Light emitting device and display panel

Abstract

The invention provides a light-emitting device and a display panel, and belongs to the technical field of display. According to the light-emitting device, the resonance microcavity is formed between the anode and the cathode; a first light-emitting unit of the light-emitting device comprises a first light-emitting layer and a first electron blocking layer; a second light-emitting unit of the light-emitting device comprises a second light-emitting layer and a second electron blocking layer; the first light-emitting layer is arranged at a first antinode point of a resonance wave of the resonance microcavity; the second light-emitting layer is arranged at a second antinode point of the resonance wave of the resonance microcavity; the sum of the thickness of the first light-emitting layer and the thickness of the first electron blocking layer is a first thickness; the sum of the thickness of the second light-emitting layer and the thickness of the second electron blocking layer is a second thickness; the light-emitting device is a red light-emitting device, and the ratio of the first thickness to the second thickness is 0.6-1.2; or, the light-emitting device is a green light-emitting device, and the ratio of the first thickness to the second thickness is 0.8-1.2; or the light-emitting device is a blue light-emitting device, and the ratio of the first thickness to the second thickness ranges from 0.8 to 1.2.

Description

Technical Field

[0001] The present disclosure belongs to the technical fields of organic semiconductors and display technologies, and particularly relates to a light-emitting device and a display panel. Background Art

[0002] An organic light-emitting diode (OLED) is a light-emitting device that uses an organic solid semiconductor as a light-emitting material, and has the characteristics of self-luminescence, no need for a backlight source, thin panel thickness, and light weight. At the same time, the OLED also has many advantages such as a wide viewing angle, high contrast, fast response, a wide working temperature range, and flexibility.

[0003] In order to obtain a higher current efficiency, multiple light-emitting units can be stacked, and adjacent light-emitting units are connected through a charge generation layer (CGL). Usually, an OLED with multiple stacked light-emitting units is called a tandem OLED (or a Tandem device). The tandem OLED has broad application prospects due to its advantages such as higher efficiency and longer lifespan compared to traditional OLEDs. Summary of the Invention

[0004] The present disclosure aims to solve at least one of the technical problems existing in the prior art, and provides a light-emitting device and a display panel.

[0005] In a first aspect, the technical solution adopted to solve the technical problems of the present disclosure is a light-emitting device, including an anode, a cathode, a plurality of the light-emitting units disposed between the anode and the cathode, and a charge generation and separation unit disposed between adjacent light-emitting units; a resonant microcavity is formed between the anode and the cathode; the resonant microcavity includes a plurality of antinode points;

[0006] The plurality of light-emitting units at least includes a first light-emitting unit and a second light-emitting unit, and the first light-emitting unit is closer to the anode than the second light-emitting unit;

[0007] The first light-emitting unit includes a first light-emitting layer and a first electron blocking layer disposed on a side of the first light-emitting layer close to the anode; the second light-emitting unit includes a second light-emitting layer and a second electron blocking layer disposed on a side of the second light-emitting layer close to the anode;

[0008] The first light-emitting layer is disposed at a first antinode point of the resonant wave of the resonant microcavity; the second light-emitting layer is disposed at a second antinode point of the resonant wave of the resonant microcavity;

[0009] The sum of the thickness of the first light-emitting layer and the thickness of the first electron blocking layer is denoted as the first thickness; the sum of the thickness of the second light-emitting layer and the thickness of the second electron blocking layer is denoted as the second thickness; the light-emitting device is a red light-emitting device, and the ratio of the first thickness to the second thickness is between 0.6 and 1.2; or, the light-emitting device is a green light-emitting device, and the ratio of the first thickness to the second thickness is between 0.8 and 1.2; or, the light-emitting device is a blue light-emitting device, and the ratio of the first thickness to the second thickness is between 0.8 and 1.2.

[0010] In some embodiments, the distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the cavity length of the resonant microcavity; the distance between the third surface of the first light-emitting layer close to the anode and the first surface is the first distance;

[0011] The light-emitting device is a red light-emitting device, and the ratio of the first distance to the cavity length of the microcavity is between 0.15 and 0.4; or, the light-emitting device is a green light-emitting device, and the ratio of the thickness of the first distance to the cavity length of the microcavity is between 0.1 and 0.3; or, the light-emitting device is a blue light-emitting device, and the ratio of the thickness of the first distance to the cavity length of the microcavity is between 0.1 and 0.3.

[0012] In some embodiments, the distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the cavity length of the resonant microcavity; the distance between the fourth surface of the second light-emitting layer close to the anode and the first surface is the second distance;

[0013] The light-emitting device is a red light-emitting device, and the ratio of the second distance to the cavity length of the microcavity is between 0.5 and 0.7; or, the light-emitting device is a green light-emitting device, and the ratio of the thickness of the second distance to the cavity length of the microcavity is between 0.55 and 0.75; or, the light-emitting device is a blue light-emitting device, and the ratio of the thickness of the second distance to the cavity length of the microcavity is between 0.6 and 0.8.

[0014] In some embodiments, the distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the cavity length of the resonant microcavity; the thickness of the charge generation and separation unit is denoted as the third thickness;

[0015] The light-emitting device is a red light-emitting device, and the ratio of the third thickness to the microcavity length is between 0.07 and 0.12; or, the light-emitting device is a green light-emitting device, and the ratio of the third thickness to the microcavity length is between 0.09 and 0.15; or, the light-emitting device is a blue light-emitting device, and the ratio of the third thickness to the microcavity length is between 0.12 and 0.18.

[0016] In some embodiments, the light-emitting device is a red light-emitting device, and the thickness of the first electron blocking layer is greater than the thickness of the second electron blocking layer.

[0017] In some embodiments, an exciton trapping agent is doped in the material of the second electron blocking layer; the doping concentration of the exciton trapping agent is between 0.5% and 2%.

[0018] In some embodiments, the HOMO energy level of the exciton trapping agent is shallower than the HOMO energy level of the second electron blocking layer; the absolute value of the difference between the HOMO energy level of the exciton trapping agent and the HOMO energy level of the second electron blocking layer is greater than or equal to 0.2 eV.

[0019] In some embodiments, the structural general formula (I) of the material of the exciton trapping agent is as follows:

[0020]

[0021] Wherein, Ra and Rb each independently represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group; Rc, Rd, Re and Rf each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

[0022] In some embodiments, the structure of the material of the exciton trapping agent includes any one of the following:

[0023]

[0024]

[0025]

[0026] In some embodiments, the material of the exciton trapping agent is the same as the red host material of the second light-emitting layer.

[0027] In some embodiments, the light-emitting device is a red light-emitting device, and the thickness of the second light-emitting layer is greater than or equal to the thickness of the first light-emitting layer.

[0028] In some embodiments, the material of the second light-emitting layer includes a red host material and a red guest material; the red host material includes a P-type material and an N-type material; the doping concentration of the P-type material is greater than or equal to the doping concentration of the N-type material.

[0029] In some embodiments, the material of the first light-emitting layer is different from the material of the second light-emitting layer; the mobility of the second light-emitting layer is greater than the mobility of the first light-emitting layer.

[0030] In some embodiments, the charge generation and separation unit includes an N-type charge generation layer and a P-type charge generation layer arranged in sequence along the direction from the anode to the cathode.

[0031] The first light-emitting unit further includes a hole injection layer disposed on the anode near the first electron blocking layer, a first hole transport layer disposed on one side of the hole injection layer near the first electron blocking layer, a first hole blocking layer disposed on one side of the first light-emitting layer near the N-type charge generation layer, and a first electron transport layer disposed on one side of the first hole blocking layer near the N-type charge generation layer.

[0032] The second light-emitting unit further includes an electron injection layer, a second electron transport layer, and a second hole blocking layer arranged in sequence on the cathode along the direction from the cathode to the second light-emitting layer, and a second hole transport layer disposed between the second electron blocking layer and the P-type charge generation layer.

[0033] In some embodiments, the absolute value of the difference between the HOMO energy level of the P-type charge generation layer and the HOMO energy level of the second hole transport layer is less than or equal to 0.3 eV; the absolute value of the difference between the lowest unoccupied molecular orbital LUMO energy level of the N-type charge generation layer and the LUMO energy level of the first hole blocking layer is less than or equal to 0.5 eV.

[0034] The absolute value of the difference between the HOMO energy level of the first hole transport layer and the HOMO energy level of the first electron blocking layer ranges between 0.1 eV and 0.4 eV; the absolute value of the difference between the HOMO energy level of the second hole transport layer and the HOMO energy level of the second electron blocking layer ranges between 0.1 eV and 0.4 eV.

[0035] In some embodiments, the material of the first hole transport layer is different from the material of the second hole transport layer; the mobility of the first hole transport layer is greater than the mobility of the second hole transport layer.

[0036] In some embodiments, the P-type charge generation layer is doped with a material represented by structural formula (II) or structural formula (III).

[0037] The general structural formula (II) is as follows:

[0038]

[0039] Wherein, A1 - A6 each independently represent a substituted or unsubstituted halogen, a substituted or unsubstituted cyano group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; when A1 - A6 each independently represent an aryl group as a substituent, the aryl group is substituted by an electron-withdrawing group; A represents a three-membered ring, a four-membered ring, a five-membered ring, or a six-membered ring.

[0040] The general structural formula (III) is as follows:

[0041]

[0042] Wherein, X1 and X2 each independently represent one of C, N, and Si; Y1 and Y2 each independently represent one of O, N, and S; Ar1 - Ar4 each independently represent a substituted or unsubstituted halogen, a substituted or unsubstituted cyano group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted adamantane group, or a substituted or unsubstituted heteroaryl group; R1 and R2 each independently represent deuterium, a halogen group, a cyano group, a substituted or unsubstituted heteroaryl group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 18 carbon atoms, an arylthio group having 6 to 18 carbon atoms, a phosphoxy group having 6 to 24 carbon atoms, or a substituted or unsubstituted alkylsulfonyl group having 6 to 18 carbon atoms; a and b each independently represent an integer from 1 to 5.

[0043] In some embodiments, the N-type host material of the N-type charge generation layer is a material represented by the general structural formula (IV);

[0044] The general structural formula (IV) is as follows:

[0045]

[0046] Wherein, X1-X4 each independently represent N or C(R1), and each of X1-X4 independently contains at least 2 Ns; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-C60 alkynyl, substituted or unsubstituted C1-C60 alkoxy, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C1-C10 heterocycloalkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocycloalkenyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C6-C60 arylthio, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group; Ar1, Ar2, Ar3, Ar4 are the same or different, and each independently represents one selected from the following: hydrogen, deuterium, tritium, halogen, cyano, nitro, C6-C60 aryl, C2-C60 heterocyclic group containing at least one heteroatom from O, N, S, Si and P, C3-C60 aliphatic ring, fused ring group of C6-C60 aromatic ring, C1-C50 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C30 alkoxy, C6-C30 aryloxy, C3-C60 alkylsilyl, C18-C60 arylsilyl, C8-C60 alkylarylsilyl.

[0047] In some embodiments, the distance between the first surface of the anode adjacent to the cathode and the second surface of the cathode adjacent to the anode is the cavity length of the resonant microcavity;

[0048] The light-emitting device is a red light-emitting device, and the range of the cavity length is between 2500 Å and 3000 Å; or, the light-emitting device is a green light-emitting device, and the range of the cavity length is between 2500 Å and 2600 Å; or, the light-emitting device is a blue light-emitting device, and the range of the cavity length is between 1500 Å and 2000 Å.

