting unit away from the anode, the distance between the anode and the cathode is a fifth distance, and a ratio of the fifth distance to the thickness of the isolation column is 15% to 40%.

[0024] According to yet another aspect of the present disclosure, an electronic device is provided, comprising the display panel described in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Hereinafter, various exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings; in the accompanying drawings:

[0026] FIG1 shows a schematic structural diagram of a light emitting device according to an embodiment of the present disclosure;

[0027] FIG2 shows a schematic structural diagram of a light emitting device according to an embodiment of the present disclosure;

[0028] FIG3 shows a spectrum diagram of red light, green light, and blue light emitted by the light emitting device according to Comparative Example 1 of the present disclosure;

[0029] FIG4 shows a spectrum of green light emitted by a light-emitting device according to Comparative Example 2 of the present disclosure;

[0030] FIG5 shows a spectrum of red light emitted by the light-emitting device according to Comparative Example 2 of the present disclosure;

[0031] FIG6 shows a spectrum of blue light emitted by the light-emitting device according to Comparative Example 2 of the present disclosure;

[0032] FIG7 shows a schematic structural diagram of a light emitting device according to another embodiment of the present disclosure;

[0033] FIG8 shows a schematic structural diagram of a light emitting device according to a reference example;

[0034] FIG9 shows a schematic structural diagram of a display panel according to an embodiment of the present disclosure;

[0035] FIG10 shows a schematic planar layout diagram of isolation columns according to an embodiment of the present disclosure;

[0036] FIG11 is a schematic diagram showing a partial structure of the display panel of FIG9 ; and

[0037] FIG12 shows a block diagram of an electronic device according to an embodiment of the present disclosure.

[0038] It should be understood that the accompanying drawings are merely schematic illustrations of exemplary embodiments of the present disclosure and are not intended to limit the present disclosure and are not necessarily drawn to scale. In addition, in the accompanying drawings, identical or similar components are indicated by identical or similar reference numerals. DETAILED DESCRIPTION

[0039] The following will clearly describe the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0040] Organic light-emitting diode (OLED) displays have been widely used in mobile devices such as mobile phones and watches in recent years due to their numerous advantages. However, the short lifespan and low luminous efficiency of traditional OLED displays have limited their adoption in the display industry, particularly in medium and large-sized displays.

[0041] To improve the luminous efficiency and lifespan of OLED displays, two light-emitting layers emitting the same color can be connected in series through a charge generation unit to improve current efficiency. The light emitted by the two light-emitting layers forms a standing wave within the resonant cavity of the stacked organic light-emitting device. The standing wave consists of nodes and antinodes. A node refers to the point where the amplitude is the smallest in the standing wave, and an antinode refers to the point where the amplitude is the largest in the standing wave. To achieve maximum optical efficiency, traditional stacked organic light-emitting devices typically position the two light-emitting layers close to the antinodes of the standing wave. For example, the first of the two light-emitting layers is positioned close to the first antinode, and the second of the two light-emitting layers is positioned close to the second antinode. For top-emitting devices, the distance between the second antinode and the anode is much greater than the distance between the first antinode and the anode. To meet the above optical design requirements, the thickness of the second hole transport layer that transports holes to the second light-emitting layer needs to be much greater than the thickness of the first hole transport layer that transports holes to the first light-emitting layer. However, this design will seriously disrupt the charge balance within the traditional stacked organic light-emitting device, and charge balance within the device is a key factor in achieving high efficiency and long life for OLEDs. In addition, in traditional stacked organic light-emitting devices, the roughness of the anode and impurities introduced during the preparation process will affect the stability of the light-emitting device. The rougher the anode or the more impurities remain, the more likely it is to induce adverse phenomena such as leakage or breakdown in the device.

[0042] In view of this, embodiments of the present disclosure provide a light emitting device, which can solve at least one of the problems existing in the prior art.

[0043] Figure 1 shows a schematic structural diagram of a light-emitting device 100 according to an embodiment of the present disclosure. As shown in Figure 1 , light-emitting device 100 includes: an anode 101; a first light-emitting unit 102, located on anode 101 and including a first light-emitting layer 1021; and a second light-emitting unit 103, located on a side of the first light-emitting unit 102 away from anode 101 and including a second light-emitting layer 1031. First light-emitting layer 1021 and second light-emitting layer 1031 emit light of the same color. The distance between anode 101 and first light-emitting layer 1021 is a first distance d1, and the distance between first light-emitting layer 1021 and second light-emitting layer 1031 is a second distance d2. The first distance d1 is greater than or equal to the second distance d2.

[0044] The light-emitting device 100 can be called a stacked light-emitting device, which includes at least two light-emitting units stacked in the thickness direction, and the at least two light-emitting units emit light of the same color and are connected in series with each other. Compared with a light-emitting device including only a single light-emitting unit, the overall luminous efficiency and life of the stacked light-emitting device can be significantly improved. Stacked light-emitting devices can be widely used in display panels, automotive products, lighting and other fields. Since they can be applied to more special scenarios, there are usually higher requirements for the life, efficiency and stability of stacked light-emitting devices. The first light-emitting layer 1021 and the second light-emitting layer 1031 can be formed of various suitable materials, such as organic materials, inorganic materials, or doping of organic and inorganic materials. In some embodiments, the first light-emitting layer 1021 and the second light-emitting layer 1031 are both formed of organic materials. In such an embodiment, the light-emitting device 100 can be an organic light-emitting diode device.

[0045] As is well known, the thicker the organic material film, the longer the charge transfer path, and accordingly, the greater the barrier to charge transfer caused by traps. In the light-emitting device 100, the second distance d2 typically contains more film layers than the first distance d1. Therefore, charge injection within the second distance d2 is more difficult than within the first distance d1. If appropriate intervention is not taken, this can easily lead to unbalanced charge transfer between the first light-emitting unit 102 and the second light-emitting unit 103. In the embodiment of the present disclosure, by designing the first distance d1 to be greater than or equal to the second distance d2, on the one hand, the difficulty of charge injection within the range of the second distance d2 can be reduced, and the charge transfer capability in the second light-emitting unit 103 can be improved, thereby facilitating the balance of charge injection and transfer in the first light-emitting unit 102 and the second light-emitting unit 103, improving the problem of device performance degradation (especially device life) caused by charge imbalance, and maximizing the advantages of the stacked light-emitting device in improving life. On the other hand, designing the first distance d1 to be greater than or equal to the second distance d2 means that the anode 101 is farther away from the first light-emitting layer 1021. Therefore, the first light-emitting layer 1021 and the second light-emitting layer 1031 above the first light-emitting layer 1021 can be away from the anode 101. In this way, the effects of the roughness of the anode 101 and impurities that may be introduced during the preparation process on the luminescent characteristics of the first light-emitting layer 1021 and the second light-emitting layer 1031 can be reduced or even avoided, thereby improving the stability of the luminescent characteristics of the light-emitting device 100, thereby also helping to improve the luminous efficiency of the light-emitting device 100 and extend the service life of the light-emitting device 100.

[0046] For example, the first distance d1 may refer to the distance between the surface of the first light-emitting layer 1021 close to the anode 101 and the surface of the anode 101 close to the first light-emitting layer 1021. The second distance d2 may refer to the distance between the surface of the first light-emitting layer 1021 away from the anode 101 and the surface of the second light-emitting layer 1031 close to the anode 101.

[0047] As shown in FIG1 , the light-emitting device 100 may further include a charge generation layer 104 located between the first light-emitting unit 102 and the second light-emitting unit 103. The first light-emitting unit 102 and the second light-emitting unit 103 are connected in series via the charge generation layer 104, thereby doubling the current efficiency, which helps improve the brightness of the light-emitting device 100 and extend the service life of the light-emitting device 100. Furthermore, the charge generation layer 104 can also provide electrons to the first light-emitting unit 102 and holes to the second light-emitting unit 103, respectively, as will be described in detail later. The light-emitting device 100 also includes a cathode 105 located on the side of the second light-emitting unit 103 away from the anode 101.

[0048] The first light-emitting unit 102 may further include a first hole transport layer 1022 and a first electron transport layer 1023. The first hole transport layer 1022 transports holes provided by the anode 101 to the first light-emitting layer 1021, and the first electron transport layer 1023 transports electrons provided by the charge generation layer 104 to the first light-emitting layer 1021. The electrons and holes recombine to form excitons in the first light-emitting layer 1021, generating energy level transitions, thereby causing the first light-emitting layer 1021 to emit light.

[0049] The second light-emitting unit 103 may further include a second hole transport layer 1032 and a second electron transport layer 1033. The second hole transport layer 1032 transports holes provided by the charge generation layer 104 to the second light-emitting layer 1031, and the second electron transport layer 1033 transports electrons provided by the cathode 105 to the second light-emitting layer 1031. The electrons and holes recombine to form excitons in the second light-emitting layer 1031, generating energy level transitions, thereby causing the second light-emitting layer 1031 to emit light.

[0050] Figure 2 shows a more detailed structure of the light emitting device 100. In Figure 2, the distance between the anode 101 and the first light emitting layer 1021 is a first distance d1, and the distance between the first light emitting layer 1021 and the second light emitting layer 1031 is a second distance d2. The first distance d1 is greater than or equal to the second distance d2.

[0051] As shown in FIG2 , in some embodiments, the first light-emitting unit 102 may further include a hole injection layer 1024 located between the anode 101 and the first light-emitting layer 1021, and a first hole blocking layer 1025 located between the first electron transport layer 1023 and the first light-emitting layer 1021. The thickness T1 of the hole injection layer 1024 affects the ease with which holes are injected from the anode 101 into the first light-emitting layer 1021. The thicker the thickness T1 of the hole injection layer 1024, the more difficult it is for holes to be injected from the anode 101 into the first light-emitting layer 1021. However, if the thickness T1 of the hole injection layer 1024 is too thin, some negative effects may also occur. The thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023 affect the difficulty of injecting electrons from the charge generation layer 104 into the first light-emitting layer 1021. The thicker the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, the more difficult it is for electrons to be injected from the charge generation layer 104 into the first light-emitting layer 1021.

[0052] In some embodiments, the thickness T1 of the hole injection layer 1024 is less than or equal to the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023 , ie, T1≤T2+T3.

[0053] In some alternative embodiments, the thickness T1 of the hole injection layer 1024 is greater than the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, i.e., T1>T2+T3. By making the thickness T1 of the hole injection layer 1024 greater than the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, the thickness T1 of the hole injection layer 1024 is increased, making it more difficult for holes to be injected from the anode 101 into the first light-emitting layer 1021, thereby slowing the injection rate of holes into the first light-emitting unit 102. Those skilled in the art will appreciate that in conventional OLED light-emitting devices, the injection rate of holes is generally greater than the injection rate of electrons. In the light-emitting device 100, slowing the hole injection rate into the first light-emitting unit 102 facilitates the injection of holes and electrons into the first light-emitting layer 1021 at a relatively balanced rate, thereby effectively improving the injection balance of electrons and holes into the first light-emitting unit 102. The charge balance inside the device is a key factor in achieving high efficiency and long life of the device. Therefore, such a design is conducive to improving the luminous efficiency of the light-emitting device 100 and extending the service life of the light-emitting device 100.

