Light emitting device and display panel

Abstract

The present disclosure provides a light-emitting device and a display panel, and belongs to the technical field of display. The light-emitting device of the present disclosure forms a resonant microcavity between an anode and a 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 anti-node point of a resonant wave of the resonant microcavity; the second light-emitting layer is arranged at a second anti-node point of the resonant wave of the resonant 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, 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, 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, the ratio of the first thickness to the second thickness is between 0.8 and 1.2.

Description

Technical Field

[0001] This disclosure belongs to the field of organic semiconductor and display technology, and specifically relates to a light-emitting device and a display panel. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are light-emitting devices that use organic solid-state semiconductors as light-emitting materials. They are characterized by self-illumination, no need for a backlight, thin panel thickness, and light weight. OLEDs also offer numerous advantages such as wide viewing angle, high contrast, fast response, wide operating temperature range, and flexibility.

[0003] To achieve higher current efficiency, multiple light-emitting units can be stacked, with adjacent units connected by a charge generation layer (CGL). OLEDs with multiple stacked light-emitting units are typically called tandem OLEDs (or Tandem devices). Tandem OLEDs have broad application prospects due to their higher efficiency and longer lifespan compared to traditional OLEDs. Summary of the Invention

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

[0005] Firstly, the technical solution adopted to solve the technical problem of this disclosure is a light-emitting device, including 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 includes a plurality of antinodes;

[0006] The plurality of light-emitting units include at least a first light-emitting unit and a second light-emitting unit, wherein 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 the side of the first light-emitting layer near the anode; the second light-emitting unit includes a second light-emitting layer and a second electron blocking layer disposed on the side of the second light-emitting layer near the anode;

[0008] The first light-emitting layer is disposed at the first antinode of the resonant wave of the resonant microcavity; the second light-emitting layer is disposed at the second antinode 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 near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; the distance between the third surface of the first light-emitting layer near 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 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 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 length of the microcavity is between 0.1 and 0.3.

[0012] In some embodiments, the distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; the distance between the fourth surface of the second light-emitting layer near 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 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 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 length of the microcavity is between 0.6 and 0.8.

[0014] In some embodiments, the distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; the thickness of the charge generation 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 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.

[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, the material of the second electron blocking layer is doped with an exciton trapping agent; the doping concentration of the exciton trapping agent is between 0.5% and 2%.

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

[0019] In some embodiments, the exciton trapping agent material has the following general structural formula (I):

[0020]

[0021] In this context, Ra and Rb are each independently represented as substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl; Rc, Rd, Re and Rf are each independently represented as substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

[0022] In some embodiments, the exciton trapping agent material comprises any of the following structures:

[0023]

[0024]

[0025]

[0026] In some embodiments, the material of the exciton trapping agent is the same as the red guest material of the second luminescent 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 separation unit includes an N-type charge generation layer and a P-type charge generation layer sequentially disposed 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 the side of the hole injection layer near the first electron blocking layer, a first hole blocking layer disposed on the side of the first light-emitting layer near the N-type charge generation layer, and a first electron transport layer disposed on the 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 sequentially disposed 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 generating 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 is in the range of 0.1 eV to 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 is in the range of 0.1 eV to 0.4 eV.

[0035] In some embodiments, the material of the first hole transport layer is different from that of the second hole transport layer; the mobility of the first hole transport layer is greater than that 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, a substituted or unsubstituted aryl, or a substituted or unsubstituted heteroaryl; when each of A1-A6 independently represents an aryl substituent, the aryl is substituted by an electron-withdrawing group; A represents a 3-membered ring, a 4-membered ring, a 5-membered ring, or a 6-membered ring;

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

[0041]

[0042] In this context, X1 and X2 are each independently represented by one of C, N, or Si; Y1 and Y2 are each independently represented by one of O, N, or S; Ar1-Ar4 are each independently represented by 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 are each independently represented by 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, or a substituted or unsubstituted aryl group. Alkyl groups with 1 to 5 substituted or unsubstituted carbon atoms, haloalkyl groups with 1 to 10 substituted or unsubstituted carbon atoms, cycloalkyl groups with 3 to 10 substituted or unsubstituted carbon atoms, heterocycloalkyl groups with 2 to 10 substituted or unsubstituted carbon atoms, alkoxy groups with 1 to 10 substituted or unsubstituted carbon atoms, alkylthio groups with 1 to 10 substituted or unsubstituted carbon atoms, aryloxy groups with 6 to 18 substituted or unsubstituted carbon atoms, arylthio groups with 6 to 18 carbon atoms, phosphoroxy groups with 6 to 24 carbon atoms, and alkylsulfonyl groups with 6 to 18 substituted or unsubstituted carbon atoms; a and b are each independently represented as integers 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 (four) is as follows:

[0045]

[0046] Wherein, X1-X4 are each independently represented as N or C(R1), and each of X1-X4 independently contains at least 2 N atoms; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-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, substituted or unsubstituted monovalent Non-aromatic condensed heterocyclic groups; Ar1, Ar2, Ar3, and Ar4 may be the same or different, and each is independently represented as selected from one of 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, C6-C60 aromatic ring fused ring group, C1-C50 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C30 alkoxy, C6-C30 aryloxy, C3-C60 alkylsilyl, C18-C60 arylsilyl, and C8-C60 alkylarylsilyl.

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

[0048] 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.

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

[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 excimer complex.

[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 the triplet energy level of the blue host 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 host material of the first luminescent material.

[0053] Secondly, embodiments of this disclosure also provide a display panel, wherein the light-emitting device is included as described in any one of the first aspects.

[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 separated at the location of each partition structure. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of OLEDs connected in series.

[0056] Figure 2 This is a schematic diagram illustrating the light-emitting principle of OLEDs connected in series.