[0049] In some embodiments, the materials of the first light-emitting layer and the second light-emitting layer are the same;

[0050] The material of the first light-emitting layer includes a light-emitting host material and a light-emitting guest material; the light-emitting host material is an exciplex.

[0051] In some embodiments, the light-emitting device is a blue light-emitting device;

[0052] The triplet energy level of the first hole blocking layer is greater than that of the blue host material of the first light-emitting material; the triplet energy level of the first electron blocking layer is greater than that of the blue host material of the first light-emitting material.

[0053] In a second aspect, embodiments of the present disclosure further provide a display panel, which includes the light-emitting device according to any one of the first aspect.

[0054] In some embodiments, the display panel further includes a partition structure disposed between two adjacent light-emitting devices; the two light-emitting devices emit light of different colors, and the charge generation separation units of the two light-emitting devices are blocked at the position of each partition structure. Description of the Drawings

[0055] Figure 1 Schematic diagram of a tandem OLED.

[0056] Figure 2 Schematic diagram of the light-emitting principle of a tandem OLED.

[0057] Figure 3 Schematic diagram of the light-emitting device provided by an embodiment of the present disclosure.

[0058] Figure 4 Schematic diagram of the structural dimensions in the light-emitting device provided by an embodiment of the present disclosure.

[0059] Figure 5 Schematic diagram of the comparison of the energy level relationships between the red light-emitting device and the green light-emitting device provided by an embodiment of the present disclosure.

[0060] Figure 6 Schematic diagram of multiple light-emitting devices in the display panel provided by an embodiment of the present disclosure.

[0061] Figure 7 Schematic diagram of the partition structure in Example 1 of the display panel provided by an embodiment of the present disclosure.

[0062] Figure 8 Schematic diagram of the partition structure in Example 2 of the display panel provided by an embodiment of the present disclosure.

[0063] Figure 9 Schematic diagram of the partition structure in Example 3 of the display panel provided by an embodiment of the present disclosure.

[0064] Figure 10 For Figure 9 The enlarged view of the partition structure in. Detailed Embodiments

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part rather than all of the embodiments of the present disclosure. Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure belongs. The "first", "second", and similar terms used in the present disclosure do not indicate any order, quantity, or importance, but are only used to distinguish different components. The terms such as "upper", "lower", "left", and "right" are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly. The "multiple" or "several" mentioned in the present disclosure refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0066] Figure 1 It is a schematic diagram of a tandem OLED. Figure 2 It is a schematic diagram of the light emission principle of a tandem OLED. As Figure 1 and Figure 2 shown, the tandem OLED includes an anode 1, a cathode 2, a plurality of light-emitting units disposed between the anode 1 and the cathode 2, and a charge generation and separation unit 4 disposed between adjacent light-emitting units. In the present disclosure, two light-emitting units are taken as an example, denoted as a first light-emitting unit 31 and a second light-emitting unit 32 respectively. The first light-emitting unit 31 includes a first light-emitting layer EML1 and functional layers located on both sides of the first light-emitting layer EML1 and used for assisting the transport of carriers; the second light-emitting unit 32 includes a second light-emitting layer EML2 and functional layers located on both sides of the second light-emitting layer EML2 and used for assisting the transport of carriers. The charge generation and separation unit 4 is used to generate holes and electrons (collectively referred to as carriers) and separate the two and inject them respectively into the second light-emitting layer EML2 side and the first light-emitting layer EML1 side. During this process, the functional layers for assisting the transport of carriers can better transport the carriers, so that the carriers can be fully recombined in the light-emitting layer EML. In the tandem OLED, the three processes of efficiently generating charges, quickly transporting charges, and effectively injecting charges are all indispensable and have a significant impact on the performance of the device. Therefore, how to reasonably match the light-emitting units and the charge generation and separation unit 4 to ensure the efficient generation, injection, and transport of carriers has become a difficult problem to be solved urgently in the fields of organic semiconductors and display technologies.

[0067] In view of this, the embodiments of the present disclosure provide a light-emitting device. Figure 3 It is a schematic diagram of the light-emitting device provided by the embodiments of the present disclosure. Figure 4Schematic diagram of the structural dimensions in the light-emitting device provided by the embodiments of the present disclosure.

[0068] As Figure 3 shown, the light-emitting device includes an anode 1, a cathode 2, a plurality of light-emitting units disposed between the anode 1 and the cathode 2, and a charge generation separation unit 4 disposed between adjacent light-emitting units. The plurality of light-emitting units at least include a first light-emitting unit 31 and a second light-emitting unit 32, and the first light-emitting unit 31 is closer to the anode 1 than the second light-emitting unit 32. In the present disclosure, two light-emitting units are taken as an example, and actually, there may be more than two light-emitting units, and a charge generation separation unit 4 is disposed between adjacent light-emitting units.

[0069] As Figure 4 shown, a resonant microcavity is formed between the anode 1 and the cathode 2. The resonant microcavity includes a plurality of antinode points. Exemplarily, the light-emitting device of the present disclosure is an OLED device. Since the light-emitting device of the present disclosure includes a plurality of light-emitting units, that is, the light-emitting device of the present disclosure is a tandem OLED. Each light-emitting unit in the tandem OLED has its own emission layer EML. The first light-emitting unit 31 has a first emission layer EML1, and the second light-emitting unit 32 has a second emission layer EML2. The first emission layer EML1 is driven by holes and electrons generated by the anode 1 and the charge generation separation unit 4 respectively, and the second light-emitting unit 32 is driven by holes and electrons generated by the charge generation separation unit 4 and the cathode 2 respectively. Therefore, the tandem OLED forms a plurality of optical cavities, which are collectively referred to as resonant microcavities in the present disclosure. Each optical cavity generates resonance, thereby generating a plurality of antinode points. In the present disclosure, the first emission layer EML1 is disposed at the first antinode point of the resonant wave of the resonant microcavity, and the second emission layer EML2 is disposed at the second antinode point of the resonant wave of the resonant microcavity. The resonant microcavity can enhance the light field intensity of a specific wavelength, increase the photon density near the antinode point of the emission layer EML, thereby improving the light-emitting efficiency; at the same time, the enhanced light field intensity can reduce the driving voltage required to reach the same brightness, thereby reducing the power consumption; the light field intensity near the antinode point is the largest, which helps more photons to escape from the device, reduces internal losses, and improves the light extraction efficiency; in addition, the enhanced light field intensity can reduce the driving voltage required to reach the same brightness, thereby reducing the power consumption and improving the performance of the tandem OLED device.

[0070] The first light-emitting unit 31 further includes a first electron blocking layer EBL1 disposed on the side of the first light-emitting layer EML1 close to the anode 1; the second light-emitting unit 32 further includes a second electron blocking layer EBL2 disposed on the side of the second light-emitting layer EML2 close to the anode 1; wherein, the sum of the thickness of the first light-emitting layer EML1 and the thickness of the first electron blocking layer EBL1 is denoted as the first thickness L1; the sum of the thickness of the second light-emitting layer EML2 and the thickness of the second electron blocking layer EBL2 is denoted as the second thickness L2; the light-emitting device is a red light-emitting device R, and the ratio of the first thickness L1(R) to the second thickness L2(R) is between 0.6 and 1; or, the light-emitting device is a green light-emitting device G, and the ratio of the first thickness L1(G) to the second thickness L2(G) is between 0.8 and 1.2; or, the light-emitting device is a blue light-emitting device B, and the ratio of the first thickness L1(B) to the second thickness L2(B) is between 0.8 and 1.2. For the convenience of understanding, refer to the following relational expression (1).

[0071] Relational expression (1):

[0072] In the embodiments of the present disclosure, by adjusting the thicknesses of the light-emitting layer EML and the electron blocking layer EBL, the light-emitting position is optimized, and on the premise that the light-emitting layer EML is located near the antinode point (microcavity enhancement region), the superposition effect of the upper and lower light-emitting layers EML is further improved. For example, by setting the ratio of the total thickness (the first thickness L1) of the first light-emitting layer EML1 and the first electron blocking layer EBL1 of the red light-emitting device R to the total thickness (the second thickness L2) of the second light-emitting layer EML2 and the second electron blocking layer EBL2, and ensuring that the ratio is between 0.6 and 1.2, the superposition light-emitting effect of the first light-emitting layer EML1 and the second light-emitting layer EML2 of the red light-emitting device R can be improved. By setting the ratio of the total thickness (the first thickness L1) of the first light-emitting layer EML1 and the first electron blocking layer EBL1 of the green light-emitting device G to the total thickness (the second thickness L2) of the second light-emitting layer EML2 and the second electron blocking layer EBL2, and ensuring that the ratio is between 0.8 and 1.2, the superposition light-emitting effect of the first light-emitting layer EML1 and the second light-emitting layer EML2 of the green light-emitting device G can be improved. By setting the ratio of the total thickness (the first thickness L1) of the first light-emitting layer EML1 and the first electron blocking layer EBL1 of the blue light-emitting device B to the total thickness (the second thickness L2) of the second light-emitting layer EML2 and the second electron blocking layer EBL2, and ensuring that the ratio is between 0.8 and 1.2, the superposition light-emitting effect of the first light-emitting layer EML1 and the second light-emitting layer EML2 of the blue light-emitting device B can be improved.

[0073] Exemplarily, the ratio of the first thickness L1 to the second thickness L2 of the red light-emitting device R is 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2. Of course, these are only seven cases for illustration. The above thickness ratio of the red light-emitting device R is not limited to the enumerated cases. Any value between 0.6 and 1.2 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0074] Exemplarily, the ratio of the first thickness L1 to the second thickness L2 of the green light-emitting device G is 0.8, 0.9, 1.0, 1.1, or 1.2. Of course, these are only five cases for illustration. The above thickness ratio of the green light-emitting device G is not limited to the enumerated cases. Any value between 0.8 and 1.2 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0075] Exemplarily, the ratio of the first thickness L1 to the second thickness L2 of the blue light-emitting device B is 0.8, 0.9, 1.0, 1.1, or 1.2. Of course, these are only five cases for illustration. The above thickness ratio of the blue light-emitting device B is not limited to the enumerated cases. Any value between 0.8 and 1.2 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0076] In some embodiments, as Figure 4 shown, the distance between the first surface of the anode 1 close to the cathode 2 and the second surface of the cathode 2 close to the anode 1 is the microcavity length L of the resonant microcavity. The light-emitting device is a red light-emitting device R, and the range of the microcavity length L(R) is between 2500 Å and 3000 Å; or, the light-emitting device is a green light-emitting device G, and the range of the microcavity length L(G) is between 2500 Å and 2600 Å; or, the light-emitting device is a blue light-emitting device B, and the range of the microcavity length L(B) is between 1500 Å and 2000 Å. For easy understanding, refer to the following relation (two).

[0077] Relation (two):

[0078] In this embodiment, by adjusting the microcavity length of the resonant microcavity, the total thickness of the tandem OLED device is optimized to ensure that the light-emitting positions of the red light-emitting device R, the green light-emitting device G, or the blue light-emitting device B are all near their respective antinode points (microcavity enhancement regions), thereby improving the light extraction efficiency of the tandem OLED device.

[0079] In some embodiments, as Figure 4As shown, the distance between the third surface and the first surface of the first emitting layer EML1 close to the anode 1 is the first distance L3; the light-emitting device is a red light-emitting device R, and the ratio of the first distance L3(R) to the microcavity length L(R) is between 0.15 and 0.4; alternatively, the light-emitting device is a green light-emitting device G, and the ratio of the thickness of the first distance L3(G) to the microcavity length L(G) is between 0.1 and 0.3; alternatively, the light-emitting device is a blue light-emitting device B, and the ratio of the thickness of the first distance L3(B) to the microcavity length L(B) is between 0.1 and 0.3. For the convenience of understanding, reference can be made to the following relational expression (III).