[0054] In some embodiments, the charge generation layer 104 may include an N-type charge generation layer 1041 and a P-type charge generation layer 1042, wherein the N-type charge generation layer 1041 is closer to the first light-emitting unit 102 than the P-type charge generation layer 1042. The N-type charge generation layer 1041 can provide electrons for the first light-emitting unit 102, and the P-type charge generation layer 1042 can provide holes for the second light-emitting unit 103. The N-type charge generation layer 1041 and the P-type charge generation layer 1042 are in contact with each other to form a charge generation layer 104 having charge separation and transport functions.

[0055] As shown in FIG2 , the first hole transport layer 1022 of the first light-emitting unit 102 is located between the hole injection layer 1024 and the first light-emitting layer 1021, and the second hole transport layer 1032 of the second light-emitting unit 103 is located between the P-type charge generation layer 1042 and the second light-emitting layer 1031. The sum of the thickness T5 of the N-type charge generation layer 1041, the thickness T6 of the P-type charge generation layer 1042, and the thickness T7 of the second hole transport layer 1032 is less than the thickness T4 of the first hole transport layer 1022, i.e., T4>T5+T6+T7.

[0056] In conventional stacked light-emitting devices, the hole injection rate of the first light-emitting unit is generally greater than the hole injection rate of the second light-emitting unit, which can lead to a charge imbalance between the first and second light-emitting units. In the light-emitting device 100 provided in the embodiment of the present disclosure, the thickness T4 of the first hole transport layer 1022 affects the ease with which holes are injected from the anode 101 into the first light-emitting layer 1021. The greater the thickness T4 of the first hole transport layer 1022, the more difficult it is for holes to be injected into the first light-emitting layer 1021. The thickness T5 of the N-type charge generation layer 1041, the thickness T6 of the P-type charge generation layer 1042, and the thickness T7 of the second hole transport layer 1032 affect the ease with which holes are injected from the P-type charge generation layer 1042 into the second light-emitting layer 1031. The greater the value of T5+T6+T7, the more difficult it is for holes to be injected into the second light-emitting layer 1031. By ensuring that T4 is greater than T5+T6+T7, the hole injection rate in the first light-emitting unit 102 can be slowed, thereby promoting charge balance between the first light-emitting unit 102 and the second light-emitting unit 103. Furthermore, this design can also slow the hole injection rate within the second light-emitting unit 103 and accelerate the electron injection rate within the second light-emitting unit 103, thereby promoting electron-hole injection balance within the second light-emitting unit 103. Internal charge balance is a key factor in achieving high device efficiency and long life. Therefore, this design helps improve the luminous efficiency of the light-emitting device 100 and extend its service life.

[0057] Continuing with reference to FIG2 , in some embodiments, the first light-emitting unit 102 may further include a first optical auxiliary layer 1026 located between the first hole transport layer 1022 and the first light-emitting layer 1021, and the second light-emitting unit 103 may further include a second optical auxiliary layer 1036 located between the second hole transport layer 1032 and the second light-emitting layer 1031. The first optical auxiliary layer 1026 and the second optical auxiliary layer 1036 can reduce the hole injection barrier and adjust the optical microcavity length to better match the emission wavelength.

[0058] The thickness T9 of the first optical auxiliary layer 1026 is greater than or equal to the thickness T8 of the second optical auxiliary layer 1036. The thickness T9 of the first optical auxiliary layer 1026 affects the ease with which holes are injected from the anode 101 into the first light-emitting layer 1021. The greater the thickness T9 of the first optical auxiliary layer 1026, the more difficult it is for holes to be injected into the first light-emitting layer 1021. Similarly, the thickness T8 of the second optical auxiliary layer 1036 affects the ease with which holes are injected from the P-type charge generation layer 1042 into the second light-emitting layer 1031. The greater the thickness T8 of the second optical auxiliary layer 1036, the more difficult it is for holes to be injected into the second light-emitting layer 1031. As previously mentioned, in conventional stacked light-emitting devices, the hole injection rate of the first light-emitting unit is generally greater than the hole injection rate of the second light-emitting unit. In the light-emitting device 100 provided in the embodiment of the present disclosure, by ensuring that T9 ≥ T8, the hole injection rate in the first light-emitting unit 102 can be slowed compared to the second light-emitting unit 103, thereby helping to promote charge balance between the first light-emitting unit 102 and the second light-emitting unit 103. Furthermore, slowing the hole injection rate in the first light-emitting unit 102 helps further improve the injection ratio of electrons and holes in the first light-emitting layer 1021, thereby helping to further promote the injection balance of electrons and holes in the first light-emitting unit 102. Charge balance within a device is a key factor in achieving high efficiency and a long life. Therefore, this design is conducive to improving the luminous efficiency of the light-emitting device 100 and extending the service life of the light-emitting device 100.

[0059] As shown in FIG2 , in some embodiments, the second light-emitting unit 103 may further include an electron injection layer 1034 located between the cathode 105 and the second electron transport layer 1033, and a second hole blocking layer 1035 located between the second electron transport layer 1033 and the second light-emitting layer 1031. The electron injection layer 1034 and the second hole blocking layer 1035 facilitate the injection of electrons from the cathode 105 into the second light-emitting layer 1031.

[0060] The material of the hole injection layer 1024 can be various suitable materials. In some embodiments, the material of the hole injection layer 1024 can be a p-type dopant of a strong electron-withdrawing system and a dopant of a hole transport material, such as hexacyanohexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (abbreviated as F4TCNQ), 1,2,3-tris[(cyano)(4-cyano-2,3,5,,6-tetrafluorophenyl)methylene]cyclopropane, etc. The chemical structure of F4TCNQ is

[0061] The first hole transport layer 1022, the first optical auxiliary layer 1026, the second optical auxiliary layer 1036, and the P-type charge generation layer 1042 may include the same material. In some embodiments, the materials constituting these film layers may be aromatic amine materials, dimethylfluorene materials, or carbazole materials having hole transport properties, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviated as BAFLP), and the like. ), 4,4'-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as DFLDPBi), 4,4'-bis(9-carbazolyl)biphenyl (abbreviated as CBP), 9-phenyl-3-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviated as PCzPA), 4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (abbreviated as m-MTDATA), etc. The chemical structure of NPB is The chemical structure of m-MTDATA is

[0062] The first light-emitting layer 1021 and the second light-emitting layer 1031 can be a red light-emitting layer, a green light-emitting layer, or a blue light-emitting layer. The red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer can be made of one material or a mixture of two or more materials.

[0063] The material of the blue light-emitting layer can be selected from pyrene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, metal complexes, etc. For example, the material of the blue light-emitting layer can be N1,N6-di([1,1'-biphenyl]-2-yl)-N1,N6-di([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene (ADN for short), 2-methyl-9,10-di-2-naphthylanthracene (MADN for short), 2,5,8,11-tetra-tert-butylperylene (TBPe for short), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAVBi for short), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi for short), bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium (FIrpic for short), etc. In some embodiments, the material of the blue light-emitting layer is a dopant of a host material and a guest material. The host material and the guest material of the blue light-emitting layer can be various suitable materials. In one example, the host material of the blue light-emitting layer is BH, whose chemical formula is The guest material of the blue light-emitting layer is BD, and its chemical structure is

[0064] The material of the green light-emitting layer can be selected from coumarin dyes, quinacridone copper derivatives, polycyclic aromatic hydrocarbons, diamine anthracene derivatives, carbazole derivatives, metal complexes, etc. For example, the material of the green light-emitting layer can be coumarin 6 (abbreviated as C-6), coumarin 545T (abbreviated as C-525T), quinacridone copper (abbreviated as QA), N,N'-dimethylquinacridone (abbreviated as DMQA), 5,12-diphenylnaphthonaphthalene (abbreviated as DPT), N10,N10'-diphenyl-N10,N10'-diphthaloyl-9,9'-dianthracene-10,10'-diamine (abbreviated as BA-NPB), tris(8-hydroxyquinolinol)aluminum(III) (abbreviated as Alq3), tris(2-phenylpyridine)iridium (abbreviated as Ir(ppy)3), di(2-phenylpyridine)iridium acetylacetonate (abbreviated as Ir(ppy)2(acac)), etc. In some embodiments, the material of the green light emitting layer is a dopant of a host material and a guest material. The host material and the guest material of the green light emitting layer can be various suitable materials. In one example, the host material of the green light emitting layer is GH, whose chemical structure is The guest material of the green light-emitting layer is GD, whose chemical structure is Abbreviated as (Ir(ppy)3).

[0065] The material of the red light-emitting layer can be selected from the DCM series of materials, metal complexes, and the like. For example, the material of the red light-emitting layer can be 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminophenyl)-4H-pyran (DCM for short), 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-9-enyl)-4H-pyran (DCJTB for short), bis(1-phenylisoquinolinol)(acetylacetonato)iridium(III) (Ir(piq)2(acac) for short), platinum octaethylporphyrin (PtOEP for short), bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonato)iridium (Ir(btp)2(acac) for short), and the like. In some embodiments, the material of the red light-emitting layer is a dopant of a host material and a guest material. The host and guest materials of the red light-emitting layer can be various suitable materials. In one example, the host material of the red light-emitting layer is RH, whose chemical structure is The guest material of the red light-emitting layer is RD, whose chemical structure is Abbreviated as (Ir(piq)(acac)).

[0066] The first hole blocking layer 1025, the second hole blocking layer 1035, the first electron transport layer 1023, the second electron transport layer 1033, and the N-type charge generation layer 1041 are generally aromatic heterocyclic compounds. Aromatic heterocyclic compounds can be, for example, imidazole derivatives such as benzimidazole derivatives, imidazopyridine derivatives, benzimidazolephenanthridine derivatives, or azine derivatives such as pyrimidine derivatives and triazine derivatives, or compounds containing nitrogen-containing six-membered ring structures such as quinoline derivatives, isoquinoline derivatives, and phenanthroline derivatives (also including compounds having phosphine oxide-based substituents on the heterocyclic ring.) For example, the materials of the first hole blocking layer 1025, the second hole blocking layer 1035, the first electron transport layer 1023, the second electron transport layer 1033, and the N-type charge generation layer 1041 can be 2- (4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (abbreviated as TPBi), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1, 2,4-triazole (abbreviated as TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (abbreviated as p-EtTAZ), red phenanthroline (abbreviated as BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (abbreviated as BCP), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviated as BzOs), etc. The chemical structure of TPBi is The chemical structure of BCP is

[0067] The material of the electron injection layer 1034 is generally an alkali metal or a metal, such as LiF, Yb, Mg, Ca, or a compound thereof.

[0068] The material of the anode 101 includes, but is not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, compounds or mixtures thereof.

[0069] 2 , the distance between the second light-emitting layer 1031 and the cathode 105 is a third distance d3. For example, the third distance d3 may refer to the distance between the surface of the second light-emitting layer 1031 away from the anode 101 and the surface of the cathode 105 closer to the anode 101. In some embodiments, the first distance d1 is greater than or equal to the third distance d3.