[0057] Figure 3 This is a schematic diagram of a light-emitting device provided in an embodiment of this disclosure.

[0058] Figure 4 This is a schematic diagram of the structural dimensions of the light-emitting device provided in the embodiments of this disclosure.

[0059] Figure 5 This is a schematic diagram comparing the energy level relationships of red and green light-emitting devices provided in embodiments of this disclosure.

[0060] Figure 6 This is a schematic diagram of a plurality of light-emitting devices in a display panel provided in an embodiment of the present disclosure.

[0061] Figure 7 This is a schematic diagram of the partition structure in Example 1 of the display panel provided in an embodiment of this disclosure.

[0062] Figure 8 This is a schematic diagram of the partition structure in Example 2 of the display panel provided in the embodiments of this disclosure.

[0063] Figure 9 This is a schematic diagram of the partition structure in Example 3 of the display panel provided in the embodiments of this disclosure.

[0064] Figure 10 for Figure 9 Enlarged view of the central partition structure. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Unless otherwise defined, the technical or scientific terms used in this disclosure should have the ordinary meaning understood by those skilled in the art to which this disclosure pertains. The terms "first," "second," and similar words used in this disclosure do not indicate any order, quantity, or importance, but are only used to distinguish different components. "Up," "down," "left," "right," etc., are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. "Multiple or several" mentioned in this disclosure refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0066] Figure 1 This is a schematic diagram of OLEDs connected in series. Figure 2 This is a schematic diagram illustrating the light-emitting principle of OLEDs connected in series. Figure 1 and Figure 2 As shown, the tandem OLED includes an anode 1, a cathode 2, multiple 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. This disclosure uses a two-layer light-emitting unit as an example, referred to as a first light-emitting unit 31 and a second light-emitting unit 32. 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 for assisting carrier transport; 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 for assisting carrier transport. The charge generation and separation unit 4 generates holes and electrons (collectively referred to as carriers) and separates them, injecting them respectively into the second light-emitting layer EML2 side and the first light-emitting layer EML1 side. During this process, the functional layers assisting carrier transport can better transport carriers, allowing carriers to fully recombine in the light-emitting layer EML. In tandem OLEDs, the three processes of efficiently generating charge, rapidly transporting charge, and effectively injecting charge are all indispensable and have a significant impact on device performance. Therefore, how to rationally combine the light-emitting unit and the charge generation separation unit 4 to ensure efficient generation, injection, and transport of charge carriers has become a problem that urgently needs to be solved in the fields of organic semiconductors and display technology.

[0067] Therefore, embodiments of this disclosure provide a light-emitting device. Figure 3 This is a schematic diagram of a light-emitting device provided in an embodiment of this disclosure. Figure 4This is a schematic diagram of the structural dimensions of the light-emitting device provided in the embodiments of this disclosure.

[0068] like Figure 3 As shown, the light-emitting device includes an anode 1, a cathode 2, multiple 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 multiple light-emitting units include at least a first light-emitting unit 31 and a second light-emitting unit 32, with the first light-emitting unit 31 being closer to the anode 1 than the second light-emitting unit 32. This disclosure uses two light-emitting units as an example, but in practice, it may include more than two light-emitting units, and a charge generation separation unit 4 is disposed between adjacent light-emitting units.

[0069] like Figure 4 As shown, a resonant microcavity is formed between the anode 1 and the cathode 2. The resonant microcavity includes multiple antinodes. Exemplarily, the light-emitting device of this disclosure is an OLED device. Since the light-emitting device of this disclosure includes multiple light-emitting units, the light-emitting device of this disclosure is a series OLED. Each light-emitting unit in the series OLED has its own light-emitting layer EML. The first light-emitting unit 31 has a first light-emitting layer EML1, and the second light-emitting unit 32 has a second light-emitting layer EML2. The first light-emitting layer EML1 is driven by the 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 the holes and electrons generated by the charge generation separation unit 4 and the cathode 2, respectively. Therefore, the series OLED forms multiple optical cavities, which are collectively referred to as resonant microcavities in this disclosure. Each optical cavity resonates, thereby generating multiple antinodes. In this disclosure, the first light-emitting layer EML1 is disposed at the first antinode of the resonant wave of the resonant microcavity, and the second light-emitting layer EML2 is disposed at the second antinode of the resonant wave of the resonant microcavity. Resonant microcavities can increase the photon density near the antinodes of the emissive layer (EML) by enhancing the light field intensity at a specific wavelength, thereby improving luminous efficiency. At the same time, the enhanced light field intensity can reduce the driving voltage required to achieve the same brightness, thus reducing power consumption. The light field intensity is greatest near the antinodes, which helps more photons escape from the device, reducing internal losses and improving light extraction efficiency. In addition, the enhanced light field intensity can reduce the driving voltage required to achieve the same brightness, thereby reducing power consumption and improving the performance of tandem OLED devices.

[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 near 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 near 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 ease of understanding, please refer to the following relationship (I).

[0071] Relation (1):

[0072] This embodiment optimizes the light emission position by adjusting the thickness of the emissive layer EML and the electron blocking layer EBL. While ensuring that the emissive layer EML is located near the antinode (microcavity reinforcement region), it further enhances the superposition effect of the upper and lower emissive layers EML. For example, by setting the ratio of the total thickness of the first emissive layer EML1 and the first electron blocking layer EBL1 (first thickness L1) of the red light-emitting device R to the total thickness of the second emissive layer EML2 and the second electron blocking layer EBL2 (second thickness L2), ensuring that this ratio is between 0.6 and 1.2, the superposition light emission effect of the first emissive layer EML1 and the second emissive layer EML2 of the red light-emitting device R can be improved. By setting the ratio of the total thickness of the first emitting layer EML1 and the first electron blocking layer EBL1 (first thickness L1) of the green light-emitting device G to the total thickness of the second emitting layer EML2 and the second electron blocking layer EBL2 (second thickness L2), ensuring that this ratio is between 0.8 and 1.2, the superimposed light emission effect of the first emitting layer EML1 and the second emitting layer EML2 of the green light-emitting device G can be improved. Similarly, by setting the ratio of the total thickness of the first emitting layer EML1 and the first electron blocking layer EBL1 (first thickness L1) of the blue light-emitting device B to the total thickness of the second emitting layer EML2 and the second electron blocking layer EBL2 (second thickness L2), ensuring that this ratio is between 0.8 and 1.2, the superimposed light emission effect of the first emitting layer EML1 and the second emitting layer EML2 of the blue light-emitting device B can be improved.