[0080] Relational expression (III):

[0081] Exemplarily, the ratio of the first distance L3(R) of the red light-emitting device R to the microcavity length L is 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4. Of course, these are only six exemplary cases, and the above ratio of the red light-emitting device R is not limited to the listed cases. Any value within the range of 0.15 to 0.4 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0082] Exemplarily, the ratio of the first distance L3(G) of the green light-emitting device G to the microcavity length L is 0.1, 0.15, 0.2, 0.25 or 0.3. Of course, these are only five exemplary cases, and the above ratio of the green light-emitting device G is not limited to the listed cases. Any value within the range of 0.1 to 0.3 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0083] Exemplarily, the ratio of the first distance L3(B) of the blue light-emitting device B to the microcavity length L is 0.1, 0.15, 0.2, 0.25 or 0.3. Of course, these are only five exemplary cases, and the above ratio of the blue light-emitting device B is not limited to the listed cases. Any value within the range of 0.1 to 0.3 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0084] In this embodiment, by adjusting the first distance L3 between the first emitting layer EML1 and the anode 1, the position of the first emitting layer EML1 is optimized to ensure that the first emitting layer EML1 is near the antinode point (microcavity enhancement region), thereby improving the light extraction efficiency of the tandem OLED device.

[0085] In some embodiments, such as Figure 4As shown, the distance between the fourth surface and the first surface of the second emitting layer EML2 close to the anode 1 is the second distance L4; the light-emitting device is a red light-emitting device R, and the ratio of the second distance L4(R) to the microcavity length L(R) is between 0.5 and 0.7; alternatively, the light-emitting device is a green light-emitting device G, and the ratio of the thickness of the second distance L4(G) to the microcavity length L(R) is between 0.55 and 0.75; alternatively, the light-emitting device is a blue light-emitting device B, and the ratio of the thickness of the second distance L4(B) to the microcavity length L(R) is between 0.6 and 0.8. For the convenience of understanding, reference can be made to the following relational expression (IV).

[0086] Relational expression (IV):

[0087] Exemplarily, the ratio of the second distance L4(R) of the red light-emitting device R to the microcavity length L is 0.5, 0.55, 0.6, 0.65, or 0.7. Of course, these are only five exemplary cases, and the above ratio of the red light-emitting device R is not limited to the enumerated cases. Any value within the range of 0.5 to 0.7 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0088] Exemplarily, the ratio of the second distance L4(G) of the green light-emitting device G to the microcavity length L is 0.55, 0.6, 0.65, 0.7, or 0.75. Of course, these are only five exemplary cases, and the above ratio of the green light-emitting device G is not limited to the enumerated cases. Any value within the range of 0.55 to 0.75 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0089] Exemplarily, the ratio of the second distance L4(B) of the blue light-emitting device B to the microcavity length L is 0.6, 0.65, 0.7, 0.75, or 0.8. Of course, these are only five exemplary cases, and the above ratio of the blue light-emitting device B is not limited to the enumerated cases. Any value within the range of 0.6 to 0.8 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0090] In this embodiment, by adjusting the second distance L4 between the second emitting layer EML2 and the anode 1, the position of the second emitting layer EML2 is optimized to ensure that the second emitting layer EML2 is near the antinode point (microcavity enhancement region), thereby improving the light extraction efficiency of the tandem OLED device.

[0091] In some embodiments, such as Figure 4As shown, the thickness of the charge generation and separation unit 4 is denoted as the third thickness L5; the light-emitting device is a red light-emitting device R, and the ratio of the third thickness L5(R) to the microcavity length L(R) is between 0.07 and 0.12; alternatively, the light-emitting device is a green light-emitting device G, and the ratio of the third thickness L5(G) to the microcavity length L(G) is between 0.09 and 0.15; alternatively, the light-emitting device is a blue light-emitting device B, and the ratio of the third thickness L5(B) to the microcavity length L(B) is between 0.12 and 0.18. For the convenience of understanding, reference can be made to the following relational expression (five).

[0092] Relational expression (five):

[0093] Exemplarily, the ratio of the third thickness L5(R) of the red light-emitting device R to the microcavity length L is 0.07, 0.08, 0.09, 0.1, 0.11 or 0.12. Of course, these are only six exemplary cases, and the above ratio of the red light-emitting device R is not limited to the enumerated cases. Any value within the range of 0.07 to 0.12 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0094] Exemplarily, the ratio of the third thickness L5(G) of the green light-emitting device G to the microcavity length L is 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15. Of course, these are only seven exemplary cases, and the above ratio of the green light-emitting device G is not limited to the enumerated cases. Any value within the range of 0.09 to 0.15 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0095] Exemplarily, the ratio of the third thickness L5(B) of the blue light-emitting device B to the microcavity length L is 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 or 0.18. Of course, these are only seven exemplary cases, and the above ratio of the blue light-emitting device B is not limited to the enumerated cases. Any value within the range of 0.12 to 0.18 falls within the protection scope of the present disclosure, and no further examples will be given here.

[0096] In this embodiment, by adjusting the position of the charge generation and separation unit 4, when preparing the partition structure in the display panel (refer to the structure description of the subsequent display panel, which will not be elaborated here), it is possible to integrally partition the charge generation and separation units 4 of adjacent light-emitting devices while ensuring the overall continuity of the cathode 2, thereby improving the crosstalk phenomenon between different pixels, reducing the voltage of the device, and ensuring that the series OLED has relatively low power consumption.

[0097] In some embodiments, the light-emitting device is a red light-emitting device R, and the thickness of the first electron blocking layer EBL1 is greater than the thickness of the second electron blocking layer EBL2.

[0098] This embodiment improves the tandem red OLED. The first electron blocking layer EBL1 is disposed between the first emitting layer EML1 and the anode 1, mainly for blocking electrons entering the first emitting layer EML1 from the anode 1 side; the second electron blocking layer EBL2 is disposed between the second emitting layer EML2 and the charge generation and separation unit 4, mainly for blocking electrons entering the second emitting layer EML2 from the charge generation and separation unit 4 side. Since the ability of the charge generation and separation unit 4 to generate holes and electrons is stronger than that of the anode 1 to generate holes and the cathode 2 to generate electrons, increasing the thickness of the first electron blocking layer EBL1 in this embodiment can help block excess electrons from entering the first emitting layer EML1, thereby helping to make the carrier distribution on the first emitting layer EML1 uniform, ensuring that the exciton recombination region is located at the center of the first emitting layer EML1, and being beneficial to improving the overall luminous efficiency of the tandem red OLED.

[0099] Optionally, the material of the second electron blocking layer EBL2 is doped with an exciton trapping agent. The so-called "exciton trapping agent" is a material that can trap holes. The exciton trapping agent can trap excess holes in the electron blocking layer EBL to prevent too many holes from entering the emitting layer EML and causing a significant attenuation of the device efficiency.

[0100] Optionally, the doping concentration of the exciton trapping agent is between 0.5% and 2%. The "doping concentration" here refers to the mass ratio, for example, the mass ratio of the exciton trapping agent to the material of the electron blocking layer EBL.

[0101] Optionally, the HOMO energy level of the exciton trapping agent is shallower than the HOMO energy level of the second electron blocking layer EBL2, which can form a good hole trapping effect in the second electron blocking layer EBL2, thereby helping to make the carrier distribution on the second emitting layer EML2 uniform, ensuring that the exciton recombination region is located at the center of the second emitting layer EML2, and being beneficial to improving the overall luminous efficiency of the tandem red OLED.

[0102] Optionally, the absolute value of the difference between the HOMO energy level of the exciton trapping agent and the HOMO energy level of the second electron blocking layer EBL2 is greater than or equal to 0.2 eV, that is, |HOMO (exciton trapping agent) - HOMO (EBL2)| ≥ 0.2 eV, which can form a good hole trapping effect in the second electron blocking layer EBL2.

[0103] In this embodiment, the thickness of the first electron blocking layer EBL1 of the red light-emitting device R is greater than that of the second electron blocking layer EBL2. At the same time, the second electron blocking layer EBL2 is doped with an exciton trapping agent, and the HOMO energy level of the exciton trapping agent is shallower than that of the second electron blocking layer EBL2. This can evenly distribute the charges in both the first light-emitting layer EML1 and the second light-emitting layer EML2, ensure that the exciton recombination centers of both are close to the center of the light-emitting layer EML, avoid defects such as color bleeding and crosstalk between the first light-emitting layer EML1 and the second light-emitting layer EML2, and is beneficial to improving the overall luminous efficiency and lifespan of the tandem red OLED.

[0104] Optionally, the structural general formula (I) of the material of the exciton trapping agent is as follows.

[0105] Structural general formula (I):

[0106] Wherein, Ra and Rb each independently represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group; Rc, Rd, Re, and Rf each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; N represents a nitrogen atom; Ir represents an iridium atom; and O represents an oxygen atom.

[0107] Exemplarily, the structure of the material of the exciton trapping agent includes any one of the following (1-1 to 1-12):

[0108]

[0109]

[0110] Optionally, in addition to the material corresponding to the above structural general formula (I), the material of the exciton trapping agent can also be the same as the red guest material RD of the second light-emitting layer EML2. The red guest material RD can be referred to the following description and will not be elaborated here.

[0111] In some embodiments, the light-emitting device is a red light-emitting device R, and the thickness of the second light-emitting layer EML2 is greater than or equal to that of the first light-emitting layer EML1.

[0112] Optionally, the thickness of the second light-emitting layer EML2 is greater than that of the first light-emitting layer EML1. In this embodiment, by increasing the thickness of the second light-emitting layer EML2, the exciton recombination region of the second light-emitting layer EML2 is broadened, thereby improving the degradation of the high-energy state excitons on the materials at the interface, and further improving the lifespan of the device.

[0113] The materials of the first light-emitting layer EML1 and the second light-emitting layer EML2 can be the same or different.

[0114] Optionally, the materials of the first emitting layer EML1 and the second emitting layer EML2 are the same. The material of the second emitting layer EML2 includes a red host material RH and a red guest material RD, where the red host material RH includes a P-type material and an N-type material; the doping concentration of the P-type material is greater than or equal to that of the N-type material. For example, the mass ratio of the P-type material to the N-type material is between 1:1 and 9:1. In the present disclosure, on the basis of increasing the thickness of the second emitting layer EML2, the doping ratio of the P-type material and the N-type material in the second emitting layer EML2 is further adjusted, so as to adjust the holes captured by the second electron blocking layer EBL2 (referring to the second electron blocking layer EBL2 doped with an exciton trapping agent), and further ensure the balance of carriers in the second emitting layer EML2.

[0115] Optionally, the materials of the first emitting layer EML1 and the second emitting layer EML2 are different. The mobility of the second emitting layer EML2 is set to be greater than that of the first emitting layer EML1, so as to improve the device voltage increase caused by the increase in the thickness of the second emitting layer EML2.