[0070] As previously mentioned, the roughness of the anode 101 and the degree of impurity removal during the fabrication process both affect the stability of the light-emitting device 100 formed via the evaporation process. The higher the roughness of the anode 101, or the more residual impurities, the more likely it is to cause defects such as leakage or breakdown in the light-emitting device. Designing the first distance d1 to be greater than or equal to the third distance d3 means that the anode 101 is farther away from the first light-emitting layer 1021. Therefore, the first light-emitting layer 1021 and the second light-emitting layer 1031 located above the first light-emitting layer 1021 can be further away from the anode 101. This reduces or even eliminates the effects of the roughness of the anode 101 and residual impurities on the luminescence characteristics of the first and second light-emitting layers 1021, improving the stability of the luminescence characteristics of the light-emitting device 100. Furthermore, if the light-emitting device 100 is a top-emitting device, this structural design can also ensure the light color and efficiency of the top-emitting device. This, in turn, helps improve the luminous efficiency of the light-emitting device 100 and extend its service life, particularly at high temperatures.

[0071] Furthermore, in some embodiments, the first distance d1, the second distance d2, and the third distance d3 satisfy d1 ≥ d3 ≥ d2. This means that the distance between the first light-emitting layer 1021 and the anode 101 and the distance between the second light-emitting layer 1031 and the anode 101 are further increased. Therefore, the first light-emitting layer 1021 and the second light-emitting layer 1031 can be further away from the anode 101. This helps to further reduce or even avoid the impact of the roughness of the anode 101 and residual impurities on the luminescent properties of the first light-emitting layer 1021 and the second light-emitting layer 1031, thereby helping to further improve the luminous efficiency of the light-emitting device 100 and extend the service life of the light-emitting device 100, especially the high-temperature service life.

[0072] As shown in FIG2 , the distance between the second light-emitting layer 1031 and the anode 101 is a fourth distance d4, and the distance between the anode 101 and the cathode 105 is a fifth distance d5. For example, the fourth distance d4 may refer to the distance between the surface of the second light-emitting layer 1031 near the anode 101 and the surface of the anode 101 near the second light-emitting layer 1031, and the fifth distance d5 may refer to the distance between the surface of the anode 101 near the cathode 105 and the surface of the cathode 105 near the anode 101. In some embodiments, the ratio of the fourth distance d4 to the fifth distance d5 is 70% to 85%. For example, the ratio of the fourth distance d4 to the fifth distance d5 may be 70%, 75%, 80%, 85%, etc. By designing the value of d4 / d5 to be between 70% and 85%, the microcavity effect of the light-emitting device 100 can be maintained, the light color and efficiency gain of the light-emitting device 100 can be improved, the luminous efficiency of the light-emitting device 100 can be increased, and the service life of the light-emitting device 100, especially at high temperatures, can be extended.

[0073] In some embodiments, the ratio of the first distance d1 to the fifth distance d5 is 36% to 50%. For example, the ratio of the first distance d1 to the fifth distance d5 can be 36%, 43%, 50%, etc. By designing the value of d1 / d5 to be between 36% and 50%, the microcavity effect of the light-emitting device 100 can be ensured, the light color and efficiency gain of the light-emitting device 100 can be improved, the luminous efficiency of the light-emitting device 100 can be increased, and the service life of the light-emitting device 100, especially the high-temperature service life, can be extended.

[0074] In some embodiments, the light-emitting device 100 is a red light-emitting device, i.e., both the first light-emitting layer 1021 and the second light-emitting layer 1031 emit red light. In this case, the ratio of the second distance d2 to the fifth distance d5 is 20% to 30%. For example, the ratio of the second distance d2 to the fifth distance d5 can be 20%, 25%, 30%, etc. In some alternative embodiments, the light-emitting device 100 is a green light-emitting device, i.e., both the first light-emitting layer 1021 and the second light-emitting layer 1031 emit green light. In this case, the ratio of the second distance d2 to the fifth distance d5 is 25% to 35%. For example, the ratio of the second distance d2 to the fifth distance d5 can be 25%, 30%, 35%, etc. In yet other alternative embodiments, the light-emitting device 100 is a blue light-emitting device, i.e., both the first light-emitting layer 1021 and the second light-emitting layer 1031 emit blue light. In this case, the ratio of the second distance d2 to the fifth distance d5 is 31% to 45%. For example, the ratio of the second distance d2 to the fifth distance d5 can be 31%, 38%, 45%, etc. The ratio range of the second distance d2 to the fifth distance d5 varies slightly for light-emitting devices of different colors. Setting the above ratio ensures the microcavity effect of the light-emitting device 100, ensuring that the light-emitting device 100 has excellent light color and high efficiency gain, improving the luminous efficiency of the light-emitting device 100, and extending the service life of the light-emitting device 100, especially the high-temperature service life.

[0075] The following is a specific example to illustrate the above-discussed improvement in luminous efficiency and service life of a light-emitting device by optimizing film thickness. The example provides a red light-emitting device, a green light-emitting device, and a blue light-emitting device, with reference examples and comparative examples for each color light-emitting device.

[0076] First, the parameters of each film layer of the red light-emitting device, the green light-emitting device, and the blue light-emitting device are introduced.

[0077] Reference example blue light emitting device:

[0078] Anode: The material is ITO.

[0079] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. The chemical structures of m-MTDATA and F4TCNQ can be found in the previous description. m-MTDATA is the host material, and F4TCNQ is the guest material. The ratio of the guest material mass to the sum of the host and guest materials is 1%. The film thickness is 10nm.

[0080] The first hole transport layer: the material is m-MTDATA, and the film thickness is 18 nm.

[0081] The first optical auxiliary layer: the material is NPB, the film thickness is 5.5 nm, and the chemical structure of NPB can refer to the description above.

[0082] First luminescent layer (blue luminescent layer): The material is a mixture of BH and BD. The chemical structures of BH and BD can be found in the previous description. BH is the host material, BD is the guest material, and the ratio of the guest material mass to the sum of the host and guest materials is 5%. The film thickness is 20 nm.

[0083] The first hole blocking layer is made of TPBi with a thickness of 5 nm. The chemical structure of TPBi can be found in the previous description.

[0084] First electron transport layer: The material is a mixture of BCP and Liq, where Liq is lithium octahydroxyquinoline. The chemical structure of BCP can be found in the previous description. The mass ratio of BCP to Liq is 1:1, and the film thickness is 20nm.

[0085] N-type charge generation layer: the material is a mixture of BCP and Yb, BCP is the host material, Yb is the guest material, the ratio of the mass of the guest material to the sum of the masses of the host material and the guest material is 0.5%, and the film thickness is 18nm.

[0086] P-type charge generation layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 9nm.

[0087] The second hole transport layer: the material is m-MTDATA, and the film thickness is 14.5 nm.

[0088] The second optical auxiliary layer: the material is NPB, and the film thickness is 5nm.

[0089] Second emitting layer (blue emitting layer): Material is a mixture of BH and BD. BH is the host material, BD is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host material and the guest material is 5%, and the film thickness is 20nm.

[0090] The second hole blocking layer: the material is TPBi, and the film thickness is 5nm.

[0091] Second electron transport layer: The material is a mixture of BCP and Liq. The mass ratio of BCP to Liq is 1:1, and the film thickness is 30nm.

[0092] Electron injection layer: The material is Yb and the film thickness is 1nm.

[0093] Cathode: The material is a mixture of Mg and Ag, with a film thickness of 13nm.

[0094] Light extraction layer: The material is NPB, and the film thickness is 60nm.

[0095] Comparative Example 1 of Blue Light Emitting Device:

[0096] Compared to the blue light-emitting device of the reference example, except for the first hole transport layer, the first optical auxiliary layer, the second hole transport layer, and the second optical auxiliary layer, the parameters of the other film layers of the blue light-emitting device of Comparative Example 1 are the same as those of the corresponding film layers of the blue light-emitting device of the reference example. For the sake of brevity, only the parameters of the first hole transport layer, the first optical auxiliary layer, the second hole transport layer, and the second optical auxiliary layer of the blue light-emitting device of Comparative Example 1 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers of the blue light-emitting device of the reference example.

[0097] The first hole transport layer: the material is m-MTDATA, and the film thickness is 99 nm.

[0098] The first optical auxiliary layer: the material is NPB, and the film thickness is 7nm.

[0099] The second hole transport layer: the material is m-MTDATA, and the film thickness is 34 nm.

[0100] Second optical auxiliary layer: the material is NPB, and the film thickness is 7nm.

[0101] Comparative Example 2 of Blue Light Emitting Device:

[0102] Compared to the blue light-emitting device in comparative example 1, except for the hole injection layer, the parameters of the other film layers in the blue light-emitting device in comparative example 2 are the same as those of the corresponding film layers in the blue light-emitting device in comparative example 1. For the sake of brevity, only the parameters of the hole injection layer in the blue light-emitting device in comparative example 2 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers in the blue light-emitting device in comparative example 1.

[0103] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 10nm.

[0104] Reference example green light emitting device:

[0105] Anode: The material is ITO.

[0106] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 1%, and the film thickness is 10nm.

[0107] The first hole transport layer: the material is m-MTDATA, and the film thickness is 18 nm.

[0108] The first optical auxiliary layer: the material is NPB, and the film thickness is 14.5 nm.

[0109] First luminescent layer (green luminescent layer): The material is a mixture of GH and GD. The chemical structures of GH and GD can be found in the previous description. GH is the host material, GD is the guest material, and the ratio of the guest material mass to the sum of the host and guest materials is 8%. The film thickness is 33 nm.

[0110] The first hole blocking layer: the material is TPBi, and the film thickness is 5 nm.

[0111] First electron transport layer: The material is a mixture of BCP and Liq. The mass ratio of BCP to Liq is 1:1, and the film thickness is 20nm.

[0112] N-type charge generation layer: the material is a mixture of BCP and Yb, BCP is the host material, Yb is the guest material, the ratio of the mass of the guest material to the sum of the masses of the host material and the guest material is 0.5%, and the film thickness is 18nm.

[0113] P-type charge generation layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 9nm.

[0114] The second hole transport layer: the material is m-MTDATA, and the film thickness is 14.5 nm.

[0115] The second optical auxiliary layer: the material is NPB, and the film thickness is 14.5 nm.

[0116] Second emitting layer (green emitting layer): The material is a mixture of GH and GD. GH is the host material, GD is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host material and the guest material is 8%, and the film thickness is 33nm.

[0117] The second hole blocking layer: the material is TPBi, and the film thickness is 5nm.

[0118] Second electron transport layer: The material is a mixture of BCP and Liq. The mass ratio of BCP to Liq is 1:1, and the film thickness is 30nm.

[0119] Electron injection layer: The material is Yb and the film thickness is 1nm.

[0120] Cathode: The material is a mixture of Mg and Ag, with a film thickness of 13nm.

[0121] Light extraction layer: The material is NPB, and the film thickness is 60nm.

[0122] Green light emitting device comparative example 1:

[0123] Compared to the reference example green light-emitting device, except for the first hole transport layer, the first optical auxiliary layer, the second hole transport layer, and the second optical auxiliary layer, the parameters of the other film layers of the green light-emitting device in Comparative Example 1 are the same as those of the corresponding film layers of the reference example green light-emitting device. For the sake of brevity, only the parameters of the first hole transport layer, the first optical auxiliary layer, the second hole transport layer, and the second optical auxiliary layer of the green light-emitting device in Comparative Example 1 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers of the reference example green light-emitting device.

[0124] The first hole transport layer: the material is m-MTDATA, and the film thickness is 99 nm.

[0125] The first optical auxiliary layer: the material is NPB, and the film thickness is 43nm.

[0126] The second hole transport layer: the material is m-MTDATA, and the film thickness is 34 nm.