[0073] For example, 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 examples, and the above-mentioned thickness ratio of the red light-emitting device R is not limited to these listed cases. Any value between 0.6 and 1.2 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0074] For example, 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 examples, and the above-mentioned thickness ratio of the green light-emitting device G is not limited to these listed cases. Any value between 0.8 and 1.2 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0075] For example, 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 examples, and the above-mentioned thickness ratio of the blue light-emitting device B is not limited to these listed cases. Any value between 0.8 and 1.2 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0076] In some embodiments, such as Figure 4 As shown, the distance between the first surface of anode 1 near cathode 2 and the second surface of cathode 2 near anode 1 is the cavity length L of the resonant microcavity. The light-emitting device is a red light-emitting device R, with a cavity length L(R) ranging from 2500 Å to 3000 Å; or, the light-emitting device is a green light-emitting device G, with a cavity length L(G) ranging from 2500 Å to 2600 Å; or, the light-emitting device is a blue light-emitting device B, with a cavity length L(B) ranging from 1500 Å to 2000 Å. For easier understanding, please refer to the following relationship (II).

[0077] Relationship (II):

[0078] This embodiment optimizes the total thickness of the tandem OLED devices by adjusting the cavity length of the resonant microcavity, ensuring that the light emission positions of the red light-emitting device R, the green light-emitting device G, or the blue light-emitting device B are all located near their respective antinodes (microcavity reinforcement region), thereby improving the light extraction efficiency of the tandem OLED devices.

[0079] In some embodiments, such as Figure 4As shown, the distance between the third surface of the first light-emitting layer EML1 near the anode 1 and the first surface 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; or, 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; or, 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 ease of understanding, please refer to the following relationship (III).

[0080] Relationship (3):

[0081] For example, 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 examples, and the above ratios of the red light-emitting device R are not limited to these listed cases. Any value between 0.15 and 0.4 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0082] For example, 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 examples, and the above ratios of the green light-emitting device G are not limited to these listed cases. Any value between 0.1 and 0.3 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0083] For example, 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 examples, and the above ratios of the blue light-emitting device B are not limited to these listed cases. Any value between 0.1 and 0.3 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0084] This embodiment optimizes the position of the first light-emitting layer EML1 by adjusting the first distance L3 between the first light-emitting layer EML1 and the anode 1, ensuring that the first light-emitting layer EML1 is located near the antinode (microcavity reinforcement 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 of the second light-emitting layer EML2 near the anode 1 and the first surface 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; or, 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; or, 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 easier understanding, please refer to the following relationship (IV).

[0086] Relationship (IV):

[0087] For example, 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 examples, and the above ratios of the red light-emitting device R are not limited to these listed cases. Any value between 0.5 and 0.7 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0088] For example, 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 examples, and the above ratios of the green light-emitting device G are not limited to these listed cases. Any value between 0.55 and 0.75 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0089] For example, 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 examples, and the above ratios of the blue light-emitting device B are not limited to these listed cases. Any value between 0.6 and 0.8 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0090] In this embodiment, by adjusting the second distance L4 between the second light-emitting layer EML2 and the anode 1, the position of the second light-emitting layer EML2 is optimized, ensuring that the second light-emitting layer EML2 is located near the antinode (microcavity reinforcement 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 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; or, 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; or, 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 easier understanding, please refer to the following relationship (V).

[0092] Relationship (5):

[0093] For example, 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 examples, and the above ratios of the red light-emitting device R are not limited to these listed cases. Any value between 0.07 and 0.12 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0094] For example, 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 examples, and the above ratios of the green light-emitting device G are not limited to these listed cases. Any value between 0.09 and 0.15 falls within the protection scope of this disclosure, and will not be listed one by one here.

[0095] For example, 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 examples; the ratios of the blue light-emitting device B are not limited to these listed cases. Any value between 0.12 and 0.18 falls within the protection scope of this disclosure, and will not be listed in detail here.

[0096] This embodiment adjusts the position of the charge generation separation unit 4 to ensure that when preparing the isolation structure in the display panel (see the subsequent description of the display panel structure, which will not be detailed here), the charge generation separation unit 4 of adjacent light-emitting devices can be completely isolated while ensuring the overall continuity of the cathode 2. This improves the crosstalk phenomenon between different pixels, reduces the voltage of the device, and ensures 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 upon the tandem red OLED. A first electron blocking layer (EBL1) is disposed between the first emitting layer (EML1) and the anode 1, primarily blocking electrons entering the first EML1 from the anode 1 side. A second electron blocking layer (EBL2) is disposed between the second EML2 and the charge generation separation unit 4, primarily blocking electrons entering the second EML2 from the charge generation separation unit 4 side. Since the charge generation separation unit 4 has a stronger ability to generate holes and electrons than the anode 1 and cathode 2, increasing the thickness of the first electron blocking layer (EBL1) helps prevent excess electrons from entering the first EML1, thus promoting a more uniform carrier distribution on the first EML1 and ensuring the exciton recombination region is located at the center of the first EML1, thereby 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 trapper. An exciton trapper is a material that can trap holes. By trapping excess holes in the electron blocking layer EBL, excessive holes can be prevented from entering the light-emitting layer EML, which would lead to a significant decrease in device efficiency.