[0116] In some embodiments, as Figure 3 shown, the charge generation and separation unit 4 includes an N-type charge generation layer N-CGL and a P-type charge generation layer P-CGL arranged in sequence along the direction from the anode 1 to the cathode 2. The first light emitting unit 31 further includes a hole injection layer HIL provided on the anode 1 near the first electron blocking layer EBL1, a first hole transport layer HTL1 provided on one side of the hole injection layer HIL near the first electron blocking layer EBL1, a first hole blocking layer HBL1 provided on one side of the first emitting layer EML1 near the N-type charge generation layer N-CGL, and a first electron transport layer ETL1 provided on one side of the first hole blocking layer HBL1 near the N-type charge generation layer N-CGL; the second light emitting unit 32 further includes an electron injection layer EIL, a second electron transport layer ETL2 and a second hole blocking layer HBL2 arranged on the cathode 2 in sequence along the direction from the cathode 2 to the second emitting layer EML2, and a second hole transport layer HTL2 provided between the second electron blocking layer EBL2 and the P-type charge generation layer P-CGL.

[0117] The above functional layers for assisting carrier transport are described in detail from aspects of physical properties such as energy level, mobility and material, and the physical property matching of different functional layers is reasonably adjusted to ensure efficient generation, injection and transport of carriers, thereby improving the overall performance of the tandem OLED.

[0118] In terms of energy levels: The absolute value of the difference between the LUMO energy level of the N-type charge generation layer N-CGL and the LUMO energy level of the first hole blocking layer HBL1 is less than or equal to 0.5 eV, that is, |LUMO(N-CGL) - LUMO(HBL1)| ≤ 0.5 eV. In this way, the energy level transmission barrier can be reduced, enabling electrons to be effectively injected into the adjacent first emitting layer EML1. The absolute value of the difference between the HOMO energy level of the P-type charge generation layer P-CGL and the HOMO energy level of the second hole transport layer HTL2 is less than or equal to 0.3 eV, that is, |HOMO(P-CGL) - HOMO(HTL2)| ≤ 0.3 eV. In this way, the energy level transmission barrier can be reduced, enabling holes to be effectively injected into the adjacent second emitting layer EML2.

[0119] The absolute value of the difference between the HOMO energy level of the first hole transport layer HTL1 and the HOMO energy level of the first electron blocking layer EBL1 ranges from 0.1 eV to 0.4 eV, that is, 0.1 eV ≤ |HOMO(HTL1) - HOMO(EBL1)| ≤ 0.4 eV; the absolute value of the difference between the HOMO energy level of the second hole transport layer HTL2 and the HOMO energy level of the second electron blocking layer EBL2 ranges from 0.1 eV to 0.4 eV, that is, 0.1 eV ≤ |HOMO(HTL2) - HOMO(EBL2)| ≤ 0.4 eV. In this way, the problem of slow hole transport caused by the energy level barrier can be eliminated, and the hole transport can be accelerated to a certain extent.

[0120] The following is an explanation of a single light-emitting device. It should be especially emphasized that the organic functional layers without the "first" and "second" designations generally refer to the first organic functional layer and the second organic functional layer. When comparing parameters (such as energy levels), the film layers in the same light-emitting unit are compared, that is, the first is compared with the first, and the second is compared with the second. For example, the hole transport layer HTL generally refers to the first hole transport layer HTL1 and the second hole transport layer HTL2; the electron blocking layer EBL generally refers to the first electron blocking layer EBL1 and the second electron blocking layer EBL2; the hole blocking layer HBL generally refers to the first hole blocking layer HBL1 and the second hole blocking layer HBL2; the electron transport layer ETL generally refers to the first electron transport layer ETL1 and the second electron transport layer ETL2; the emitting layer EML generally refers to the first emitting layer EML1 and the second emitting layer EML2.

[0121] For the red light-emitting device R or the green light-emitting device G, the material of the light-emitting layer EML includes a light-emitting host material and a light-emitting guest material. Among them, the light-emitting host material includes a P-type material (P-RH or P-GH) and an N-type material (N-RH or N-GH). Taking the exciplex of the light-emitting host material as an example, the absolute value of the difference between the HOMO energy level of the P-type material and the HOMO energy level of the material of the electron blocking layer EBL is less than or equal to 0.3 eV, that is, |HOMO(P-RH / P-GH) - HOMO(EBL)| ≤ 0.3 eV. By setting a smaller HOMO band gap, it is beneficial to the transport of holes. The difference between the LUMO energy level of the material of the electron blocking layer EBL and the LUMO energy level of the P-type material is greater than or equal to 0.3 eV, that is, LUMO(EBL) - LUMO(P-RH / P-GH) ≥ 0.3 eV, which is beneficial to the blocking of electrons. The absolute value of the difference between the LUMO energy level of the material of the hole blocking layer HBL and the LUMO energy level of the N-type material is less than or equal to 0.3 eV, that is, |LUMO(HBL) - LUMO(N-RH / N-GH)| ≤ 0.3 eV. By setting a smaller LUMO band gap, it is beneficial to the transport of electrons. The difference between the HOMO energy level of the material of the hole blocking layer HBL and the HOMO energy level of the N-type material is greater than or equal to 0.3 eV, that is, HOMO(HBL) - HOMO(N-RH / N-GH) ≥ 0.3 eV, which is beneficial to the blocking of holes.

[0122] For the blue light-emitting device B, the material of the light-emitting layer EML includes a light-emitting host material and a light-emitting guest material, and the light-emitting host material is a single host or an exciplex. Taking the blue single host of the light-emitting host material as an example, the absolute value of the difference between the HOMO energy level of the blue single host (BH) and the HOMO energy level of the material of the electron blocking layer EBL is less than or equal to 0.3 eV, that is, |HOMO(BH) - HOMO(EBL)| ≤ 0.3 eV. By setting a smaller HOMO band gap, it is beneficial to the transport of holes. The absolute value of the difference between the LUMO energy level of the material of the hole blocking layer HBL and the LUMO energy level of the blue single host is less than or equal to 0.3 eV, that is, |LUMO(HBL) - LUMO(BH)| ≤ 0.3 eV. By setting a smaller LUMO band gap, it is beneficial to the transport of electrons.

[0123] Optionally, for the blue light-emitting device B, the triplet energy level T1 of the first hole blocking layer HBL1 is greater than the triplet energy level T1 of the blue host material BH of the first light-emitting material; the triplet energy level T1 of the first electron blocking layer EBL1 is greater than the triplet energy level T1 of the blue host material BH of the first light-emitting material. In this way, when the blue light-emitting layer EML emits fluorescence, satisfying the above conditions can make full use of the TTA mechanism to improve the utilization rate of excitons, and thus improve the efficiency of the blue OLED device.

[0124] The energy level relationship of the red light-emitting device R and the green light-emitting device G Figure 5 is a schematic diagram showing the comparison of the energy level relationships of the red light-emitting device R and the green light-emitting device G provided by the embodiments of the present disclosure, as Figure 5 shown, in which the HOMO energy level of the P-type material P-RH of the red light-emitting device R is shallower than the HOMO energy level of the P-type material P-GH of the green light-emitting device G, and the LUMO energy level of the N-type material N-RH of the red light-emitting device R is deeper than the LUMO energy level of the N-type material N-GH of the green light-emitting device G.

[0125] When the light-emitting device design of the embodiments of the present disclosure satisfies the above conditions, holes and electrons can recombine and emit light well in the light-emitting layer EML, and at the same time, the hole and electron transport rates are adjusted, which is beneficial to the balance of carriers in the exciton recombination region, making the exciton recombination region far from the electron blocking layer EBL side.

[0126] In terms of mobility: taking the thickness of the second light-emitting layer EML2 being greater than the thickness of the first light-emitting layer EML1 as an example, the materials of the first light-emitting layer EML1 and the second light-emitting layer EML2 are different, and the mobility of the light-emitting host material of the second light-emitting layer EML2 is greater than the mobility of the light-emitting host material of the first light-emitting layer EML1, thereby improving the device voltage increase caused by the increase in the thickness of the second light-emitting layer EML2.

[0127] The material of the first hole transport layer HTL1 is different from the material of the second hole transport layer HTL2; the mobility of the first hole transport layer HTL1 is greater than the mobility of the second hole transport layer HTL2, which is beneficial to the transport of holes, and further reduces the operating voltage of the device.

[0128] The ratio of the mobility of holes to the mobility of electrons in the material of the light-emitting layer EML is between 0.01 and 100.

[0129] Material aspect: For the red light-emitting device R, the materials of the emitting layer EML include a red host material RH (light-emitting host material) and a red guest material RD (light-emitting guest material). Among them, the red host material RH can be an exciplex. By using the exciplex, the balance of carriers in the emitting layer EML can be regulated, thereby effectively regulating the exciton recombination region to be located at the center of the emitting layer EML, which is beneficial to increasing the exciton utilization rate and further improving the overall luminous efficiency of the tandem red OLED. Exemplarily, the red host material RH is a hole-biased material. In this way, while ensuring red light emission, holes can be transferred to the emitting layer EML of the green light-emitting device G, facilitating the radiation of light by the green light-emitting device G. The red guest material RD can be a phosphorescent dopant.

[0130] For the green light-emitting device G, the materials of the emitting layer EML include a green host material GH (light-emitting host material) and a green guest material GD (light-emitting guest material). The green host material GH can be an exciplex. By using the exciplex, the balance of carriers in the emitting layer EML can be regulated, thereby effectively regulating the exciton recombination region to be located at the center of the emitting layer EML, which is beneficial to increasing the exciton utilization rate and further improving the overall luminous efficiency of the tandem green OLED. The green guest material GD can be a phosphorescent dopant.

[0131] For the blue light-emitting device B, the materials of the emitting layer EML include a blue host material BH (light-emitting host material) and a blue guest material BD (light-emitting guest material). The blue host material BH is a single host or an exciplex. Exemplarily, when the blue host material BH is a single host, an anthracene-containing material can be selected; the blue guest material BD can be a fluorescent material. Another exemplarily, when the blue host material BH is an exciplex; the blue guest material BD can be a phosphorescent dopant.

[0132] The P-type charge generation layer P-CGL is used to generate holes and inject them into the first light-emitting unit 31. The materials of the P-type charge generation layer P-CGL include a P-type host material and a first dopant. Optionally, the P-type host material can be a hole-type material, such as NPB or TPD, etc. Optionally, the first dopant can be a material represented by structural formula (II) or structural formula (III).

[0133] Structural formula (II):

[0134] Among them, A1 - A6 each independently represent a substituted or unsubstituted halogen, a substituted or unsubstituted cyano group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group; when A1 - A6 each independently represent an aryl group as a substituent, the aryl group can be substituted by an electron-withdrawing group; A represents a three-membered ring, a four-membered ring, a five-membered ring, or a six-membered ring.

[0135] Exemplarily, the structure of the first dopant shown in the general structural formula (II) includes any one of the following (2-1 to 2-12).

[0136]

[0137] General structural formula (III):

[0138] Wherein, X1 and X2 each independently represent one of C, N, and Si; Y1 and Y2 each independently represent one of O, N, and S; Ar1 - Ar4 each independently represent a substituted or unsubstituted halogen, a substituted or unsubstituted cyano group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted adamantane group, a substituted or unsubstituted heteroaryl group; R1 and R2 each independently represent deuterium, a halogen group, a cyano group, a substituted or unsubstituted heteroaryl group with 3 to 20 carbon atoms, a substituted or unsubstituted aryl group with 6 to 20 carbon atoms, a substituted or unsubstituted alkyl group with 1 to 5 carbon atoms, a substituted or unsubstituted haloalkyl group with 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group with 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group with 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group with 1 to 10 carbon atoms, a substituted or unsubstituted alkylthio group with 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group with 6 to 18 carbon atoms, an arylthio group with 6 to 18 carbon atoms, a phosphoxy group with 6 to 24 carbon atoms, a substituted or unsubstituted alkylsulfonyl group with 6 to 18 carbon atoms; a and b each independently represent an integer from 1 to 5.