[0127] The second optical auxiliary layer: the material is NPB, and the film thickness is 17nm.

[0128] Green light emitting device comparative example 2:

[0129] Compared to the green light-emitting device in comparative example 1, except for the hole injection layer, the parameters of the other film layers in the green light-emitting device in comparative example 2 are the same as those of the corresponding film layers in the green light-emitting device in comparative example 1. For the sake of brevity, only the parameters of the hole injection layer in the green light-emitting device in comparative example 2 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers in the green light-emitting device in comparative example 1.

[0130] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 10nm.

[0131] Reference example red light emitting device:

[0132] Anode: The material is ITO.

[0133] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 1%, and the film thickness is 10nm.

[0134] The first hole transport layer: the material is m-MTDATA, and the film thickness is 18 nm.

[0135] The first optical auxiliary layer: the material is NPB, and the film thickness is 32nm.

[0136] First luminescent layer (red luminescent layer): The material is a mixture of RH and RD. The chemical structures of RH and RD can be found in the previous description. RH is the host material, RD is the guest material, and the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 2%. The film thickness is 45 nm.

[0137] The first hole blocking layer: the material is TPBi, and the film thickness is 5 nm.

[0138] First electron transport layer: The material is a mixture of BCP and Liq. The mass ratio of BCP to Liq is 1:1, and the film thickness is 20nm.

[0139] N-type charge generation layer: the material is a mixture of BCP and Yb, BCP is the host material, Yb is the guest material, the ratio of the mass of the guest material to the sum of the masses of the host material and the guest material is 0.5%, and the film thickness is 18nm.

[0140] P-type charge generation layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 1%, and the film thickness is 9nm.

[0141] The second hole transport layer: the material is m-MTDATA, and the film thickness is 14.5 nm.

[0142] The second optical auxiliary layer: the material is NPB, and the film thickness is 32nm.

[0143] Second emitting layer (red emitting layer): Material is a mixture of RH and RD. RH is the host material, RD is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host material and the guest material is 2%, and the film thickness is 45nm.

[0144] The second hole blocking layer: the material is TPBi, and the film thickness is 5nm.

[0145] Second electron transport layer: The material is a mixture of BCP and Liq. The mass ratio of BCP to Liq is 1:1, and the film thickness is 30nm.

[0146] Electron injection layer: The material is Yb and the film thickness is 1nm.

[0147] Cathode: The material is a mixture of Mg and Ag, with a film thickness of 13nm.

[0148] Light extraction layer: The material is NPB, and the film thickness is 60nm.

[0149] Comparative Example 1 of Red Light Emitting Device:

[0150] Compared to the reference example red light-emitting device, except for the first hole transport layer, first optical auxiliary layer, p-type charge generation layer, second hole transport layer, and second optical auxiliary layer, the parameters of the other film layers of the red light-emitting device in Comparative Example 1 are the same as those of the corresponding film layers in the reference example red light-emitting device. For the sake of brevity, only the parameters of the first hole transport layer, first optical auxiliary layer, p-type charge generation layer, second hole transport layer, and second optical auxiliary layer of the red light-emitting device in Comparative Example 1 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers in the reference example red light-emitting device.

[0151] The first hole transport layer: the material is m-MTDATA, and the film thickness is 99 nm.

[0152] The first optical auxiliary layer: the material is NPB, and the film thickness is 86nm.

[0153] P-type charge generation layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 9nm.

[0154] The second hole transport layer: the material is m-MTDATA, and the film thickness is 34 nm.

[0155] The second optical auxiliary layer: the material is NPB, and the film thickness is 30nm.

[0156] Comparative Example 2 of Red Light Emitting Device:

[0157] Compared to the red light-emitting device in Comparative Example 1, except for the hole injection layer, the parameters of the other film layers in Comparative Example 2 are the same as those of the corresponding film layers in Comparative Example 1. For the sake of brevity, only the parameters of the hole injection layer in Comparative Example 2 are listed below. The parameters of the other film layers can refer to the parameters of the corresponding film layers in Comparative Example 1.

[0158] Hole injection layer: The material is a mixture of m-MTDATA and F4TCNQ. m-MTDATA is the host material, F4TCNQ is the guest material, the ratio of the mass of the guest material to the sum of the mass of the host and guest materials is 5%, and the film thickness is 10nm.

[0159] Table 1 lists the optoelectronic performance parameters of the reference example light-emitting device and the light-emitting device of Comparative Example 1. Assuming the voltage, luminous efficiency (EQE, or external quantum efficiency), room temperature lifetime (LT95@25°C), and high temperature lifetime (LT95@85°C) of the reference example light-emitting device as 100%, the voltage, luminous efficiency, room temperature lifetime, and high temperature lifetime of the light-emitting device of Comparative Example 1 were investigated relative to those of the reference example light-emitting device.

[0160] Table 1 Photoelectric performance parameters of the reference example light emitting device and the comparative example 1 light emitting device

[0161] As can be seen from Table 1, compared with the red light-emitting device reference example, the voltage of the red light-emitting device in comparative example 1 did not change, the luminous efficiency was increased to 102%, the normal temperature life was increased to 107%, and the high temperature life was increased to 110%; compared with the green light-emitting device reference example, the voltage of the green light-emitting device in comparative example 1 was increased to 101%, the luminous efficiency was increased to 103%, the normal temperature life was increased to 109%, and the high temperature life was increased to 113%; compared with the blue light-emitting device reference example, the voltage of the blue light-emitting device in comparative example 1 was increased to 101%, the luminous efficiency was increased to 102%, the normal temperature life was increased to 113%, and the high temperature life was increased to 115%.

[0162] As can be seen, compared to the corresponding reference example light-emitting devices, the luminous efficiency of the red, green, and blue light-emitting devices in Comparative Example 1, the light-emitting devices in Comparative Example 1, have all been improved to a certain extent, and their lifespans have been effectively improved, with a particularly significant increase in high-temperature lifespan. The significant improvements in luminous efficiency and lifespan of the light-emitting devices in Comparative Example 1 are due to the optimization of the thicknesses and thickness ratios of certain film layers in the light-emitting devices in Comparative Example 1, as compared to the reference example light-emitting devices, as can be seen in Table 2 below.

[0163] Table 2 lists several thickness parameters and thickness ratios between various film layers for the reference example light-emitting device and the light-emitting device of Comparative Example 1. As can be seen from Table 2, compared to the corresponding reference example light-emitting device, the first distance d1 (the distance between the first light-emitting layer and the anode), the second distance d2 (the distance between the first light-emitting layer and the second light-emitting layer), the fourth distance d4 (the distance between the second light-emitting layer and the anode), and the fifth distance d5 (the distance between the anode and the cathode) of the red, green, and blue light-emitting devices of Comparative Example 1 are all increased to a certain extent. This increases the distance between the first and second light-emitting layers and the anode, thereby reducing or even preventing the effects of anode roughness and residual impurities on the first and second light-emitting layers. This helps improve the stability of the light-emitting characteristics of the light-emitting device, thereby contributing to improved luminous efficiency and extended service life, particularly at high temperatures. In addition, it can be seen from Table 2 that the d1 / d5 values ​​of the red, green, and blue light-emitting devices of the reference example are all less than 36%, while the d1 / d5 values ​​of the red, green, and blue light-emitting devices of Comparative Example 1 are all between 36% and 50%; the d4 / d5 values ​​of the green and blue light-emitting devices of the reference example are all less than 70%, while the d4 / d5 values ​​of the red, green, and blue light-emitting devices of Comparative Example 1 are all between 70% and 85%; the d2 / d5 value of the red light-emitting device of the reference example does not fall between 20% and 30%, while the d2 / d5 value of the red light-emitting device of Comparative Example 1 falls between 20% and 30%; the d2 / d5 value of the green light-emitting device of the reference example does not fall between 25% and 35%, while the d2 / d5 value of the green light-emitting device of Comparative Example 1 falls between 25% and 35%; and the d2 / d5 value of the blue light-emitting device of Comparative Example 1 falls between 31% and 45%. As mentioned above, the value of d1 / d5 is set between 36% and 50%, the value of d4 / d5 is set between 70% and 85%, the value of d2 / d5 of the red light-emitting device is set between 20% and 30%, the value of d2 / d5 of the green light-emitting device is set between 25% and 35%, and the value of d2 / d5 of the blue light-emitting device is set between 31% and 45%. The setting of these ratios can ensure the microcavity effect of the light-emitting device and ensure that the light-emitting device has excellent light color and high efficiency gain, which helps to further improve the luminous efficiency of the light-emitting device and extend the service life of the light-emitting device, especially the high-temperature life.

[0164] Table 2 Thickness parameters of the reference example light emitting device and the comparative example 1 light emitting device

[0165] 2 , in some embodiments, the conductivity of the hole injection layer 1024 is less than the conductivity of the P-type charge generation layer 1042 , which helps to reduce lateral current crosstalk.

[0166] In some embodiments, both the hole injection layer 1024 and the p-type charge generation layer 1042 include a host material and a guest material. The guest material of the hole injection layer 1024 is the same as the guest material of the p-type charge generation layer 1042. Furthermore, a first ratio of the mass of the guest material in the hole injection layer 1024 to the sum of the masses of the host material and the guest material is less than a second ratio of the mass of the guest material in the p-type charge generation layer 1042 to the sum of the masses of the host material and the guest material. In other words, the guest content in the hole injection layer 1024 is less than the guest content in the p-type charge generation layer 1042. By making the guest content in the hole injection layer 1024 less than the guest content in the p-type charge generation layer 1042, the generation of color crosstalk is reduced.

[0167] The parameters of the light-emitting device comparative examples 1 and 2 can be used to further demonstrate the conclusion that "a guest content in the hole injection layer 1024 that is smaller than a guest content in the P-type charge generation layer 1042 is beneficial to reducing the generation of color crosstalk."

[0168] As described above, in the red light-emitting device comparative example 1, the green light-emitting device comparative example 1, and the blue light-emitting device comparative example 1, the hole injection layer includes a host material m-MTDATA and a guest material F4TCNQ, and a first ratio of the mass of F4TCNQ to the sum of the masses of m-MTDATA and F4TCNQ is 1%; and the p-type charge generation layer includes a host material m-MTDATA and a guest material F4TCNQ, and a second ratio of the mass of F4TCNQ to the sum of the masses of m-MTDATA and F4TCNQ is 5%. That is, in the red light-emitting device comparative example 1, the green light-emitting device comparative example 1, and the blue light-emitting device comparative example 1, the guest content in the hole injection layer is less than the guest content in the p-type charge generation layer.

[0169] As described above, in Comparative Example 2 of the red light-emitting device, Comparative Example 2 of the green light-emitting device, and Comparative Example 2 of the blue light-emitting device, the hole injection layer includes a host material m-MTDATA and a guest material F4TCNQ, and a first ratio of the mass of F4TCNQ to the sum of the masses of m-MTDATA and F4TCNQ is 5%; and the p-type charge generation layer includes a host material m-MTDATA and a guest material F4TCNQ, and a second ratio of the mass of F4TCNQ to the sum of the masses of m-MTDATA and F4TCNQ is 5%. That is, in Comparative Example 2 of the red light-emitting device, Comparative Example 2 of the green light-emitting device, and Comparative Example 2 of the blue light-emitting device, the guest content in the hole injection layer is equal to the guest content in the p-type charge generation layer.