[0100] Optionally, the doping concentration of the exciton trapper is between 0.5% and 2%. Here, "doping concentration" refers to the mass ratio, such as the mass ratio of the exciton trapper to the mass of the electron blocking layer (EBL) material.

[0101] Optionally, the HOMO level of the exciton trap is shallower than that 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 achieve uniform carrier distribution on the second emitting layer EML2, ensuring that the exciton recombination region is located in the center of the second emitting layer EML2, which is 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 trapper 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 trapper)-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 the thickness of the second electron blocking layer EBL2. At the same time, the second electron blocking layer EBL2 is doped with an exciton trapper, and the HOMO energy level of the exciton trapper is shallower than the HOMO energy level of the second electron blocking layer EBL2. This can simultaneously and uniformly distribute the charge of the first light-emitting layer EML1 and the second light-emitting layer EML2, ensuring that the exciton recombination center of the two is close to the center of the light-emitting layer EML, avoiding cross-color and crosstalk between the first light-emitting layer EML1 and the second light-emitting layer EML2, which is beneficial to improving the overall luminous efficiency and lifetime of the series-connected red OLED.

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

[0105] General structural formula (I):

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

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

[0108]

[0109]

[0110] Alternatively, the exciton trapping agent can be made of the material corresponding to the structure in general formula (I) above, or it can be the same as the red guest material RD of the second luminescent layer EML2. The red guest material RD is described in the following description and will not be detailed 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 the thickness of the first light-emitting layer EML1.

[0112] Optionally, the thickness of the second light-emitting layer EML2 is greater than the thickness 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 widened, thereby improving the degradation of the material at the interface by high-energy excitons and thus improving the lifetime 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 first emitting layer EML1 and the second emitting layer EML2 are made of the same material. The material of the second emitting layer EML2 includes a red host material RH and a red guest material RD, wherein the red host material RH includes P-type material and 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. For example, the mass ratio of the P-type material to the N-type material is between 1:1 and 9:1. In this disclosure, based on 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, thereby adjusting the holes captured by the second electron blocking layer EBL2 (referring to the second electron blocking layer EBL2 doped with an exciton trapper), further ensuring the balance of charge carriers in the second emitting layer EML2.

[0115] Optionally, the first light-emitting layer EML1 and the second light-emitting layer EML2 are made of different materials. By setting the mobility of the second light-emitting layer EML2 to be greater than that of the first light-emitting layer EML1, the increase in device voltage caused by the increased thickness of the second light-emitting layer EML2 can be mitigated.

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

[0117] The following section details the functional layers used to assist carrier transport in terms of energy levels, mobility, and material properties. By rationally adjusting the combination of the properties of different functional layers, we can ensure the efficient generation, injection, and transport of carriers, thereby improving the overall performance of the tandem OLED.

[0118] Regarding 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, i.e., |LUMO(N-CGL)-LUMO(HBL1)|≤0.5 eV. This reduces the energy level transport barrier, allowing 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, i.e., |HOMO(P-CGL)-HOMO(HTL2)|≤0.3 eV. This reduces the energy level transport barrier, allowing holes to be effectively injected into the adjacent second emitting layer EML2.

[0119] The absolute value of the difference between the HOMO level of the first hole transport layer HTL1 and the HOMO level of the first electron blocking layer EBL1 ranges from 0.1 eV to 0.4 eV, i.e., 0.1 eV ≤ |HOMO(HTL1) - HOMO(EBL1)| ≤ 0.4 eV; the absolute value of the difference between the HOMO level of the second hole transport layer HTL2 and the HOMO level of the second electron blocking layer EBL2 ranges from 0.1 eV to 0.4 eV, i.e., 0.1 eV ≤ |HOMO(HTL2) - HOMO(EBL2)| ≤ 0.4 eV. This eliminates the problem of slow hole transport caused by the energy level barrier, and accelerates hole transport to a certain extent.

[0120] The following describes individual light-emitting devices. It is particularly emphasized that organic functional layers without the designations "first" and "second" generally refer to both first and second organic functional layers. When comparing parameters (such as energy levels), the comparison is made between layers located within the same light-emitting unit; that is, first layers are compared with first layers, and second layers with second layers. For example, hole transport layer HTL generally refers to first hole transport layer HTL1 and second hole transport layer HTL2; electron blocking layer EBL generally refers to first electron blocking layer EBL1 and second electron blocking layer EBL2; hole blocking layer HBL generally refers to first hole blocking layer HBL1 and second hole blocking layer HBL2; electron transport layer ETL generally refers to first electron transport layer ETL1 and second electron transport layer ETL2; and light-emitting layer EML generally refers to first light-emitting layer EML1 and second light-emitting layer EML2.

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

[0122] For the blue light-emitting device B, the material of the emissive layer EML includes a host material and a guest material, where the host material is either a single host or an excimer compound. Taking the blue host material as an example, the absolute value of the difference between the HOMO energy level of the blue host (BH) and the HOMO energy level of the electron blocking layer EBL is less than or equal to 0.3 eV, i.e., |HOMO(BH)-HOMO(EBL)|≤0.3 eV. By setting a smaller HOMO band gap, hole transport is facilitated. Similarly, the absolute value of the difference between the LUMO energy level of the hole blocking layer HBL and the LUMO energy level of the blue host is less than or equal to 0.3 eV, i.e., |LUMO(HBL)-LUMO(BH)|≤0.3 eV. By setting a smaller LUMO band gap, electron transport is facilitated.

[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. Thus, when the blue light-emitting layer EML emits fluorescence, satisfying the above conditions can fully utilize the TTA mechanism, improve exciton utilization, and thereby improve the efficiency of the blue OLED device.