[0139] Wherein, the compound in the general structural formula (III) contains a large number of electron-withdrawing groups, such as NC, CN, and CF3 in Example 3-1. This compound and the P-type host material can form a structure conducive to hole transport through the co-evaporation process, thereby ensuring the effective generation and efficient transport of holes.

[0140] Exemplarily, the structure of the first dopant shown in the general structural formula (III) includes any one of the following (3-1 to 3-15).

[0141]

[0142]

[0143] The N-type charge generation layer N-CGL is used to generate electrons and inject them into the second light-emitting unit 32. The N-type charge generation layer N-CGL includes an N-type host material and a second dopant. Optionally, the N-type host material may be a material represented by structural general formula (IV). The second dopant may be selected from alkali metals and their compounds such as lithium (Li), sodium (Na), potassium (K), or cesium (Cs), or alkaline earth metals and their compounds such as magnesium (Mg), strontium (Sr), barium (Ba), or radium (Ra), or alkaline earth metals and their oxides, or transition metals and their compounds, etc.

[0144] Structural general formula (IV):

[0145] Wherein, X1-X4 each independently represents N or C(R1), and X1-X4 each independently contains at least 2 Ns; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-C60 alkynyl, substituted or unsubstituted C1-C60 alkoxy, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C1-C10 heterocycloalkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocycloalkenyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C6-C60 arylthio, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group; Ar1, Ar2, Ar3, Ar4 are the same or different, and each independently represents one selected from the following: hydrogen, deuterium, tritium, halogen, cyano, nitro, C6-C60 aryl, C2-C60 heterocyclic group containing at least one heteroatom from O, N, S, Si, and P, C3-C60 aliphatic ring, fused ring group of C6-C60 aromatic ring, C1-C50 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C30 alkoxy, C6-C30 aryloxy, C3-C60 alkylsilyl, C18-C60 arylsilyl, C8-C60 alkylarylsilyl.

[0146] Wherein, the heterocyclic compound represented by structural general formula (IV) has a deep LUMO energy level, reducing the potential barrier at the junction interface between the N-type charge generation layer N-CGL and the P-type charge generation layer P-CGL, thereby suppressing the deterioration at the interface caused by the accumulation of carriers due to the energy level potential barrier at the interface.

[0147] In addition, the heterocyclic compound represented by Structural General Formula (IV) also has an N atom with sp2 hybridization, endowing this type of compound with excellent electron transport ability. This enables the electron flow generated by the PN (p-i-n) junction formed in the N-type charge generation layer N-CGL and the P-type charge generation layer P-CGL to be rapidly transported through the N-type charge generation layer N-CGL to the first light-emitting layer EML1 for radiative emission. Meanwhile, the lone pair of electrons of the N atom with sp2 hybridization can form a complex with the active metal compound in the N-type charge generation layer N-CGL. This can not only inhibit the crystallization of the material represented by Structural General Formula (IV), but also increase the electron injection ability of the N-type charge generation layer N-CGL, and can control the crystallization occurring at the interface between the first electron transport layer ETL1 and the N-type charge generation layer N-CGL, improving the uniformity of the interface morphology. In this way, the charge flow in the OLED device can be improved, thereby reducing the driving voltage.

[0148] Exemplarily, the structure of the first dopant represented by Structural General Formula (IV) includes any one of the following (4-1 to 4-18).

[0149]

[0150]

[0151] In some embodiments, as Figure 3 shown, the materials of each functional layer can also adopt the following examples.

[0152] Optionally, the anode 1 can select a high work function electrode material, such as transparent oxides ITO, IZO; or a composite electrode formed by ITO / Ag / ITO, Ag / IZO, CNT / ITO, CNT / IZO, GO / ITO, GO / IZO, etc.

[0153] Optionally, the hole injection layer HIL is mainly used to reduce the hole injection barrier and improve the hole injection efficiency. The material of the hole injection layer HIL can be an inorganic oxide, such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide, manganese oxide, etc.

[0154] Alternatively, the material of the hole injection layer HIL can also be a dopant with a strong electron-withdrawing system, such as F4TCNQ, HATCN, PPDN, etc. or a triaxial xanthene compound. Among them, the structural formula of HATCN is The structural formula of F4TCNQ is The structural formula of PPDN is The structural formula of the triaxial xanthene compound is

[0155] Alternatively, the material of the hole injection layer HIL can also be P-doped in the hole transport material. The thickness of the hole injection layer HIL is between 5 and 20 nm, and the hole injection layer HIL can be formed by co-evaporating the hole transport material and P-doping.

[0156] Optionally, the hole transport layer HTL is mainly used to transport holes. The material of the hole transport layer HTL needs to have good hole transport characteristics, such as arylamine or carbazole materials, such as NPB, TCTA, TAPC, TPD, BAFLP, DFLDPBi, etc. Among them, the structural formula of NPB is The structural formula of TCTA is The structural formula of TAPC is

[0157] Optionally, the first electron blocking layer EBL1 is mainly used to confine excitons in the emitting layer EML, prevent the leakage of excitons to both sides of the emitting layer EML and cause efficiency loss, and also has good hole transport characteristics. It can be arylamine or carbazole materials, such as CBP or PCzPA, etc. The material of the second electron blocking layer EBL2 is doped with an exciton trapping agent on the basis of the material of the first electron blocking layer EBL1. The specific structure of the exciton trapping agent can be seen in the general structural formula (I). The exciton trapping agent is mainly used to trap excess carriers in the second electron blocking layer EBL2, prevent too many holes from entering the emitting layer EML and cause a significant attenuation of the device efficiency. Therefore, it can be set as a material with a shallower HOMO energy level than the HOMO energy level of the second electron blocking layer EBL2.

[0158] The material of the first electron blocking layer EBL1 of the red light-emitting device R is The material of the first electron blocking layer EBL1 of the green light-emitting device G is The material of the first electron blocking layer EBL1 of the blue light-emitting device B is

[0159] Optionally, the red host material RH can be selected from DCM series materials, such as DCM, DCJTB, DCJTI, etc. The red host material RH selects DCzDBT, and its structural formula is Or, the red host material RH selects a P-type material Or, the red host material RH selects an N-type material The red guest material RD can be a metal complex, such as Ir(piq)2(acac), PtOEP, Ir(btp)2(acac), etc. Among them, the structural formula of (Ir(piq)2(acac) is

[0160] Optionally, the green host material GH can be selected from, for example, coumarin dyes, quinacridone derivatives, polycyclic aromatic hydrocarbons, diaminoanthracene derivatives, carbazole derivatives such as DMQA, BA-NPB, Alq3, etc. The green host material GH selects CBP, and its structural formula is Or the green host material GH selects a P-type material Or the green host material GH selects an N-type material The green guest material GD can be a metal complex, etc., such as Ir(ppy)3, Ir(ppy)2(acac), etc. Among them, the structural formula of Ir(ppy)3 is

[0161] Optionally, the blue host material BH can be selected from anthracene derivatives such as ADN, MADN, etc. Among them, the structural formula of AND is The blue guest material BD can be a pyrene derivative, a fluorene derivative, a perylene derivative, a styrylamine derivative, a metal complex, etc., such as TBPe, BDAVBi, DPAVBi, FIrpic, etc. Among them, the structural formula of DPAVBi is Or, the blue guest material BD selects

[0162] Optionally, the materials of the hole blocking layer HBL and the electron transport layer ETL can be selected from aromatic heterocyclic compounds, such as imidazole derivatives such as benzimidazole derivatives, imidazopyridine derivatives, benzimidazophenanthridine derivatives, etc.; pyrimidine derivatives, triazine derivatives and other pyrazine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives and other compounds containing a nitrogen-containing six-membered ring structure (also including compounds having a phosphine oxide-based substituent on the heterocycle, for example: OXD-7, TAZ, p-EtTAZ, BPhen, BCP, etc.).

[0163] Exemplarily, the material of the hole blocking layer HBL is The material of the electron transport layer ETL can be selected from BPhen, TPBi, or etc. Among them, the structural formula of BPhen is The structural formula of TPBi is

[0164] Optionally, the P-type host material of the P-type charge generation layer P-CGL can be selected from hole-type materials, such as NPB or TPD, etc. Among them, the structural formula of NPB is The first dopant of the P-type charge generation layer P-CGL can be HATCN, F4TCNQ, PPDN or a triaxene compound, etc.; among them, the structural formula of HATCN The structural formula of PPDN is The structural formula of the triaxene compound is

[0165] Optionally, the N-type host material of the N-type charge generation layer N-CGL can be selected from electron-type materials containing phenanthroline or phosphine oxide, such as The second dopant can be selected from alkali metals such as lithium (Li), ytterbium (Yb), sodium (Na), potassium (K), or cesium (Cs) and their compounds, or alkaline earth metals such as magnesium (Mg), strontium (Sr), barium (Ba), or radium (Ra) and their compounds, or alkaline earth metals and their oxides, or transition metals and their compounds, etc.

[0166] Optionally, the material of the electron injection layer EIL can be selected from alkali metals or metals, such as LiF, Yb, Mg, Ca, and their respective compounds, etc.

[0167] In some embodiments, as Figure 3 shown, the following examples can also be adopted for the thickness ranges of the respective organic functional layers.

[0168] Optionally, anode 1 (150 - 300 nm), hole injection layer HIL (5 - 30 nm), first hole transport layer HTL1 (10 - 40 nm), first electron blocking layer REBL1 of red light-emitting device R (20 - 60 nm), first electron blocking layer GEB L1 of green light-emitting device G (5 - 30 nm), first electron blocking layer BEBL1 of blue light-emitting device B (5 - 15 nm), first light-emitting layer REML1 of red light-emitting device R (20 - 60 nm), first light-emitting layer GEML1 of green light-emitting device G (20 - 50 nm), first light-emitting layer BEML1 of blue light-emitting device B (10 - 40 nm), first hole blocking layer HBL1 (5 - 15 nm), first electron transport layer ETL1 (10 - 40 nm), N-type charge generation layer N-CGL (15 - 25 nm), P-type charge generation layer P-CGL (5 - 15 nm), second hole transport layer HTL2 (5 - 70 nm), second electron blocking layer REBL2 of red light-emitting device R (5 - 45 nm), second electron blocking layer GEB L2 of green light-emitting device G (10 - 25 nm), second electron blocking layer BEBL2 of blue light-emitting device B (5 - 15 nm), second light-emitting layer REML2 of red light-emitting device R (30 - 80 nm), second light-emitting layer GEML2 of green light-emitting device G (20 - 50 nm), second light-emitting layer BEML2 of blue light-emitting device B (10 - 40 nm), second hole blocking layer HBL2 (5 - 15 nm), second electron transport layer ETL2 (20 - 100 nm), electron injection layer EIL (1 - 15 nm), cathode 2 (10 - 20 nm).

[0169] The following uses an example to illustrate the red light-emitting device R, green light-emitting device G, and blue light-emitting device B employed in the embodiments and comparative examples of the present disclosure.