[0170] Figure 3 shows spectra of a red, green, and blue light-emitting device in comparative example 1, where curves R, G, and B represent the spectra of the red, green, and blue light-emitting devices in comparative example 1, respectively. Figure 4 shows a spectra of a green light-emitting device in comparative example 2, Figure 5 shows a spectra of a red light-emitting device in comparative example 2, and Figure 6 shows a spectra of a blue light-emitting device in comparative example 2. In Figures 3 to 6, the abscissa represents wavelength, and the ordinate represents normalized intensity.

[0171] In the spectrum diagram of Figure 3, each of the R, G, and B curves has only one peak, indicating that there is no color crosstalk between the red light emitted by the red light-emitting device in Comparative Example 1, the green light emitted by the green light-emitting device in Comparative Example 1, and the blue light emitted by the blue light-emitting device in Comparative Example 1. In these light-emitting devices in Comparative Example 1, the guest content in the hole injection layer is less than the guest content in the p-type charge generation layer.

[0172] However, in the spectrum diagram of Figure 4, Curve G includes not only a main peak but also a second peak with a wavelength of approximately 620 nm. This indicates that the green light-emitting device in Comparative Example 2 emits not only green light but also a certain amount of red light, exhibiting color crosstalk. Similarly, in the spectrum diagram of Figure 5, Curve R includes not only a main peak but also a second peak with a wavelength of approximately 540 nm. This indicates that the red light-emitting device in Comparative Example 2 emits not only red light but also a certain amount of green light, exhibiting color crosstalk. In both the red and green light-emitting devices in Comparative Example 2, the guest content in the hole injection layer is equal to the guest content in the p-type charge generation layer.

[0173] 3 to 5 , it can be seen that when the guest content in the hole injection layer is less than the guest content in the P-type charge generation layer, it is beneficial to avoid the generation of color crosstalk.

[0174] It should be noted that the specific features, structures, materials, or characteristics described above with respect to the light-emitting device 100 may be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described above with respect to the light-emitting device 100 and the features of the different embodiments or examples may be combined with each other without exceeding the scope of protection of the present disclosure, unless they are mutually inconsistent.

[0175] FIG7 shows a schematic structural diagram of a light-emitting device 200. Similar to the light-emitting device 100, the light-emitting device 200 also includes an anode 101, a first light-emitting unit 102, a second light-emitting unit 103, a first hole transport layer 1022, a first electron transport layer 1023, a hole injection layer 1024, a first hole blocking layer 1025, a second hole transport layer 1032, a second electron transport layer 1033, an electron injection layer 1034, a second hole blocking layer 1035, an N-type charge generation layer 1041, a P-type charge generation layer 1042, and a cathode 105. In some embodiments, the thickness T1 of the hole injection layer 1024 is less than or equal to the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, i.e., T1 ≤ T2 + T3. In some alternative embodiments, the thickness T1 of the hole injection layer 1024 can be greater than the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, i.e., T1>T2+T3. The sum of the thickness T5 of the N-type charge generation layer, the thickness T6 of the P-type charge generation layer 1042, and the thickness T7 of the second hole transport layer 1032 is less than the thickness T4 of the first hole transport layer 1022, i.e., T4>T5+T6+T7. The structures and functions of these layers, as well as the beneficial technical effects brought about by the thickness relationship between the layers, are the same as those described above regarding the light-emitting device 100 and will not be repeated here for the sake of brevity.

[0176] Unlike the light-emitting device 100, the light-emitting device 200 includes multiple light-emitting layers that emit light of different colors. Specifically, in the light-emitting device 200, the first light-emitting unit 102 includes a first light-emitting layer 1021R, a third light-emitting layer 1021G, and a fifth light-emitting layer 1021B. The first light-emitting layer 1021R, the third light-emitting layer 1021G, and the fifth light-emitting layer 1021B are separated from each other and emit light of different colors. The second light-emitting unit 103 includes a second light-emitting layer 1031R, a fourth light-emitting layer 1031G, and a sixth light-emitting layer 1031B. The second light-emitting layer 1031R, the fourth light-emitting layer 1031G, and the sixth light-emitting layer 1031B are separated from each other and emit light of different colors. The first light-emitting layer 1021R and the second light-emitting layer 1031R both emit light of a first color, which may be, for example, red light; the third light-emitting layer 1021G and the fourth light-emitting layer 1031G both emit light of a second color, which may be, for example, green light; and the fifth light-emitting layer 1021B and the sixth light-emitting layer 1031B both emit light of a third color, which may be, for example, blue light. In this way, the light-emitting device 200 can achieve color display.

[0177] It can be understood that the light-emitting device 200 includes multiple sub-light-emitting devices, which may include a first sub-light-emitting device, a second sub-light-emitting device, and a third sub-light-emitting device. For example, the first sub-light-emitting device may be a red sub-light-emitting device, the second sub-light-emitting device may be a green sub-light-emitting device, and the third sub-light-emitting device may be a blue sub-light-emitting device. The first sub-light-emitting device includes a first light-emitting layer 1021R and a second light-emitting layer 1031R, the second sub-light-emitting device includes a third light-emitting layer 1021G and a fourth light-emitting layer 1031G, and the third sub-light-emitting device includes a fifth light-emitting layer 1021B and a sixth light-emitting layer 1031B. The orthographic projections of the first light-emitting layer 1021R and the second light-emitting layer 1031R on the anode 101 at least partially overlap, the orthographic projections of the third light-emitting layer 1021G and the fourth light-emitting layer 1031G on the anode 101 at least partially overlap, and the orthographic projections of the fifth light-emitting layer 1021B and the sixth light-emitting layer 1031B on the anode 101 at least partially overlap.

[0178] The first light-emitting layer 1021R and the second light-emitting layer 1031R can have the same thickness or different thicknesses; the third light-emitting layer 1021G and the fourth light-emitting layer 1031G can have the same thickness or different thicknesses; the fifth light-emitting layer 1021B and the sixth light-emitting layer 1031B can have the same thickness or different thicknesses. The thicknesses of the first light-emitting layer 1021R, the third light-emitting layer 1021G, and the fifth light-emitting layer 1021B can be different, partially the same, or completely the same. The thicknesses of the second light-emitting layer 1031R, the fourth light-emitting layer 1031G, and the sixth light-emitting layer 1031B can be different, partially the same, or completely the same.

[0179] For example, the first hole transport layer 1022, the first electron transport layer 1023, the hole injection layer 1024, the first hole blocking layer 1025, the second hole transport layer 1032, the second electron transport layer 1033, the electron injection layer 1034, the second hole blocking layer 1035, the charge generation layer 104, and the cathode 105 and other film layers can be shared by multiple sub-light-emitting devices of the light-emitting device 200.

[0180] A first distance d1R between the anode 101 and the first light-emitting layer 1021R is greater than or equal to a second distance d2R between the first light-emitting layer 1021R and the second light-emitting layer 1031R, i.e., d1R ≥ d2R. A first distance d1G between the anode 101 and the third light-emitting layer 1021G is greater than or equal to a second distance d2G between the third light-emitting layer 1021G and the fourth light-emitting layer 1031G, i.e., d1G ≥ d2G. A first distance d1B between the anode 101 and the fifth light-emitting layer 1021B is greater than or equal to a second distance d2B between the fifth light-emitting layer 1021B and the sixth light-emitting layer 1031B, i.e., d1B ≥ d2B.

[0181] By making d1R≥d2R, d1G≥d2G, and d1B≥d2B, on the one hand, the total thickness of each film layer included in the second distance range is reduced, which helps to reduce the difficulty of charge injection within the second distance range and improves the charge transmission capability in the second light-emitting unit 103, thereby helping to balance the charge injection and transmission in the first light-emitting unit 102 and the second light-emitting unit 103, improving the problem of device performance degradation (especially device life) due to charge imbalance, and maximizing the advantages of the stacked light-emitting device in improving life. On the other hand, d1R ≥ d2R, d1G ≥ d2G, ​​and d1B ≥ d2B mean that the distances between the anode 101 and the first light-emitting layer 1021R, the third light-emitting layer 1021G, and the fifth light-emitting layer 1021B are all relatively large. Therefore, the first light-emitting layer 1021R, the second light-emitting layer 1031R above the first light-emitting layer 1021R, the third light-emitting layer 1021G, the fourth light-emitting layer 1031G above the third light-emitting layer 1021G, the fifth light-emitting layer 1021B, and the sixth light-emitting layer 1031B above the fifth light-emitting layer 1021B can all be kept away from the anode 101. This can reduce or even eliminate the effects of the roughness of the anode 101 and residual impurities on the luminescent characteristics of each light-emitting layer, thereby improving the stability of the luminescent characteristics of the light-emitting device 200, thereby helping to improve the luminous efficiency of the light-emitting device 200 and extend the service life of the light-emitting device 200, especially its high-temperature service life.

[0182] The distance between the second light-emitting layer 1031R and the cathode 105 is a third distance d3R, the distance between the fourth light-emitting layer 1031G and the cathode 105 is a third distance d3G, and the distance between the sixth light-emitting layer 1031B and the cathode 105 is a third distance d3B. In some embodiments, the first distance, the second distance, and the third distance satisfy d1R ≥ d3R ≥ d2R, d1G ≥ d3G ≥ d2G, ​​and d1B ≥ d3B ≥ d2B. This means that the distances from the first and second light-emitting layers 1021R and 1031R to the anode 101, the distances from the third and fourth light-emitting layers 1021G and 1031G to the anode 101, and the distances from the fifth and sixth light-emitting layers 1021B and 1031B to the anode 101 are further increased. This helps further reduce or even prevent the effects of anode roughness and residual impurities on the luminescent properties of each light-emitting layer, thereby further improving the luminous efficiency of the light-emitting device 200 and extending its service life, particularly at high temperatures.

[0183] 7 , to coordinate with the light-emitting layers emitting light of different colors, the light-emitting device 200 further provides multiple optical auxiliary layers. Specifically, the first light-emitting unit 102 further includes a first optical auxiliary layer 1026R located between the first hole transport layer 1022 and the first light-emitting layer 1021R, a third optical auxiliary layer 1026G located between the first hole transport layer 1022 and the third light-emitting layer 1021G, and a fifth optical auxiliary layer 1026B located between the first hole transport layer 1022 and the fifth light-emitting layer 1021B. The second light-emitting unit 103 further includes a second optical auxiliary layer 1036R located between the second hole transport layer 1032 and the second light-emitting layer 1031R, a fourth optical auxiliary layer 1036G located between the second hole transport layer 1032 and the fourth light-emitting layer 1031G, and a sixth optical auxiliary layer 1036B located between the second hole transport layer 1032 and the sixth light-emitting layer 1031B. On the one hand, the optical auxiliary layer can reduce the hole injection barrier, and on the other hand, it can adjust the length of the optical microcavity so that the optical microcavity length is more matched with the emission wavelength.