[0124] Energy level relationship between red light-emitting device R and green light-emitting device G Figure 5 This is a schematic diagram comparing the energy level relationship between the red light-emitting device R and the green light-emitting device G provided in the embodiments of this disclosure, as shown below. Figure 5 As shown, the HOMO level of the P-type material P-RH of the red light-emitting device R is shallower than the HOMO level of the P-type material P-GH of the green light-emitting device G, and the LUMO level of the N-type material N-RH of the red light-emitting device R is deeper than the LUMO level of the N-type material N-GH of the green light-emitting device G.

[0125] When the light-emitting device design of the present disclosure meets the above conditions, holes and electrons can recombine and emit light in the light-emitting layer EML. At the same time, adjusting the transport rate of holes and electrons is beneficial to the balance of charge carriers in the exciton recombination region, so that the exciton recombination region is away from the side of the electron blocking layer EBL.

[0126] Regarding mobility: Taking the case where the thickness of the second light-emitting layer EML2 is greater than that 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. The mobility of the light-emitting main material of the second light-emitting layer EML2 is greater than that of the light-emitting main 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 that of the second hole transport layer HTL2; the mobility of the first hole transport layer HTL1 is greater than that of the second hole transport layer HTL2, which is beneficial to hole transport and further reduces the operating voltage of the device.

[0128] The ratio of hole mobility to electron mobility in the material of the light-emitting layer (EML) is between 0.01 and 100.

[0129] Regarding materials: For the red light-emitting device R, the emissive layer EML consists of a red host material RH (light-emitting host material) and a red guest material RD (light-emitting guest material). The red host material RH can be an exciton complex. This exciton complex can be used to regulate the carrier balance in the emissive layer EML, effectively controlling the exciton recombination region to be located at the center of the EML. This increases exciton utilization and thus improves the overall luminous efficiency of the tandem red OLED. For example, the red host material RH can be a hole-biased material. This ensures red light emission while simultaneously transferring holes to the emissive layer EML of the green light-emitting device G, facilitating radiation emission from the green device G. The red guest material RD can be a phosphorescent dopant.

[0130] For a green light-emitting device G, the materials of the emissive layer EML include a green host material GH (emissive host material) and a green guest material GD (emissive guest material). The green host material GH can be selected from exciton complexes. These exciton complexes can be used to regulate the carrier balance in the emissive layer EML, thereby effectively controlling the exciton recombination region to be located at the center of the emissive layer EML. This is beneficial for increasing exciton utilization and thus improving the overall luminous efficiency of the tandem green OLED. The green guest material GD can be selected from phosphorescent dopants.

[0131] For the blue light-emitting device B, the material of the light-emitting layer EML includes a blue host material BH (light-emitting host material) and a blue guest material BD (light-emitting guest material). The blue host material BH can be a single host or an excimer compound. For example, 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. As another example, when the blue host material BH is an excimer compound, 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 material of the P-type charge generation layer P-CGL includes 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. Optionally, the first dopant can be a material represented by structural formula (ii) or structural formula (iii).

[0133] General structural formula (II):

[0134] In this context, A1-A6 can be independently represented as 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 can be independently represented as an aryl group, the aryl group can be substituted by an electron-withdrawing group. A can be represented as a 3-membered ring, a 4-membered ring, a 5-membered ring, or a 6-membered ring.

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

[0136]

[0137] General structural formula (III):

[0138] In this context, X1 and X2 are each independently represented by one of C, N, or Si; Y1 and Y2 are each independently represented by one of O, N, or S; Ar1-Ar4 are each independently represented by 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 are each independently represented by 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, or a substituted or unsubstituted aryl group. Alkyl groups with 1 to 5 substituted or unsubstituted carbon atoms, haloalkyl groups with 1 to 10 substituted or unsubstituted carbon atoms, cycloalkyl groups with 3 to 10 substituted or unsubstituted carbon atoms, heterocycloalkyl groups with 2 to 10 substituted or unsubstituted carbon atoms, alkoxy groups with 1 to 10 substituted or unsubstituted carbon atoms, alkylthio groups with 1 to 10 substituted or unsubstituted carbon atoms, aryloxy groups with 6 to 18 substituted or unsubstituted carbon atoms, arylthio groups with 6 to 18 carbon atoms, phosphoroxy groups with 6 to 24 carbon atoms, and alkylsulfonyl groups with 6 to 18 substituted or unsubstituted carbon atoms; a and b are each independently represented as integers from 1 to 5.

[0139] Among them, the compound in general 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 that is conducive to hole transport through a co-evaporation process, thereby ensuring the effective generation and efficient transport of holes.

[0140] For example, the structure of the first dopant shown in general 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 can be a material represented by the general structural formula (iv). The second dopant can be selected from alkali metals and their compounds such as lithium (Li), sodium (Na), potassium (K) or cesium (Cs), or alkali 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] General structural formula (IV):

[0145] Wherein, X1-X4 are each independently represented as N or C(R1), and each of X1-X4 independently contains at least 2 N atoms; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-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, substituted or unsubstituted monovalent Non-aromatic condensed heterocyclic groups; Ar1, Ar2, Ar3, and Ar4 may be the same or different, and each is independently represented as selected from one of 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, C6-C60 aromatic ring fused ring group, C1-C50 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C30 alkoxy, C6-C30 aryloxy, C3-C60 alkylsilyl, C18-C60 arylsilyl, and C8-C60 alkylarylsilyl.

[0146] Among them, the heterocyclic compound represented by the general structural formula (iv) has a deep LUMO energy level, which reduces the potential barrier at the interface between the N-type charge generation layer N-CGL and the P-type charge generation layer P-CGL, thereby suppressing the degradation at the interface caused by the accumulation of charge carriers due to the energy level barrier.