[0170] The materials used for each light-emitting device are specifically as follows: The material of the anode 1 is indium tin oxide ITO; the material of the hole injection layer HIL is The materials of the first hole transport layer HTL1 and the second hole transport layer HTL2 are the same, both being The material of the first electron blocking layer EBL1 of the red light-emitting device R is selected as The material of the second electron blocking layer EBL2 of the red light-emitting device R is a material doped with an exciton dopant based on the material of the first electron blocking layer EBL1 of the red light-emitting device R. The material of the first electron blocking layer EBL1 of the green light-emitting device G is The material of the second electron blocking layer EBL2 of the green light-emitting device G is a material doped with an exciton dopant based on the material of the first electron blocking layer EBL1 of the green light-emitting device G. The material of the first electron blocking layer EBL1 of the blue light-emitting device B is The material of the second electron blocking layer EBL2 of the blue light-emitting device B is a material doped with an exciton dopant based on the material of the first electron blocking layer EBL1 of the blue light-emitting device B. The red host material RH is an exciplex, where the exciplex includes a P-type material and an N-type material The red guest material RD is The green host material GH is an exciplex, where the exciplex includes a P-type material and an N-type material The green guest material GD is The blue host material BH is The blue guest material BD is The materials of the first hole blocking layer HBL1 and the second hole blocking layer HBL2 are the same, both being The materials of the first electron transport layer ETL1 and the second electron transport layer ETL2 are the same, both being The N-type host material of the N-type charge generation layer N-CGL is The second doping material is metal Yb. The P-type host material of the P-type charge generation layer P-CGL is The first doping material is The material of the electron injection layer EIL is metal Yb. The material of the cathode 2 is a MgAg material (doping ratio 1:9). It should be noted that unless otherwise specified in the present disclosure, the materials used in the following "comparative examples" are the materials given in this paragraph as examples.

[0171] Based on the above-mentioned organic light-emitting device with the given materials and thickness, by adjusting some parameters, the device performance is improved. The comparison table between the comparative examples and the embodiments of the present disclosure is as follows.

[0172] Taking the above-mentioned relational expression (1) as an example, the ratio L1 / L2 between the sum of the thickness of the first light-emitting layer EML1 and the thickness of the first electron blocking layer EBL1 (the first thickness) L1 and the sum of the thickness of the second light-emitting layer EML2 and the thickness of the second electron blocking layer EBL2 (the second thickness) L2 determines the performance (including voltage, efficiency, and lifespan) of each light-emitting device through different simulation results.

[0173] R L1(R) / L2(R) Voltage Efficiency Lifetime Comparative Example 1 0.5 101％ 88％ 90％ Comparative Example 2 1.3 102％ 95％ 83％ Example 3 1 100％ 100％ 100％

[0174] G L1(G) / L2(G) Voltage Efficiency Lifetime Comparative Example 1 0.7 103％ 83％ 94％ Comparative Example 2 1.25 102％ 96％ 86％ Example 3 1 100％ 100％ 100％

[0175] B L1(B) / L2(B) Voltage Efficiency Lifetime Comparative Example 1 0.6 100％ 85％ 79％ Comparative Example 2 1.4 99％ 89％ 87％ Example 3 1 100％ 100％ 100％

[0176] From the comparison results between the above-mentioned comparative examples and embodiments, it can be seen that the embodiments of the present disclosure adjust L1 / L2 and optimize the light-emitting position. On the premise of ensuring that the light-emitting layer EML is near the antinode point (microcavity enhancement region), the superposition effect of the upper and lower light-emitting layers EML is further improved.

[0177] Taking the above-mentioned relational expression (3) as an example, the ratio L3 / L of the distance L3 between the third surface and the first surface of the first light-emitting layer EML1 close to the anode 1 to the microcavity length L determines the performance (including voltage, efficiency, and lifespan) of each light-emitting device through different simulation results.

[0178] R L3(R) / L(R) Voltage Efficiency Lifetime Comparative Example 1 0.1 103％ 88％ 92％ Comparative Example 2 0.5 102％ 90％ 87％ Example 3 0.24 100％ 100％ 100％

[0179] G L3(G) / L(G) Voltage Efficiency Lifetime Comparative Example 1 0.08 103％ 94％ 88％ Comparative Example 2 0.4 102％ 89％ 86％ Example 3 0.18 100％ 100％ 100％

[0180] B L3(B) / L(B) Voltage Efficiency Lifetime Comparative Example 1 0.05 102％ 91％ 91％ Comparative Example 2 0.35 103％ 86％ 93％ Example 3 0.21 100％ 100％ 100％

[0181] From the comparison results between the above-mentioned comparative examples and embodiments, it can be seen that the embodiments of the present disclosure optimize L3 / L and adjust the first light-emitting layer EML1 of the tandem OLED device to near the antinode point (microcavity enhancement region) of the resonant microcavity, improving the light extraction efficiency of the tandem OLED device.

[0182] Taking the above-mentioned relational expression (4) as an example, the ratio L4 / L of the distance L4 between the fourth surface and the first surface of the second light-emitting layer EML2 close to the anode 1 to the microcavity length L determines the performance (including voltage, efficiency, and lifespan) of each light-emitting device through different simulation results.

[0183] R L4(R) / L(R) Voltage Efficiency Lifetime Comparative Example 1 0.4 103％ 86％ 97％ Comparative Example 2 0.8 101％ 82％ 96％ Example 3 0.6 100％ 100％ 100％

[0184] G L4(G) / L(G) Voltage Efficiency Lifetime Comparative Example 1 0.5 102％ 90％ 92％ Comparative Example 2 0.85 100％ 82％ 91％ Example 3 0.66 100％ 100％ 100％

[0185] B L4(B) / L(B) Voltage Efficiency Lifetime Comparative Example 1 0.5 101％ 90％ 93％ Comparative Example 2 0.9 103％ 95％ 91％ Example 3 0.71 100％ 100％ 100％

[0186] From the comparison results of the above comparative examples and embodiments, it can be seen that in the embodiments of the present disclosure, L4 / L is optimized, and the second emission layer EML2 of the tandem OLED device is adjusted to near the antinode point (microcavity enhancement region) of the resonant microcavity, thereby improving the light extraction efficiency of the tandem OLED device.

[0187] Taking the above relationship (V) as an example, the ratio L5 / L of the third thickness L5 of the charge generation and separation unit 4 to the microcavity length L determines the performance (including voltage, efficiency, and lifetime) of each light-emitting device through different simulation results.

[0188] R L5(R) / L(R) Voltage Efficiency Lifetime Comparative Example 1 0.05 103％ 96％ 82％ Comparative Example 2 0.15 98％ 89％ 95％ Example 3 0.09 100％ 100％ 100％

[0189] G L5(G) / L(G) Voltage Efficiency Lifetime Comparative Example 1 0.05 102％ 92％ 85％ Comparative Example 2 0.2 100％ 89％ 94％ Example 3 0.12 100％ 100％ 100％

[0190] B L5(B) / L(B) Voltage Efficiency Lifetime Comparative Example 1 0.05 104％ 93％ 89％ Comparative Example 2 0.2 103％ 95％ 91％ Example 3 0.15 100％ 100％ 100％

[0191] From the comparison results of the above comparative examples and embodiments, it can be seen that in the embodiments of the present disclosure, optimizing L5 / L can improve the crosstalk phenomenon between different pixels, reduce the voltage of the device, and ensure that the tandem OLED has relatively low power consumption.

[0192] For the red light-emitting device R, the thicknesses of the first emission layer EML1 and the second emission layer EML2 are further improved.

[0193] R Thickness magnitude relationship Voltage Efficiency Lifetime Comparative Example 1 EML1 > EML2 99％ 96％ 82％ Example 2 EML1 < EML2 100％ 100％ 100％

[0194] Verified by simulation experiments, the second emission layer EML2 mainly has a significant impact on the lifetime of the red OLED device. Increasing the thickness of the second emission layer EML2 is beneficial to broadening the exciton recombination region and moving it towards the center of the second emission layer EML2, thereby improving the device lifetime.

[0195] For the red light-emitting device R, the thicknesses of the first electron blocking layer EBL1 and the second electron blocking layer EBL2 are further improved.

[0196] R Doped exciton trapping agent Thickness magnitude relationship Voltage Efficiency Lifetime Comparative Example 1 Undoped EBL1 > EBL2 102％ 82％ 85％ Example Doped EBL1 < EBL2 100％ 100％ 100％

[0197] Verified by simulation experiments, the second electron blocking layer EBL2 is doped with exciton trappers, which can ensure good trapping effect and can well trap the holes injected into the second electron blocking layer EBL2. Further, the thickness of the second electron blocking layer EBL2 is greater than that of the first electron blocking layer EBL1, which can cause a large number of holes in the second electron blocking layer EBL2 to be trapped, resulting in a significant reduction in exciton recombination in the second electron blocking layer EBL2, thereby reducing the exciton utilization rate and further significantly reducing the lifetime and efficiency of the device.

[0198] For the red light-emitting device R, further improve the material of the electron blocking layer EBL, that is, dope exciton trappers.

[0199] R Trapping agent doping concentration Voltage Efficiency Lifetime Comparative Example 1 Undoped 98％ 82％ 89％ Example 1 0.5％ 100％ 100％ 100％ Example 2 1％ 103％ 90％ 95％ Example 3 1.5％ 105％ 96％ 87％

[0200] Verified by simulation experiments, by optimizing the doping concentration of exciton trappers in the material of the electron blocking layer EBL, the lifetime and efficiency of the light-emitting device can be balanced.

[0201] Exemplarily, in combination with the above material examples, the embodiments that the red light-emitting device R can select and their device effects are as shown in Table 1 below.

[0202] Table 1

[0203]

[0204]

[0205] Exemplarily, in combination with the above material examples, the embodiments that the green light-emitting device G can select and their device effects are as shown in Table 2 below.

[0206] Table 2

[0207]

[0208]

[0209] Exemplarily, in combination with the above material examples, the embodiments that the blue light-emitting device B can select and their device effects are as shown in Table 3 below.

[0210] Table 3

[0211]

[0212]

[0213] The above is all the descriptions of the light-emitting device provided by the embodiments of the present disclosure.

[0214] In addition, the embodiments of the present disclosure further provide a display panel, which includes the light-emitting device of any of the above embodiments and their combinations.

[0215] Specifically, Figure 6 A schematic diagram of multiple light-emitting devices in a display panel provided by an embodiment of the present disclosure, such as Figure 6 As shown, the display panel includes a substrate, a plurality of light-emitting devices arranged on the substrate; the light-emitting devices include an anode 1, a cathode 2, a plurality of light-emitting units arranged between the anode 1 and the cathode 2, and a charge generation separation unit 4 arranged between adjacent light-emitting units. The plurality of light-emitting units include at least a first light-emitting unit 31 and a second light-emitting unit 32, and the first light-emitting unit 31 is closer to the anode 1 than the second light-emitting unit 32. The present disclosure takes two light-emitting units as an example, and the charge generation separation unit 4 is located between the first light-emitting unit 31 and the second light-emitting unit 32. The plurality of light-emitting devices include, for example, a red light-emitting device R, a green light-emitting device G, and a blue light-emitting device B.

[0216] In some embodiments, the display panel also includes a partition structure arranged between two adjacent light-emitting devices; wherein the two light-emitting devices emit light of different colors, and the charge generation separation units 4 of the two light-emitting devices are separated at the position of each partition structure, thereby blocking the lateral flow of charges and improving color crosstalk between different light-emitting devices.

[0217] Optionally, the charge generation and separation unit 4 in each light-emitting device is an integrated structure.