[0184] The thickness T9R of the first optical auxiliary layer 1026R is greater than or equal to the thickness T8R of the second optical auxiliary layer 1036R, that is, T9R ≥ T8R. The thickness T9G of the third optical auxiliary layer 1026G is greater than or equal to the thickness T8G of the fourth optical auxiliary layer 1036G, that is, T9G ≥ T8G. The thickness T9B of the fifth optical auxiliary layer 1026B is greater than or equal to the thickness T8B of the sixth optical auxiliary layer 1036B, that is, T9B ≥ T8B. In the light-emitting device 200, by ensuring that T9R ≥ T8R, T9G ≥ T8G, and T9B ≥ T8B, the hole injection rate in the first light-emitting unit 102 is slowed down compared to the hole injection rate in the second light-emitting unit 103, thereby helping to promote charge balance between the first light-emitting unit 102 and the second light-emitting unit 103. On the other hand, slowing down the hole injection rate in the first light-emitting unit 102 helps further improve the injection ratio of electrons and holes in each light-emitting layer of the first light-emitting unit 102, thereby helping to further promote the injection balance of electrons and holes in the first light-emitting unit 102. Charge balance within a device is a key factor in achieving high efficiency and long life. Therefore, this design is conducive to improving the luminous efficiency of the light-emitting device 200 and extending the service life of the light-emitting device 200.

[0185] As shown in FIG7 , the distance between the anode 101 and the cathode 105 is the fifth distance d5. In the light-emitting device 200, the ratio of the second distance d2R to the fifth distance d5 can be 20% to 30%, the ratio of the second distance d2G to the fifth distance d5 can be 25% to 35%, and the ratio of the second distance d2B to the fifth distance d5 can be 31% to 45%. It can be seen that for sub-light-emitting devices of different colors, the ratio range of the second distance to the fifth distance is slightly different. Through such a design, the microcavity effect of the light-emitting device 200 can be ensured, and the light-emitting device 200 can be ensured to have excellent light output color and high efficiency gain, thereby helping to further improve the luminous efficiency of the light-emitting device 200 and extend the service life of the light-emitting device 200, especially the high-temperature service life.

[0186] The distance between the second light-emitting layer 1031R and the anode 101 is a fourth distance d4R, the distance between the fourth light-emitting layer 1031G and the anode 101 is a fourth distance d4G, and the distance between the sixth light-emitting layer 1031B and the anode 101 is a fourth distance d4B. In some embodiments, the ratio of the fourth distance d4R to the fifth distance d5 may be 70% to 85%, the ratio of the fourth distance d4G to the fifth distance d5 may be 70% to 85%, and the ratio of the fourth distance d4B to the fifth distance d5 may be 70% to 85%. In some embodiments, the ratio of the first distance d1R to the fifth distance d5 may be 36% to 50%, the ratio of the first distance d1G to the fifth distance d5 may be 36% to 50%, and the ratio of the first distance d1B to the fifth distance d5 may be 36% to 50%.

[0187] 8 shows a light emitting device 300, which serves as a reference example of the light emitting device 200. The light emitting device 300 has the same structure as the light emitting device 200 except that the thickness of some film layers is different.

[0188] Table 3 lists the thickness of each film layer of the light-emitting device 200 according to the embodiment of the present disclosure (corresponding to the “thickness of the film layer of the embodiment of the present disclosure (nm)” in Table 3) and the thickness of each film layer of the reference example light-emitting device 300 (corresponding to the “thickness of the film layer of the reference example (nm)” in Table 3).

[0189] Table 3 Film thickness of light emitting device 200 and light emitting device 300

[0190] Table 4 lists the thickness relationship of certain film layers of the light emitting device 200 provided according to the embodiment of the present disclosure and the light emitting device 300 of the reference example.

[0191] Table 4 Relationship between the thickness of certain film layers of the light emitting device 200 and the light emitting device 300

[0192] It can be seen from the data provided in Tables 3 and 4 that in the light-emitting device 200, the thickness T1 of the hole injection layer 1024 is greater than the sum of the thickness T2 of the first hole blocking layer 1025 and the thickness T3 of the first electron transport layer 1023, that is, T1>T2+T3 is satisfied; while in the reference example light-emitting device 300, the thickness T1' of the hole injection layer 1024 is less than the sum of the thickness T2' of the first hole blocking layer 1025 and the thickness T3' of the first electron transport layer 1023, that is, T1'>T2'+T3' is not satisfied. In the light-emitting device 200, the thickness T4 of the first hole transport layer 1022 is greater than the sum of the thickness T5 of the N-type charge generation layer 1041, the thickness T6 of the P-type charge generation layer 1042, and the thickness T7 of the second hole transport layer 1032, that is, T4>T5+T6+T7; while in the reference example light-emitting device 300, the thickness T4' of the first hole transport layer 1022 is less than the sum of the thickness T5' of the N-type charge generation layer 1041, the thickness T6' of the P-type charge generation layer 1042, and the thickness T7' of the second hole transport layer 1032, that is, T4'>T5'+T6'+T7' is not satisfied. In the light-emitting device 200, the thickness of the lower optical auxiliary layer is greater than that of the upper optical auxiliary layer. Here, the thickness of the lower optical auxiliary layer refers to the thickness T9R of the first optical auxiliary layer 1026R, the thickness T9G of the third optical auxiliary layer 1026G, and the thickness T9B of the fifth optical auxiliary layer 1026B. The thickness of the upper optical auxiliary layer refers to the thickness T8R of the second optical auxiliary layer 1036R, the thickness T8G of the fourth optical auxiliary layer 1036G, and the thickness T8B of the sixth optical auxiliary layer 1036B. In the light-emitting device 200, T9R>T8R, T9G>T8G, and T9B>T8B are satisfied. In the reference example light-emitting device 300, , the thickness of the lower optical auxiliary layer is less than or equal to the thickness of the upper optical auxiliary layer. Similarly, here, the thickness of the lower optical auxiliary layer refers to the thickness T9R' of the first optical auxiliary layer 1026R, the thickness T9G' of the third optical auxiliary layer 1026G, and the thickness T9B' of the fifth optical auxiliary layer 1026B. The thickness of the upper optical auxiliary layer refers to the thickness T8R' of the second optical auxiliary layer 1036R, the thickness T8G' of the fourth optical auxiliary layer 1036G, and the thickness T8B' of the sixth optical auxiliary layer 1036B. In the reference example light-emitting device 300, T9R'>T8R', T9G'>T8G', and T9B'>T8B' are not satisfied.

[0193] Table 5 lists the relationship between the first distance d1 and the second distance d2 of the light emitting device 200 according to the embodiment of the present disclosure and the light emitting device 300 of the reference example, wherein the values ​​of the first distance d1 and the second distance d2 can be obtained according to the data listed in Table 3.

[0194] Table 5 Relationship between d1 and d2 of light emitting device 200 and light emitting device 300

[0195] As can be seen from Table 5, in light-emitting device 200, the first distance d1 within the red sub-device (i.e., the sub-device containing the first light-emitting layer 1021R and the second light-emitting layer 1031R) is 99 nm, and the second distance d2 within the red sub-device is 90 nm, with d1 > d2. In contrast, in reference example light-emitting device 300, the first distance d1 within the red sub-device is 51 nm, and the second distance d2 within the red sub-device is 108 nm, with d1 < d2. In light-emitting device 200, the first distance d1 within the green sub-device (i.e., the sub-device containing the third light-emitting layer 1021G and the fourth light-emitting layer 1031G) is 71 nm, and the second distance d2 within the green sub-device is 62 nm, with d1 > d2. In reference example light-emitting device 300, the first distance d1 within the green sub-device is 37 nm, and the second distance d2 within the green sub-device is 90 nm, with d1 < d2. In the light-emitting device 200, the first distance d1 within the blue sub-light-emitting device (i.e., the sub-light-emitting device where the fifth light-emitting layer 1021B and the sixth light-emitting layer 1031B are located) is equal to 57 nm, and the second distance d2 within the blue sub-light-emitting device is equal to 47 nm, and d1>d2; while in the reference example light-emitting device 300, the first distance d1 within the blue sub-light-emitting device is equal to 30 nm, and the second distance d2 within the blue sub-light-emitting device is equal to 73 nm, and d1<d2.

[0196] It can be seen that, compared with the reference example light emitting device 300 , by adjusting the thickness of certain film layers of the light emitting device 200 , each sub-light emitting device of the light emitting device 200 satisfies d1>d2.

[0197] Table 6 lists the lifespan of the light-emitting device 200 provided according to the embodiment of the present disclosure and the lifespan of the reference light-emitting device 300. The voltage and lifespan of the reference light-emitting device 300 were both set to 100%. Under the same conditions as the light-emitting device 300, the lifespan of the light-emitting device 200 was tested, resulting in a voltage of 100% and a lifespan of 110%. This shows that the lifespan of the light-emitting device 200 is improved compared to the light-emitting device 300. The light-emitting device 200 can more effectively meet the application requirements of stacked light-emitting devices in medium- and large-sized, automotive, and other display applications, broadening the application scenarios of light-emitting devices.

[0198] Table 6 Lifespan of the light emitting device 200 and the light emitting device 300

[0199] Combined with the data in Tables 3 to 6 and the description above, the reasons for the improved life of the light-emitting device 200 can be roughly summarized as follows: (1) By making d1 ≥ d2, on the one hand, the difficulty of injecting charges between the various film layers covered within the second distance d2 can be reduced, and the charge transmission capability in the second light-emitting unit 103 can be improved, thereby balancing the charge injection and transmission in the first light-emitting unit 102 and the second light-emitting unit 103, improving the problem of reduced device life due to charge imbalance, and maximizing the advantages of the stacked light-emitting device in improving life; (2) By making d1 ≥ d2, on the other hand, the first light-emitting layer and the second light-emitting layer can be kept away from the anode 101, so that the influence of the roughness of the anode 101 and the residual impurities on the light-emitting characteristics of the first light-emitting layer and the second light-emitting layer can be reduced or even avoided, which helps to improve the stability of the light-emitting characteristics of the light-emitting device, thereby helping to improve the light-emitting efficiency of the light-emitting device and extend the service life of the light-emitting device; (3) By making T4 > T5 + T6 + T7, compared with the hole injection speed of the second light-emitting unit 103, can slow down the hole injection speed of the first light-emitting unit 102, thereby effectively promoting the charge balance between the first light-emitting unit 102 and the second light-emitting unit 103. In addition, such a design can also slow down the hole injection speed inside the second light-emitting unit 103 and speed up the electron injection speed, which helps to promote the injection balance of electrons and holes inside the second light-emitting unit 103, thereby helping to extend the service life of the light-emitting device 200; (4) By making T9 ≥ T8, compared with the second light-emitting unit 103, the hole injection speed of the first light-emitting unit 102 can be slowed down, thereby helping to promote the charge balance between the first light-emitting unit 102 and the second light-emitting unit 103. On the other hand, slowing down the hole injection speed of the first light-emitting unit 102 helps to further improve the injection ratio of electrons and holes in the first light-emitting layer 1021, thereby helping to further promote the injection balance of electrons and holes in the first light-emitting unit 102, thereby helping to extend the service life of the light-emitting device 200.

[0200] For other technical effects of the light-emitting device 200 , reference may be made to the technical effects of the light-emitting device 100 described in the previous embodiments, and for the sake of brevity, they will not be described again here.