[0147] Furthermore, the heterocyclic compounds represented by general structural formula (iv) also possess sp2-hybridized nitrogen (N) atoms, giving them excellent electron transport capabilities. This allows the electron flow generated by the PN (pin) 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. Simultaneously, the lone pairs of electrons from the sp2-hybridized N atoms can form complexes with the active metal compounds in the N-type charge generation layer N-CGL. This suppresses crystallization of the material represented by general structural formula (iv) and increases the electron injection capability of the N-type charge generation layer N-CGL, controlling crystallization at the interface between the first electron transport layer ETL1 and the N-type charge generation layer N-CGL, thus improving the uniformity of the interface morphology. In this way, charge flow in the OLED device can be improved, thereby reducing the driving voltage.

[0148] For example, the structure of the first dopant shown in general formula (iv) includes any one of the following (4-1 to 4-18).

[0149]

[0150]

[0151] In some embodiments, such as Figure 3 As shown, the materials for each functional layer can also be the following examples.

[0152] Optionally, the anode 1 can be a high work function electrode material, such as transparent oxide ITO or 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, or triaxial compounds. Among them, the structural formula of HATCN is... The structural formula of F4TCNQ is: The structural formula of PPDN is The structural formula of triaxial compounds is as follows:

[0155] Alternatively, the hole injection layer HIL can be formed by p-type doping of the hole transport material. The thickness of the hole injection layer HIL is between 5 and 20 nm. The hole injection layer HIL can be formed by co-evaporation of the hole transport material and the p-type dopant.

[0156] Optionally, the hole transport layer (HTL) is mainly used for hole transport. The material of the HTL needs to have good hole transport characteristics, such as aromatic amines or carbazoles, like NPB, TCTA, TAPC, TPD, BAFLP, and DFLDPBi. 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 within the emissive layer EML, preventing exciton leakage to both sides of the EML and thus avoiding efficiency loss. It also possesses good hole transport characteristics and can be made of aromatic amines or carbazole materials, such as CBP or PCzPA. The material of the second electron blocking layer EBL2 is based on the material of the first electron blocking layer EBL1, doped with an exciton trapping agent. The specific structure of this exciton trapping agent is shown in general structural formula (I). The exciton trapping agent is mainly used to trap excess charge carriers in the second electron blocking layer EBL2, preventing excessive holes from entering the emissive layer EML and causing a significant decrease in device efficiency. Therefore, it can be set to a material with a HOMO energy level shallower than that 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 body material RH can be selected from the DCM series materials, such as DCM, DCJTB, DCJTI, etc. The selected red body material RH is DCzDBT, whose structural formula is... Alternatively, the red main material RH can be selected as a P-type material. Alternatively, the red main material RH can be selected as 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 coumarin dyes, quinacrine copper derivatives, polycyclic aromatic hydrocarbons, diamine anthracene derivatives, and carbazole derivatives, such as DMQA, BA-NPB, and Alq3. CBP is selected as the green host material GH, and its structural formula is... Alternatively, the green main material GH can be selected as a P-type material. Alternatively, the green main material GH can be selected as an N-type material. Green guest materials (GD) can be metal complexes, such as Ir(ppy)3 and Ir(ppy)2(acac). The structural formula of Ir(ppy)3 is...

[0161] Optionally, the blue host material BH can be selected from anthracene derivatives such as ADN and MADN. The structural formula of AND is... The blue guest material BD can be a pyrene derivative, fluorene derivative, perylene derivative, styrene-amine derivative, or metal complex, such as TBPe, BDAVBi, DPAVBi, and FIrpic. Among them, the structural formula of DPAVBi is... Alternatively, choose the blue object material BD.

[0162] Optionally, the materials for the hole blocking layer (HBL) and the electron transport layer (ETL) can be aromatic heterocyclic compounds, such as imidazole derivatives, imidazopyridine derivatives, benzimidazole-phenanthridine derivatives, and other imidazole derivatives; pyrimidine derivatives, triazine derivatives, and other azine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthrene derivatives, and other compounds containing a nitrogen-containing six-membered ring structure (including compounds with phosphine oxide substituents on the heterocycle, such as OXD-7, TAZ, p-EtTAZ, BPhen, BCP, etc.).

[0163] For example, the material of the hole blocking layer HBL is The material for the electron transport layer (ETL) can be 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 a hole-type material, such as NPB or TPD, wherein the structural formula of NPB is as follows: The first dopant of the P-type charge generation layer P-CGL can be HATCN, F4TCNQ, PPDN, or triaxial compounds, etc.; among which, the structural formula of HATCN is... The structural formula of PPDN is The structural formula of triaxial compounds is as follows:

[0165] Optionally, the N-type host material of the N-type charge-generating layer N-CGL can be an electronically type material containing phenanthroline or phosphoyl groups, for example... The second dopant can be an alkali metal or its compound such as lithium (Li), ytterbium (Yb), sodium (Na), potassium (K) or cesium (Cs), or an alkali metal or its compound such as magnesium (Mg), strontium (Sr), barium (Ba) or radium (Ra), or an alkaline earth metal or its oxide, or a transition metal or its compound, etc.

[0166] Optionally, the material of the electron injection layer (EIL) can be an alkali metal or a metal, such as LiF, Yb, Mg, Ca and their respective compounds.

[0167] In some embodiments, such as Figure 3 As shown, the thickness range of each organic functional layer can also be represented by the following examples.