[0218] In one possible implementation, Figure 7 A schematic diagram of a partition structure in Example 1 of a display panel provided in an embodiment of the present disclosure, as shown in FIG. Figure 7 As shown, the display panel further includes a pixel defining layer PDL and a support layer 02 disposed on the side of the pixel defining layer PDL away from the base substrate 01; the pixel defining layer PDL includes a pixel opening V corresponding to each light-emitting device and a retaining wall structure forming the pixel opening V. The support layer 02 includes a support portion 021 located on the retaining wall structure, and the support portion 021 is reused as a partition structure. Specifically, the longitudinal section of the support portion 021 along its thickness direction is an inverted trapezoid, and its lower surface is concavely designed, which can be used to isolate the charge generation separation unit 4 located on its upper layer, thereby improving the color crosstalk between different light-emitting devices.

[0219] Exemplarily, the support portion 021 includes an upper surface and a lower surface arranged opposite to each other along its thickness direction, and a side surface connecting the upper surface and the lower surface. The dihedral angle α formed between the side surface and the lower surface is in the range of 30° to 80°, thereby avoiding an inclination angle that is too large or too large to serve as a partition, and also avoiding discontinuity of the cathode 2 caused by transitional partition.

[0220] Exemplarily, the thickness H1 of the support portion 021 is between 0.8 and 2 μm, to avoid that a too high height fails to play a shielding role and that a too low height fails to play a partitioning role.

[0221] In another possible implementation manner, Figure 8 is a schematic diagram of the partitioning structure in Example 2 of the display panel provided by the embodiments of the present disclosure. As Figure 8 shown, the display panel further includes a pixel definition layer PDL and a support layer 02 disposed on a side of the pixel definition layer PDL away from the substrate 01; the pixel definition layer PDL includes pixel openings V corresponding to respective light-emitting devices one by one, transition openings V0 located between adjacent two light-emitting devices, and a barrier structure forming the pixel openings V and the transition openings V0. The support layer 02 includes a support portion 021 located on the barrier structure. The difference from the above Figure 7 implementation manner is that the support portion 021 is not a partitioning structure. The longitudinal section of the support portion 021 along its thickness direction is trapezoidal, and the dihedral angle α' formed between the side surface and the lower surface is greater than 90°.

[0222] The display panel further includes a passivation layer PVX disposed on a side of the pixel definition layer PDL close to the substrate 01, a planarization layer PLN disposed on a side of the passivation layer PVX close to the substrate 01, and a driving layer 0341 disposed on a side of the planarization layer PLN close to the substrate 01. The driving layer includes a pixel driving circuit (not shown in the figure) for driving respective light-emitting devices. The planarization layer PLN is used to planarize the lower pixel driving circuit, ensuring that the upper light-emitting devices are fabricated on a relatively flat surface.

[0223] The passivation layer PVX includes first opening portions 41 corresponding to the transition openings V0 one by one. The planarization layer PLN includes second opening portions 42 corresponding to the first opening portions 41 one by one. The opening size of the first opening portion 41 is smaller than the opening size of the second opening portion 42, and the difference therebetween is between 0.1 and 1 μm. Thus, a step difference is formed between the first opening portion 41 and the second opening portion 42, thereby forming a partitioning structure, which can partition the charge generation and separation unit 4, thus improving color crosstalk between different light-emitting devices.

[0224] Exemplarily, the thickness of the passivation layer PVX is between 0.1 and 0.5 μm. The first opening portion 41 penetrates through the entire thickness of the passivation layer PVX. The depth of the second opening portion 42 is between 0.1 and 1.2 μm. The second opening portion 42 penetrates through a partial thickness of the planarization layer PLN. The angle β between the opening sidewall of the second opening portion 42 and the horizontal surface of the passivation layer PVX close to the planarization layer PLN is between 60° and 90°.

[0225] In another possible implementation manner, Figure 9Schematic diagram of the partition structure in Example 3 of the display panel provided by the embodiments of the present disclosure, as Figure 9 shown, the display panel further includes a pixel definition layer PDL, and the pixel definition layer PDL includes pixel openings V corresponding to each light-emitting device one by one, and a barrier structure for forming the pixel openings V.

[0226] The pixel definition layer PDL includes a multi-layer structure, such as two layers or three layers. In the present disclosure, the case where the pixel definition layer PDL is a three-layer structure is taken as an example for description. Figure 10 For Figure 9 the enlarged view of the partition structure in Figure 10 shown, the barrier structure of the pixel definition layer PDL includes a first sub-layer 51, a second sub-layer 52, and a third sub-layer 53 sequentially arranged in a direction away from the substrate 01; the first sub-layer 51 is used to define one side of the pixel opening V protruding from the side of the second sub-layer 52 for defining the pixel opening V, and the third sub-layer 53 is used to define one side of the pixel opening V protruding from the side of the second sub-layer 52 for defining the pixel opening V. In this way, a step difference is formed between the third sub-layer 53 and the second sub-layer 52, thereby forming a partition structure, which can partition the charge generation and separation unit 4, thereby improving color crosstalk between different light-emitting devices.

[0227] Exemplarily, the thickness of the first sub-layer 51 is between 0.01 and 0.05 μm. The thickness of the second sub-layer 52 is between 0.05 and 0.12 μm. The thickness of the third sub-layer 53 is between 0.01 and 0.05 μm. The shortest length of the first sub-layer 51 protruding from the second sub-layer 52 is between 0.2 and 1 μm, and can be selected as 0.3 to 0.5 μm. The angle γ between the side wall of the second sub-layer 52 close to the pixel opening V and the horizontal surface of the third sub-layer 53 close to the second sub-layer 52 is between 50° and 90°.

[0228] Exemplarily, the materials of the first sub-layer 51, the second sub-layer 52, and the third sub-layer 53 can be selected as inorganic, organic, and inorganic laminated materials, or multi-layer inorganic laminated materials, such as laminated materials of silicon dioxide (SiO2), silicon oxynitride (SiNx), and silicon dioxide (SiO2). The preparation process of the three-layer structure of the pixel definition layer PDL includes: first, the materials of the first sub-layer 51, the second sub-layer 52, and the third sub-layer 53 are deposited over the entire surface in sequence; then, a photoresist is coated and exposed and developed to expose the area to be etched, and the materials of the second sub-layer 52 and the third sub-layer 53 in the area to be etched are etched once to form the third sub-layer 53; then, the second sub-layer 52 material is etched a second time to form an inner concave surface and obtain the second sub-layer 52; then, the first sub-layer 51 material is etched a third time to form the first sub-layer 51; then, the photoresist is removed to obtain a barrier structure with partition ability.

[0229] In some embodiments, asFigure 6 As shown, the distance between the third surface and the first surface of the first light-emitting layer EML1 close to the anode 1 is the first distance L3; the light-emitting device is a red light-emitting device R, and the ratio of the first distance L3(R) to the microcavity length L(R) is between 0.15 and 0.4; alternatively, the light-emitting device is a green light-emitting device G, and the ratio of the thickness of the first distance L3(G) to the microcavity length L(G) is between 0.1 and 0.3; alternatively, the light-emitting device is a blue light-emitting device B, and the ratio of the thickness of the first distance L3(B) to the microcavity length L(B) is between 0.1 and 0.3. For the convenience of understanding, the above-mentioned relation (three) can also be referred to.

[0230] It should be noted that while improving the optical effect of the light-emitting device, there are relatively strict requirements for the partition process. For example, the distances from the first light-emitting layer EML1 of the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B to the anode 1 are different. If the partition structure is too high or too deep, the cathode 2 will break, and if the partition structure is too short or too shallow, it will not achieve the effect of separating the charge generation unit 4. Therefore, in the display panel of the present disclosure, by adjusting the first distance L3 between the first light-emitting layer EML1 and the anode 1, the partition process limitation of the partition structure is simplified, and at the same time, it is ensured that the first light-emitting layer EML1 of each light-emitting device is arranged at the first wave belly point of the resonance wave of the resonance microcavity, and the second light-emitting layer EML2 is arranged at the second wave belly point of the resonance wave of the resonance microcavity, ensuring the device effect.

[0231] In some embodiments, the display panel further includes a packaging layer disposed on the side of the light-emitting device away from the substrate 01, which is not only used to package the light-emitting device on the lower side, but also can be used to adjust the refractive index and improve the light extraction efficiency.

[0232] Optionally, the thickness of the packaging layer is between 5 - 80 nm, and the refractive index is greater than 1.8 at a wavelength of 460 nm.

[0233] Optionally, the packaging layer can be a single-layer or multi-layer packaging structure, such as a first inorganic packaging layer, an organic packaging layer, and a second inorganic packaging layer sequentially arranged in the direction away from the substrate 01. Among them, the first inorganic packaging layer includes one or more inorganic layers (the refractive indices of multiple layers are different), the organic packaging layer includes one or more organic layers and has a planarization function, and the second inorganic packaging layer includes one or more inorganic layers.

[0234] The first inorganic packaging layer and the second inorganic packaging layer may include at least one inorganic insulating material selected from alumina, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, and silicon oxynitride.

[0235] The organic encapsulation layer can relieve the internal stress of the first inorganic encapsulation layer and / or the second inorganic encapsulation layer. The organic encapsulation layer may include polymer materials. The polymer materials may include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate, HMDSO, acrylic resins (e.g., polymethyl methacrylate, polyacrylic acid, etc.) or any combination thereof.

[0236] In some embodiments, the display panel further includes a touch layer disposed on a side of the encapsulation layer away from the substrate 01.

[0237] Exemplarily, the display panel is a flexible display panel. To achieve the touch function of the flexible display panel, a flexible touch panel can be fabricated using the Flexible Multiple Layer On Cell (F-MLOC) process. Among them, the touch layer is disposed between the thin film encapsulation layer and the black matrix of the flexible touch panel to form a flexible touch panel with touch function.

[0238] In some embodiments, the display panel further includes a color filter layer disposed on a side of the touch layer away from the substrate 01. The color filter layer includes color filters corresponding to the light emitting devices one by one, such as a red filter corresponding to the red light emitting device R, a green filter corresponding to the green light emitting device G, and a blue filter corresponding to the blue light emitting device B.

[0239] Optionally, there is a black matrix between adjacent color filters. The black matrix can be formed by stacking multiple layers of color filters or by using black matrix materials.

[0240] The present disclosure also provides a method for manufacturing the light emitting device in the above display panel, specifically including S11 to S116.

[0241] S11. Ultrasonically treat the glass plate (substrate 01) with the anode 1 ITO in a cleaning agent, rinse it in deionized water, ultrasonically remove oil in an acetone-ethanol mixed solvent, and bake it in a clean environment until all moisture is completely removed.

[0242] S12. Place the above glass substrate with the anode 1 in a vacuum chamber, evacuate to 1×10 -5 ~1×10 -6 , and co-evaporate a hole injection material and 5% of a hole transport material on the side of the anode 1 away from the substrate 01 in vacuum to form a hole injection layer HIL.

[0243] S13. Evaporate a hole transport material on the hole injection layer HIL to form a first hole transport layer HTL1.

[0244] S14. On the first hole transport layer HTL1, deposit the first electron blocking material to form the first electron blocking layer EBL1.

[0245] S15. On the first electron blocking layer EBL1, deposit the light-emitting material to form the first light-emitting layer EML1.

[0246] S16. On the first light-emitting layer EML1, vacuum deposit the hole blocking material to form the first hole blocking layer HBL1.

[0247] S17. On the first hole blocking layer HBL1, vacuum deposit the electron transport material to form the first electron transport layer ETL1.

[0248] S18. On the first electron transport layer ETL1, deposit the N-type host material and 1% of the second dopant to form the N-type charge generation layer N-CGL.