[0201] Another embodiment of the present disclosure provides a light-emitting device, which can be described with reference to FIG2 . The light-emitting device includes: an anode 101; a first light-emitting unit 102, located on the anode 101 and including a first light-emitting layer 1021; a second light-emitting unit 103, located on a side of the first light-emitting unit 102 away from the anode 101 and including a second light-emitting layer 1031; and a cathode 105, located on a side of the second light-emitting unit 103 away from the anode 101. The first light-emitting layer 1021 and the second light-emitting layer 1031 emit light of the same color. The distance between the anode 101 and the first light-emitting layer 1021 is a first distance d1, the distance between the first light-emitting layer 1021 and the second light-emitting layer 1031 is a second distance d2, and the distance between the second light-emitting layer 1031 and the cathode 105 is a third distance d3, where d1, d2, and d3 satisfy d1 ≥ d3 ≥ d2.

[0202] The roughness of the anode 101 and the degree of impurity removal during the preparation process will affect the stability of the light-emitting device formed by the evaporation process. The higher the roughness of the anode 101, or the more impurities remain, the more likely it is to cause the light-emitting device to have adverse phenomena such as leakage or breakdown. By making d1≥d3≥d2, it means that there is a long distance between the first light-emitting layer 1021 and the anode 101, and between the second light-emitting layer 1031 and the anode 101. In this way, the influence of the roughness of the anode 101 and the residual impurities on the luminescent characteristics of the first light-emitting layer 1021 and the second light-emitting layer 1031 can be reduced or even avoided, thereby improving the stability of the luminescent characteristics of the light-emitting device. In addition, in the case where the light-emitting device is a top-emitting device, this structural design can also ensure the light color and efficiency of the top-emitting device, thereby helping to improve the luminous efficiency of the light-emitting device and extend the service life of the light-emitting device, especially the high-temperature life.

[0203] Figure 9 shows a schematic diagram of the structure of a display panel 400 according to an embodiment of the present disclosure. As shown in Figure 9, display panel 400 includes a substrate 108 and a plurality of light-emitting devices arranged on substrate 108. The light-emitting devices may be the light-emitting devices 100 or 200 described in any of the previous embodiments. The plurality of light-emitting devices are arranged in an array within display panel 400. In response to a drive signal, the light-emitting devices emit light of corresponding colors, enabling display panel 400 to achieve its display function.

[0204] As shown in FIG9 , the display panel 400 further includes a plurality of spacer pillars 106, which are located on one side of the substrate 108 where the plurality of light-emitting devices are arranged. As previously described, the light-emitting device includes a charge generation layer 104 located between the first light-emitting unit 102 and the second light-emitting unit 103. The charge generation layer 104 can be shared by the plurality of light-emitting devices of the display panel 400.

[0205] In an embodiment of the present disclosure, at least a portion of the charge generation layer 104 located between the plurality of light emitting devices is partitioned by a plurality of isolation pillars 106 .

[0206] Specifically, when the display panel 400 includes multiple light-emitting devices 100, each sub-pixel may be provided with a light-emitting device 100. The charge generation layer 104 is shared by the multiple light-emitting devices 100, and the multiple isolation columns 106 isolate at least the portion of the charge generation layer 104 located between the multiple light-emitting devices 100 to prevent lateral current from being generated between adjacent sub-pixels.

[0207] When the display panel 400 includes multiple light-emitting devices 200, the first sub-light-emitting device of the light-emitting device 200 can be located in a red sub-pixel of the display panel 400, the second sub-light-emitting device of the light-emitting device 200 can be located in a green sub-pixel of the display panel 400, and the third sub-light-emitting device of the light-emitting device 200 can be located in a blue sub-pixel of the display panel 400. The charge generation layer 104 is shared not only by the multiple light-emitting devices 200, but also by the multiple sub-light-emitting devices of each light-emitting device 200. In this case, as shown in FIG. 10 , the multiple spacers 106 not only isolate the portions of the charge generation layer 104 located between the multiple light-emitting devices 200, but also isolate the portions of the charge generation layer 104 located between the first, second, and third sub-light-emitting devices, thereby preventing the generation of lateral currents between adjacent sub-pixels.

[0208] It should be noted that the statement "a plurality of isolation columns 106 at least isolate the portion of the charge generation layer 104 located between the plurality of light-emitting devices" means that a plurality of isolation columns 106 will at least isolate certain portions of the charge generation layer 104. However, the embodiments of the present disclosure do not limit whether the isolation columns 106 will also isolate other film layers other than the charge generation layer 104. For example, in some embodiments, a plurality of isolation columns 106 not only isolate the portion of the charge generation layer 104 located between the plurality of light-emitting devices, but also isolate the portion of other film layers (such as the second hole transport layer 1032, etc.) located between the plurality of light-emitting devices. However, the cathode 105 is a continuous film layer and will not be isolated by the isolation columns 106. The type and quantity of film layers isolated by the isolation columns 106 can be flexibly designed according to specific requirements.

[0209] Isolation columns 106 can be used to prevent lateral currents from flowing between adjacent sub-pixels. Furthermore, by optimizing the thickness ratio of certain film layers (e.g., satisfying d1 ≥ d2 or d1 ≥ d3 ≥ d2) and increasing the overall thickness of the light-emitting device, the support strength of the film layer between the anode 101 and the cathode 105 can be enhanced, thereby reducing or even eliminating the probability of cathode 105 breaking in the region corresponding to isolation columns 106, thereby helping to reduce the power consumption of the light-emitting device.

[0210] 9 , the display panel 400 may further include an opposing substrate 109 and a sealant 110 disposed between the substrate 108 and the opposing substrate 109. The substrate 108 and the opposing substrate 109 may be layers made of, for example, an organic polymer. Examples of organic polymers for forming the substrate 108 and the opposing substrate 109 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyethersulfone, and the like.

[0211] Figure 11 shows a partial structural diagram of the display panel 400. As shown in Figure 11, the distance between the anode 101 and the cathode 105 is a fifth distance d5, and the thickness of the spacer 106 is T10. In some embodiments, the ratio of d5 to T10 is between 15% and 40%. For example, the ratio of d5 to T10 can be 15%, 20%, 27.5%, 30%, 40%, etc. By optimizing the thickness T10 of the spacer 106, the spacer 106 can better prevent the generation of lateral current between adjacent sub-pixels.

[0212] The display panel 400 may further include a pixel-defining layer 107. The pixel-defining layer 107 is used to define the regions of each sub-pixel. The pixel-defining layer 107 may be formed from a polymer resin. For example, the pixel-defining layer 107 may include a polyacrylate resin or a polyimide resin. Alternatively, the pixel-defining layer 107 may be formed from an inorganic material. The substrate 108 may be a glass substrate, a metal substrate, a plastic substrate, or the like.

[0213] It should be noted that Figure 11 is merely a schematic illustration of the relationship between the fifth distance d5 and the thickness T10 of the spacer 106. The film structure and positional relationship shown therein do not represent the film structure and positional relationship of an actual product. As previously mentioned, the cathode 105 is a continuous film layer, and the spacer 106 does not isolate the cathode 105.

[0214] Table 7 lists a comparison of power consumption of a reference example light-emitting device and a comparative example light-emitting device. The reference example light-emitting device may be the same as the reference example red light-emitting device, the reference example green light-emitting device, or the reference example blue light-emitting device described above, and the comparative example light-emitting device may be the same as the red light-emitting device in comparative example 1, the green light-emitting device in comparative example 1, or the blue light-emitting device in comparative example 1 described above. The reference example light-emitting device and the comparative example light-emitting device were tested with and without isolation pillars, respectively, to obtain the following four sets of data in Table 7.

[0215] Table 7 Comparison of power consumption of reference example light emitting device and comparative example light emitting device

[0216] As can be seen from Table 7, for the reference example light-emitting device, without the isolation pillars, the white light power consumption is 100%; after the isolation pillars are installed, the white light power consumption rises to 105%. In contrast, for the comparative example light-emitting device, the white light power consumption is 101% before and after the isolation pillars are installed, with no change in power consumption. This is because, after the isolation pillars are installed in the reference example light-emitting device, the film layer between the anode and cathode has poor support due to the relatively small overall thickness of the light-emitting device, resulting in the cathode easily breaking in the area corresponding to the isolation pillars. A broken cathode will increase the power consumption of the light-emitting device. In contrast, in the comparative example light-emitting device, by optimizing the thickness ratio of the light-emitting device's several film layers (for example, satisfying d1 ≥ d2 or d1 ≥ d3 ≥ d2) and increasing the overall thickness of the light-emitting device, the support of the film layer between the anode and cathode can be improved. As a result, even with the addition of isolation pillars, the probability of cathode breaking in the area corresponding to the isolation pillars can be reduced or even avoided, thereby substantially preventing an increase in the power consumption of the light-emitting device.

[0217] The display panel 400 may be any suitable type of display panel, including but not limited to an active-matrix organic light-emitting diode (AMOLED) display panel.

[0218] The display panel 400 may also include scan lines, data lines, power lines, and a plurality of sub-pixels. Each sub-pixel may include a switching transistor, a driving transistor, and a capacitor as a pixel driving circuit for driving an organic electroluminescent element. A first power supply voltage may be supplied to the driving transistor, and a second power supply voltage may be supplied to the organic electroluminescent element. The switching transistor outputs a data signal applied to the data line in response to a scan signal applied to the scan line. The capacitor is charged with a voltage corresponding to the data signal received from the switching transistor. The driving transistor is connected to the organic electroluminescent element. The driving transistor controls the driving current flowing through the organic electroluminescent element according to the amount of charge stored in the capacitor, thereby controlling the organic electroluminescent element to emit light.

[0219] The technical effects of the display panel 400 can refer to the technical effects of the light-emitting devices described in the previous embodiments. For the sake of brevity, the technical effects of the display panel 400 will not be repeatedly described here.

[0220] 12 shows a block diagram of an electronic device 500, which may include the display panel 400. The electronic device 500 may be any suitable type of electronic device with a display function, including but not limited to a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigation device, a near-eye display device such as VR or AR, etc.

[0221] In some embodiments, the electronic device 500 may be an organic electroluminescent display device, which includes the display panel 400, a timing controller, a gate driver, a data driver, a power supply, and other structures described in the previous embodiments.

[0222] The display panel 400 includes a plurality of gate lines GL and a plurality of data lines DL that intersect each other. The display panel 400 includes a plurality of sub-pixels PX arranged in an array, each of which includes a light-emitting device or sub-light-emitting device as described above. Each sub-pixel PX can be electrically connected to a corresponding gate line GL and a corresponding data line DL.

[0223] The timing controller controls the operation of the gate driver and the data driver. The timing controller receives input image data RGBD and an input control signal CONT from an external device (e.g., a host). The timing controller generates output image data RGBD', a first control signal CONT1, and a second control signal CONT2 based on the input image data RGBD and the input control signal CONT. The timing controller can generate the first control signal CONT1 based on the input control signal CONT. The first control signal CONT1 can be provided to the gate driver, and the driving timing of the gate driver can be controlled based on the first control signal CONT1. The timing controller can generate the second control signal CONT2 based on the input control signal CONT. The second control signal CONT2 can be provided to the data driver, and the driving timing of the data driver can be controlled based on the second control signal CONT2.

[0224] The gate driver receives a first control signal CONT1 from the timing controller. The gate driver generates a plurality of gate signals for driving the gate lines GL based on the first control signal CONT1. The gate driver may sequentially apply the plurality of gate signals to the gate lines GL.

[0225] The data driver receives the second control signal CONT2 and the output image data RGBD' from the timing controller. The data driver generates a plurality of data voltages based on the second control signal CONT2 and the output image data RGBD'. The data driver may apply the plurality of data voltages to the data lines DL.