[0168] Optionally, the following layers are included: 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 (20-60 nm) for red light-emitting device R, first electron blocking layer GEBL1 (5-30 nm) for green light-emitting device G, first electron blocking layer BEBL1 (5-15 nm) for blue light-emitting device B, first emitting layer REML1 (20-60 nm) for red light-emitting device R, first emitting layer GEML1 (20-50 nm) for green light-emitting device G, first emitting layer BEML1 (10-40 nm) for blue light-emitting device B, first hole blocking layer HBL1 (5-15 nm), first electron transport layer ETL1 (10-40 nm), and N-type charge generation layer N-CGL (15-25 nm). m), P-type charge generation layer P-CGL (5-15nm), second hole transport layer HTL2 (5-70nm), second electron blocking layer REBL2 (5-45nm) for red light-emitting device R, second electron blocking layer GEBL2 (10-25nm) for green light-emitting device G, second electron blocking layer BEBL2 (5-15nm) for blue light-emitting device B, second emitting layer REML2 (30-80nm) for red light-emitting device R, second emitting layer GEML2 (20-50nm) for green light-emitting device G, second emitting layer BEML2 (10-40nm) for blue light-emitting device B, second hole blocking layer HBL2 (5-15nm), second electron transport layer ETL2 (20-100nm), electron injection layer EIL (1-15nm), cathode 2 (10-20nm).

[0169] The following example illustrates the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B used in the embodiments and comparative examples of this disclosure.

[0170] The materials used in each light-emitting device are as follows: the anode 1 is made of indium tin oxide (ITO); the hole injection layer HIL is made of... The first hole transport layer HTL1 and the second hole transport layer HTL2 are made of the same material. Material selection for the first electron blocking layer EBL1 of the red light-emitting device R The material of the second electron blocking layer EBL2 of the red light-emitting device R is a material doped with 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 based on the material of the first electron blocking layer EBL1 of the green light-emitting device G, but doped with exciton dopant. 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 based on the material of the first electron blocking layer EBL1 of the blue light-emitting device B, but doped with exciton dopant. The red host material RH is an exciton complex, which includes p-type materials. and N-type materials The red object material RD is The green host material GH is an excimer compound, which includes p-type materials. and N-type materials Green object material GD is The blue main material is BH. Blue object material BD is The first hole-blocking layer HBL1 and the second hole-blocking layer HBL2 are made of the same material. The first electron transport layer ETL1 and the second electron transport layer ETL2 are made of the same material. The N-type host material of the N-type charge generation layer N-CGL is The second doping material is metallic Yb. The P-type host material of the P-type charge generation layer P-CGL is... The first doped material is The electron injection layer (EIL) is made of metallic Yb. The cathode 2 is made of MgAg (doping ratio 1:9). It should be noted that, unless otherwise specified in this disclosure, the materials used in the "comparative examples" below are the same as those given in this paragraph.

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

[0172] Taking the above relationship (I) 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 (first thickness) and the sum of the thickness of the second light-emitting layer EML2 and the thickness of the second electron blocking layer EBL2 (second thickness) is used to determine the performance (including voltage, efficiency and lifetime) of each light-emitting device through different simulation results.

[0173] Comparative Example 1 0.5 101％ 88％ 90％ Comparative Example 2 1.3 102％ 95％ 83％ Example 3 1 100％ 100％ 100％

[0174] Comparative Example 1 0.7 103％ 83％ 94％ Comparative Example 2 1.25 102％ 96％ 86％ Example 3 1 100％ 100％ 100％

[0175] Comparative Example 1 0.6 100％ 85％ 79％ Comparative Example 2 1.4 99％ 89％ 87％ Example 3 1 100％ 100％ 100％

[0176] The comparison results of the above comparative examples and embodiments show that, by adjusting L1 / L2 and optimizing the light emission position, the present embodiment further improves the superposition effect of the upper and lower light emission layers EML while ensuring that the light emission layer EML is located near the antinode (microcavity reinforcement region).

[0177] Taking the above relationship (iii) as an example, the distance between the third surface of the first light-emitting layer EML1 near the anode 1 and the first surface is the ratio of the first distance L3 to the microcavity length L, L3 / L. The performance of each light-emitting device (including voltage, efficiency and lifetime) is determined by different simulation results.

[0178] Comparative Example 1 0.1 103％ 88％ 92％ Comparative Example 2 0.5 102％ 90％ 87％ Example 3 0.24 100％ 100％ 100％

[0179] Comparative Example 1 0.08 103％ 94％ 88％ Comparative Example 2 0.4 102％ 89％ 86％ Example 3 0.18 100％ 100％ 100％

[0180] Comparative Example 1 0.05 102％ 91％ 91％ Comparative Example 2 0.35 103％ 86％ 93％ Example 3 0.21 100％ 100％ 100％

[0181] The comparison results of the above comparative examples and embodiments show that the embodiments of this disclosure optimize L3 / L by adjusting the first light-emitting layer EML1 of the tandem OLED device to the vicinity of the antinode of the resonant microcavity (microcavity reinforcement region), thereby improving the light extraction efficiency of the tandem OLED device.

[0182] Taking the above relationship (iv) as an example, the distance between the fourth surface of the second light-emitting layer EML2 near the anode 1 and the first surface is the ratio of the second distance L4 to the microcavity length L, L4 / L. The performance of each light-emitting device (including voltage, efficiency and lifetime) is determined by different simulation results.

[0183] Comparative Example 1 0.4 103％ 86％ 97％ Comparative Example 2 0.8 101％ 82％ 96％ Example 3 0.6 100％ 100％ 100％

[0184] Comparative Example 1 0.5 102％ 90％ 92％ Comparative Example 2 0.85 100％ 82％ 91％ Example 3 0.66 100％ 100％ 100％

[0185] Comparative Example 1 0.5 101％ 90％ 93％ Comparative Example 2 0.9 103％ 95％ 91％ Example 3 0.71 100％ 100％ 100％

[0186] The comparison results of the above comparative examples and embodiments show that the embodiments of this disclosure optimize L4 / L by adjusting the second light-emitting layer EML2 of the tandem OLED device to the vicinity of the antinode of the resonant microcavity (microcavity reinforcement region), thereby improving the light extraction efficiency of the tandem OLED device.