[0249] S19. On the N-type charge generation layer N-CGL, deposit the P-type host material and 1% of the first dopant to form the P-type charge generation layer P-CGL.

[0250] S10. On the P-type charge generation layer P-CGL, deposit the hole transport material to form the second hole transport layer HTL2.

[0251] S111. On the second hole transport layer HTL2, deposit the second electron blocking material to form the second electron blocking layer EBL2.

[0252] S112. On the second electron blocking layer EBL2, deposit the light-emitting material to form the second light-emitting layer EML2.

[0253] S113. On the second light-emitting layer EML2, vacuum deposit the hole blocking material to form the second hole blocking layer HBL2.

[0254] S114. On the second hole blocking layer HBL2, vacuum deposit the electron transport material to form the second electron transport layer ETL2.

[0255] S115. On the second electron transport layer ETL2, vacuum deposit the electron injection material (with a thickness of 1 nm and the material being Yb) to form the electron injection layer EIL.

[0256] S116. On the electron injection layer EIL, deposit the MgAg(1:9) layer as the cathode 2 of the device.

[0257] The embodiments of the present disclosure further provide a display device, which includes the display panel in any one of the above embodiments. The display device may be, for example, any product with a display function such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a vehicle-mounted device, etc. Other essential components of the display device should be understood by those of ordinary skill in the art and will not be elaborated herein, nor should they be regarded as a limitation to the present disclosure.

[0258] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present disclosure. However, the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.

Claims

1. A light-emitting device, comprising an anode, a cathode, a plurality of light-emitting units disposed between the anode and the cathode, and a charge generation and separation unit disposed between adjacent light-emitting units; a resonant microcavity is formed between the anode and the cathode; the resonant microcavity comprises a plurality of antinode points; The plurality of light-emitting units at least include a first light-emitting unit and a second light-emitting unit, and the first light-emitting unit is closer to the anode than the second light-emitting unit; The first light-emitting unit includes a first light-emitting layer and a first electron blocking layer arranged on a side of the first light-emitting layer close to the anode; the second light-emitting unit includes a second light-emitting layer and a second electron blocking layer arranged on a side of the second light-emitting layer close to the anode; The first light-emitting layer is disposed at a first antinode point of the resonance wave of the resonance microcavity; the second light-emitting layer is disposed at a second antinode point of the resonance wave of the resonance microcavity; The sum of the thickness of the first light-emitting layer and the thickness of the first electron blocking layer is recorded as the first thickness; the sum of the thickness of the second light-emitting layer and the thickness of the second electron blocking layer is recorded as the second thickness; the light-emitting device is a red light-emitting device, and the ratio of the first thickness to the second thickness is between 0.6 and 1.2; or, the light-emitting device is a green light-emitting device, and the ratio of the first thickness to the second thickness is between 0.8 and 1.2; or, the light-emitting device is a blue light-emitting device, and the ratio of the first thickness to the second thickness is between 0.8 and 1.

2.

2. The light emitting device according to claim 1, wherein: The distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the microcavity length of the resonant microcavity; the distance between the third surface of the first light-emitting layer close to the anode and the first surface is the first distance; The light-emitting device is a red light-emitting device, and the ratio of the first distance to the length of the microcavity is between 0.15 and 0.4; or, the light-emitting device is a green light-emitting device, and the ratio of the thickness at the first distance to the length of the microcavity is between 0.1 and 0.3; or, the light-emitting device is a blue light-emitting device, and the ratio of the thickness at the first distance to the length of the microcavity is between 0.1 and 0.

3.

3. The light emitting device according to claim 1, wherein: The distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the microcavity length of the resonant microcavity; the distance between the fourth surface of the second light-emitting layer close to the anode and the first surface is the second distance; The light-emitting device is a red light-emitting device, and the ratio of the second distance to the length of the microcavity is between 0.5 and 0.7; or, the light-emitting device is a green light-emitting device, and the ratio of the thickness at the second distance to the length of the microcavity is between 0.55 and 0.75; or, the light-emitting device is a blue light-emitting device, and the ratio of the thickness at the second distance to the length of the microcavity is between 0.6 and 0.

8.

4. The light emitting device according to claim 1, wherein: The distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the microcavity length of the resonant microcavity; The thickness of the charge generation and separation unit is recorded as the third thickness; The light-emitting device is a red light-emitting device, and the ratio of the third thickness to the length of the microcavity is between 0.07 and 0.12; or, the light-emitting device is a green light-emitting device, and the ratio of the third thickness to the length of the microcavity is between 0.09 and 0.15; or, the light-emitting device is a blue light-emitting device, and the ratio of the third thickness to the length of the microcavity is between 0.12 and 0.

18.

5. The light emitting device according to claim 1, wherein: The light emitting device is a red light emitting device, and the thickness of the first electron blocking layer is greater than the thickness of the second electron blocking layer.

6. The light emitting device according to claim 5, wherein: The material of the second electron blocking layer is doped with an exciton capture agent; the doping concentration of the exciton capture agent is between 0.5% and 2%.

7. The light emitting device according to claim 6, wherein: The HOMO energy level of the exciton scavenger is shallower than the HOMO energy level of the second electron blocking layer; and the absolute value of the difference between the HOMO energy level of the exciton scavenger and the HOMO energy level of the second electron blocking layer is greater than or equal to 0.2 ev.

8. The light emitting device according to claim 6, wherein: The structural formula (I) of the material of the exciton scavenger is as follows: Wherein, Ra and Rb are each independently represented by a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group; Rc, Rd, Re and Rf are each independently represented by a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.

9. The light emitting device according to claim 8, wherein: The structure of the material of the exciton scavenger includes any one of the following:

10. The light emitting device according to claim 6, wherein: The material of the exciton scavenger is the same as the red guest material of the second light-emitting layer.

11. The light emitting device according to claim 1, wherein: The light emitting device is a red light emitting device, and the thickness of the second light emitting layer is greater than or equal to the thickness of the first light emitting layer.

12. The light emitting device according to claim 11, wherein: The material of the second light-emitting layer includes a red host material and a red guest material; the red host material includes a P-type material and an N-type material; the doping concentration of the P-type material is greater than or equal to the doping concentration of the N-type material.

13. The light emitting device according to claim 11, wherein: The material of the first light-emitting layer is different from the material of the second light-emitting layer; and the mobility of the second light-emitting layer is greater than the mobility of the first light-emitting layer.

14. The light emitting device according to claim 1, wherein: The charge generation and separation unit comprises an N-type charge generation layer and a P-type charge generation layer arranged in sequence in a direction from the anode to the cathode; The first light-emitting unit further includes a hole injection layer disposed on the anode close to the first electron blocking layer, a first hole transport layer disposed on the hole injection layer close to the first electron blocking layer, a first hole blocking layer disposed on the first light-emitting layer close to the N-type charge generation layer, and a first electron transport layer disposed on the first hole blocking layer close to the N-type charge generation layer. The second light-emitting unit also includes an electron injection layer, a second electron transport layer and a second hole blocking layer arranged in sequence on the cathode along the direction pointing from the cathode to the second light-emitting layer, and a second hole transport layer arranged between the second electron blocking layer and the P-type charge generation layer.

15. The light emitting device according to claim 14, wherein: The absolute value of the difference between the HOMO energy level of the P-type charge generation layer and the HOMO energy level of the second hole transport layer is less than or equal to 0.3 ev; the absolute value of the difference between the lowest unoccupied molecular orbital LUMO energy level of the N-type charge generation layer and the LUMO energy level of the first hole blocking layer is less than or equal to 0.5 ev; The absolute value of the difference between the HOMO energy level of the first hole transport layer and the HOMO energy level of the first electron blocking layer ranges from 0.1ev to 0.4ev; the absolute value of the difference between the HOMO energy level of the second hole transport layer and the HOMO energy level of the second electron blocking layer ranges from 0.1ev to 0.4ev.

16. The light emitting device according to claim 14, wherein: The material of the first hole transport layer is different from the material of the second hole transport layer; and the mobility of the first hole transport layer is greater than the mobility of the second hole transport layer.

17. The light emitting device according to claim 14, wherein: The P-type charge generation layer is doped with a material represented by structural formula (II) or structural formula (III); The general structural formula (II) is as follows: Wherein, A1-A6 are each independently represented by substituted or unsubstituted halogen, substituted or unsubstituted cyano, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; when A1-A6 are each independently represented by a substituent being an aryl, the aryl may be substituted by an electron withdrawing group; A is represented by a 3-membered ring, a 4-membered ring, a 5-membered ring, or a 6-membered ring; The general structural formula (III) is as follows: wherein X1 and X2 are each independently represented by one of C, N, and Si; Y1 and Y2 are each independently represented by one of O, N, and S; Ar1-Ar4 are each independently represented by substituted or unsubstituted halogen, substituted or unsubstituted cyano, substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted fluorene, substituted or unsubstituted adamantane, or substituted or unsubstituted heteroaryl; R1 and R2 are each independently represented by deuterium, a halogen group, a cyano group, a substituted or unsubstituted heteroaryl group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms; a and b are each independently an integer of 1 to 5.

18. The light emitting device according to claim 14, wherein: The N-type main material of the N-type charge generation layer is a material represented by the structural formula (IV); The general structural formula (IV) is as follows: wherein X1-X4 are each independently represented by N or C(R1), and X1-X4 each independently contain at least 2 N; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-C60 alkynyl, substituted or unsubstituted C1-C60 alkoxy, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C1-C10 heterocycloalkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocycloalkenyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C6-C60 arylthio, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, substituted or unsubstituted monovalent Non-aromatic condensed heteropolycyclic group; Ar1, Ar2, Ar3, Ar4 are the same or different and each independently represents one selected from the following: hydrogen, deuterium, tritium, halogen, cyano, nitro, C6-C60 aryl, C2-C60 heterocyclic group containing at least one heteroatom from O, N, S, Si and P, C3-C60 aliphatic ring, condensed ring group of C6-C60 aromatic ring, C1-C50 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C30 alkoxy, C6-C30 aryloxy, C3-C60 alkylsilyl, C18-C60 arylsilyl, C8-C60 alkylarylsilyl.

19. The light emitting device according to any one of claims 1 to 18, wherein: The distance between the first surface of the anode close to the cathode and the second surface of the cathode close to the anode is the microcavity length of the resonant microcavity; The light-emitting device is a red light-emitting device, and the length of the microcavity is between 2500 angstroms and 3000 angstroms; or, the light-emitting device is a green light-emitting device, and the length of the microcavity is between 2500 angstroms and 2600 angstroms; or, the light-emitting device is a blue light-emitting device, and the length of the microcavity is between 1500 angstroms and 2000 angstroms.

20. The light emitting device according to claim 1, wherein: The first light-emitting layer and the second light-emitting layer are made of the same material; The material of the first light-emitting layer includes a light-emitting host material and a light-emitting guest material; the light-emitting host material is an exciplex.

21. The light emitting device according to claim 1, wherein: The light emitting device is a blue light emitting device; The triplet energy level of the first hole blocking layer is greater than the triplet energy level of the blue main material of the first luminescent material; the triplet energy level of the first electron blocking layer is greater than the triplet energy level of the blue main material of the first luminescent material.

22. A display panel, wherein: The invention comprises the light emitting device according to any one of claims 1 to 21.

23. The display panel according to claim 11, wherein: The display panel further comprises a partition structure arranged between two adjacent light emitting devices; the two light emitting devices emit light of different colors, and the charge generation and separation units of the two light emitting devices are partitioned at the position of the partition structure.

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