[0226] The power supply supplies power to the sub-pixels PX in the display panel 400. In some embodiments, the power supply may also supply power to a timing controller, a gate driver, and a data driver.

[0227] The technical effects of the electronic device 500 can refer to the technical effects of the light-emitting devices described in the previous embodiments. For the sake of brevity, the technical effects of the electronic device will not be repeatedly described here.

[0228] It will be understood that although the terms first, second, third, etc. may be used to describe various elements, components, areas, layers and / or parts in this article, these elements, components, areas, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer or part from another element, component, area, layer or part. Therefore, the first element, component, area, layer or part discussed above can be referred to as the second element, component, area, layer or part without departing from the teachings of the present disclosure.

[0229] Spatially relative terms such as "row," "column," "under," "above," "left," "right," and the like may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures for ease of description. It will be understood that these spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figure is flipped, the element described as "under other elements or features" will be oriented as "above other elements or features." Thus, the exemplary term "under" can encompass both orientations of above and below. The device can be oriented otherwise (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly. In addition, it will also be understood that when a layer is referred to as "between two layers," it can be the only layer between the two layers, or one or more intermediate layers may also be present.

[0230] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "one", "an" and "the" are intended to also include the plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "include" and / or "comprise" when used in this specification specify the presence of the features, wholes, steps, operations, elements and / or parts, but do not exclude the presence of one or more other features, wholes, steps, operations, elements, parts and / or their groups or add one or more other features, wholes, steps, operations, elements, parts and / or their groups. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In the description of this specification, the description of the reference terms "one embodiment", "another embodiment" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily need to be directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. Furthermore, those skilled in the art may combine different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0231] It will be understood that when an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent to” another element or layer, it can be directly on, directly connected to, directly coupled to, or directly adjacent to another element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly adjacent to” another element or layer, no intervening elements or layers are present. However, in no case should “on” or “directly on” be interpreted as requiring that one layer completely cover the underlying layer.

[0232] Embodiments of the present disclosure are described herein with reference to schematic illustrations (and intermediate structures) of idealized embodiments of the present disclosure. Because of this, variations in the illustrated shapes, for example as a result of manufacturing techniques and / or tolerances, should be expected. Therefore, embodiments of the present disclosure should not be interpreted as being limited to the specific shapes of the regions illustrated herein, but should include shape deviations, for example, due to manufacturing. Therefore, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the actual shape of the regions of the device and are not intended to limit the scope of the present disclosure.

[0233] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant art and / or the context of this specification, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0234] As will be appreciated by those skilled in the art, although the various steps of the method of the present disclosure are described in a particular order in the accompanying drawings, this does not require or imply that the steps must be performed in that particular order unless the context clearly indicates otherwise. Additionally or alternatively, multiple steps may be combined into a single step and / or a single step may be broken down into multiple steps and performed. In addition, other method steps may be inserted between steps. An inserted step may represent an improvement to a method such as that described herein, or may be unrelated to the method. In addition, a given step may not be fully completed before the next step begins.

[0235] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0236] “At least one of A, B and C” has the same meaning as “at least one of A, B or C” and both include the following combinations of A, B and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B and C.

[0237] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0238] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A light-emitting device, comprising: anode; a first light-emitting unit, located on the anode and comprising a first light-emitting layer; as well as a second light-emitting unit, located on a side of the first light-emitting unit away from the anode and comprising a second light-emitting layer; The first light-emitting layer and the second light-emitting layer emit light of the same color, the distance between the anode and the first light-emitting layer is a first distance, the distance between the first light-emitting layer and the second light-emitting layer is a second distance, and the first distance is greater than or equal to the second distance.

2. The light emitting device according to claim 1, further comprising a charge generation layer located between the first light emitting unit and the second light emitting unit, in, The charge generation layer includes an N-type charge generation layer and a P-type charge generation layer, and the N-type charge generation layer is closer to the first light emitting unit than the P-type charge generation layer.

3. The light emitting device according to claim 2, wherein The first light-emitting unit also includes a first hole transport layer located between the anode and the first light-emitting layer, and the second light-emitting unit also includes a second hole transport layer located between the P-type charge generation layer and the second light-emitting layer, and the sum of the thicknesses of the N-type charge generation layer, the P-type charge generation layer, and the second hole transport layer is less than the thickness of the first hole transport layer. The light emitting device according to claim 3 , wherein: The first light-emitting unit also includes a first optical auxiliary layer located between the first hole transport layer and the first light-emitting layer, and the second light-emitting unit also includes a second optical auxiliary layer located between the second hole transport layer and the second light-emitting layer, and the thickness of the first optical auxiliary layer is greater than or equal to the thickness of the second optical auxiliary layer.

5. The light emitting device according to any one of claims 2 to 4, wherein: The first light emitting unit further includes: a hole injection layer, located between the anode and the first light-emitting layer; a first electron transport layer, located between the first light-emitting layer and the second light-emitting layer; and The first hole blocking layer is located between the first electron transport layer and the first light-emitting layer. The light emitting device according to claim 5 , wherein: The hole injection layer and the P-type charge generation layer both include a host material and a guest material, the guest material of the hole injection layer is the same as the guest material of the P-type charge generation layer, and a first ratio of the mass of the guest material in the hole injection layer to the sum of the masses of the host material and the guest material is less than a second ratio of the mass of the guest material in the P-type charge generation layer to the sum of the masses of the host material and the guest material.

7. The light emitting device according to claim 5 or 6, wherein: The electrical conductivity of the hole injection layer is lower than that of the P-type charge generation layer.

8. The light emitting device according to any one of claims 5 to 7, wherein: the thickness of the hole injection layer is less than or equal to the sum of the thickness of the first electron transport layer and the thickness of the first hole blocking layer; or The thickness of the hole injection layer is greater than the sum of the thickness of the first electron transport layer and the thickness of the first hole blocking layer.

9. The light emitting device according to any one of claims 1 to 8, further comprising a cathode located on a side of the second light emitting unit away from the anode, in, The distance between the second light-emitting layer and the cathode is a third distance, and the first distance is greater than or equal to the third distance.

10. The light emitting device according to claim 9, wherein The third distance is greater than or equal to the second distance.

11. The light emitting device according to claim 9 or 10, wherein: The distance between the second light-emitting layer and the anode is a fourth distance, the distance between the anode and the cathode is a fifth distance, and a ratio of the fourth distance to the fifth distance is 70% to 85%.

12. The light emitting device according to claim 9 or 10, wherein: The distance between the anode and the cathode is a fifth distance, and a ratio of the first distance to the fifth distance is 36% to 50%.

13. The light emitting device according to claim 9 or 10, wherein: The distance between the anode and the cathode is a fifth distance, The first light-emitting layer and the second light-emitting layer both emit red light, and a ratio of the second distance to the fifth distance is 20% to 30%; or The first light-emitting layer and the second light-emitting layer both emit green light, and a ratio of the second distance to the fifth distance is 25% to 35%; or The first light-emitting layer and the second light-emitting layer both emit blue light, and a ratio of the second distance to the fifth distance is 31% to 45%.

14. The light emitting device according to any one of claims 9 to 13, wherein: The second light emitting unit further includes: an electron injection layer, located between the cathode and the second light-emitting layer; a second electron transport layer, located between the electron injection layer and the second light-emitting layer; and The second hole blocking layer is located between the second electron transport layer and the second light-emitting layer.

15. The light emitting device according to any one of claims 1 to 14, wherein: The first light-emitting unit further includes a third light-emitting layer and a fifth light-emitting layer, wherein the first light-emitting layer, the third light-emitting layer, and the fifth light-emitting layer are separated from each other and emit light of different colors; The second light-emitting unit further includes a fourth light-emitting layer and a sixth light-emitting layer, wherein the second light-emitting layer, the fourth light-emitting layer, and the sixth light-emitting layer are separated from each other and emit light of different colors; The first light-emitting layer and the second light-emitting layer emit light of a first color and their orthographic projections on the anode at least partially overlap, the third light-emitting layer and the fourth light-emitting layer emit light of a second color and their orthographic projections on the anode at least partially overlap, and the fifth light-emitting layer and the sixth light-emitting layer emit light of a third color and their orthographic projections on the anode at least partially overlap.

16. A light emitting device comprising: anode; a first light-emitting unit, located on the anode and comprising a first light-emitting layer; a second light-emitting unit, located on a side of the first light-emitting unit away from the anode and comprising a second light-emitting layer; and a cathode, located on a side of the second light-emitting unit away from the anode, The first light-emitting layer and the second light-emitting layer emit light of the same color, the distance between the anode and the first light-emitting layer is a first distance, the distance between the first light-emitting layer and the second light-emitting layer is a second distance, the distance between the second light-emitting layer and the cathode is a third distance, the first distance is greater than or equal to the third distance, and the third distance is greater than or equal to the second distance.

17. A display panel comprising: substrate; as well as A plurality of light emitting devices as claimed in any one of claims 1 to 15 or a plurality of light emitting devices as claimed in claim 1 The light-emitting device described in claim 16, wherein the plurality of light-emitting devices are arranged on the substrate.

18. The display panel according to claim 17, further comprising a plurality of spacer columns, in, The light emitting device further includes a charge generation layer located between the first light emitting unit and the second light emitting unit, the charge generation layer being shared by the plurality of light emitting devices, and The plurality of isolation pillars are located on one side of the substrate where the plurality of light-emitting devices are arranged, and at least a portion of the charge generation layer located between the plurality of light-emitting devices is isolated by the plurality of isolation pillars.

19. The display panel according to claim 18, wherein: The first light-emitting unit further includes a third light-emitting layer and a fifth light-emitting layer, wherein the first light-emitting layer, the third light-emitting layer, and the fifth light-emitting layer are separated from each other and emit light of different colors; The second light-emitting unit further includes a fourth light-emitting layer and a sixth light-emitting layer, wherein the second light-emitting layer, the fourth light-emitting layer, and the sixth light-emitting layer are separated from each other and emit light of different colors; The first light-emitting layer and the second light-emitting layer emit light of a first color, and their orthographic projections on the anode at least partially overlap, the third light-emitting layer and the fourth light-emitting layer emit light of a second color, and their orthographic projections on the anode at least partially overlap, and the fifth light-emitting layer and the sixth light-emitting layer emit light of a third color, and their orthographic projections on the anode at least partially overlap; The light-emitting device includes a plurality of sub-light-emitting devices, the sub-light-emitting devices including a first sub-light-emitting device, a second sub-light-emitting device, and a third sub-light-emitting device, the first sub-light-emitting device including the first light-emitting layer and the second light-emitting layer, the second sub-light-emitting device including the third light-emitting layer and the fourth light-emitting layer, and the third sub-light-emitting device including the fifth light-emitting layer and the sixth light-emitting layer; and The charge generation layer is also shared by the plurality of sub-light-emitting devices, and portions of the charge generation layer located between the plurality of sub-light-emitting devices are also partitioned by the plurality of isolation pillars.

20. The display panel according to claim 18 or 19, wherein: The light emitting device further includes a cathode located on a side of the second light emitting unit away from the anode. The distance between the anode and the cathode is a fifth distance, and a ratio of the fifth distance to the thickness of the isolation column is 15% to 40%.

21. An electronic device comprising the display panel according to any one of claims 17 to 20.

Images