[0187] Taking the above relationship (5) as an example, the ratio of the third thickness L5 of the charge generation separation unit 4 to the microcavity length L, L5 / L, is used to determine the performance (including voltage, efficiency and lifetime) of each light-emitting device through different simulation results.

[0188] Comparative Example 1 0.05 103％ 96％ 82％ Comparative Example 2 0.15 98％ 89％ 95％ Example 3 0.09 100％ 100％ 100％

[0189] Comparative Example 1 0.05 102％ 92％ 85％ Comparative Example 2 0.2 100％ 89％ 94％ Example 3 0.12 100％ 100％ 100％

[0190] Comparative Example 1 0.05 104％ 93％ 89％ Comparative Example 2 0.2 103％ 95％ 91％ Example 3 0.15 100％ 100％ 100％

[0191] The comparison results of the above comparative examples and embodiments show that the optimized L5 / L of the embodiments disclosed in this disclosure can improve the crosstalk phenomenon between different pixels, reduce the voltage of the device, and ensure that the series OLED has relatively low power consumption.

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

[0193] Comparative Example 1 EML1 > EML2 99％ 96％ 82％ Example 2 EML1 < EML2 100％ 100％ 100％

[0194] Simulation experiments have verified that the second emitting layer EML2 has a significant impact on the lifetime of red OLED devices. Increasing the thickness of the second emitting layer EML2 helps to widen the exciton recombination region and move it toward the center of the second emitting layer EML2, thereby improving the device lifetime.

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

[0196] Comparative Example 1 Undoped EBL1 > EBL2 102％ 82％ 85％ Example Doped EBL1 < EBL2 100％ 100％ 100％

[0197] Simulation experiments have verified that the exciton trapping agent doped in the second electron blocking layer EBL2 can ensure a good trapping effect and effectively trap holes injected into the second electron blocking layer EBL2. Furthermore, the thickness of the second electron blocking layer EBL2 is greater than that of the first electron blocking layer EBL1, which allows 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. This reduces the exciton utilization rate and consequently leads to a significant decrease in the device's lifetime and efficiency.

[0198] For red light-emitting devices R, the material of the electron blocking layer EBL is further improved by doping with exciton traps.

[0199] 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] Simulation experiments have verified that by optimizing the doping concentration of exciton trapper in the electron blocking layer (EBL) material, the lifetime and efficiency of the light-emitting device can be balanced.

[0201] For example, in conjunction with the above material examples, the possible embodiments of the red light-emitting device R and their device effects are shown in Table 1 below.

[0202] Table 1

[0203]

[0204]

[0205] For example, in conjunction with the above material examples, the possible embodiments of the green light-emitting device G and their device effects are shown in Table 2 below.

[0206] Table 2

[0207]

[0208]

[0209] For example, in conjunction with the above material examples, the possible embodiments of the blue light-emitting device B and their device effects are shown in Table 3 below.

[0210] Table 3

[0211]

[0212]

[0213] The above is a complete description of the light-emitting device provided in the embodiments of this disclosure.

[0214] In addition, this disclosure also provides a display panel that includes light-emitting devices of any of the above embodiments and combinations thereof.

[0215] Specifically, Figure 6 This is a schematic diagram of multiple light-emitting devices in a display panel provided in an embodiment of this disclosure, such as... Figure 6 As shown, the display panel includes a substrate and a plurality of light-emitting devices disposed on the substrate. Each 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 includes at least a first light-emitting unit 31 and a second light-emitting unit 32, with the first light-emitting unit 31 being closer to the anode 1 than the second light-emitting unit 32. This disclosure uses two light-emitting units as an example, with the charge generation separation unit 4 located between the first light-emitting unit 31 and the second light-emitting unit 32. The plurality of light-emitting devices includes, 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 further includes a partition structure disposed between two adjacent light-emitting devices; wherein the two light-emitting devices emit light of different colors, and the charge generation separation unit 4 of the two light-emitting devices is isolated at the position of each partition structure, thereby blocking the lateral flow of charge and improving color crosstalk between different light-emitting devices.

[0217] Optionally, the charge generation separation unit 4 of each light-emitting device is integrated into a single structure.

[0218] In one possible implementation, Figure 7 This is a schematic diagram of the partition structure in Example 1 of the display panel provided in the embodiments of this disclosure, as shown below. Figure 7 As shown, the display panel also includes a pixel defining layer (PDL) and a support layer (02) disposed on the side of the pixel defining layer (PDL) facing away from the substrate 01. The pixel defining layer (PDL) includes pixel openings (V) corresponding to each light-emitting device and barrier structures forming the pixel openings (V). The support layer (02) includes a support portion (021) located on the barrier structure, which 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 concave, which can be used to partition the charge generation separation unit (4) located on the upper layer, thereby improving color crosstalk between different light-emitting devices.

[0219] For example, the support 021 includes an upper surface and a lower surface disposed 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°, so as to avoid the tilt angle being too large or too large to play a blocking role, and also to avoid excessive blocking causing discontinuity of the cathode 2.

[0220] For example, the thickness H1 of the support 021 is between 0.8 and 2 μm to avoid it being too high to provide a shielding effect, and too low to provide a partition effect.

[0221] In another possible implementation, Figure 8 This is a schematic diagram of the partition structure in Example 2 of the display panel provided in the embodiments of this disclosure, as shown below. Figure 8 As shown, the display panel also includes a pixel defining layer (PDL) and a support layer (02) disposed on the side of the pixel defining layer (PDL) facing away from the substrate 01. The pixel defining layer (PDL) includes pixel openings (V) corresponding to each light-emitting device, transition openings (V0) located between two adjacent light-emitting devices, and barrier structures forming the pixel openings (V) and transition openings (V0). The support layer (02) includes a support portion (021) located on the barrier structure, which is consistent with the above-mentioned... Figure 7 The difference in the implementation method is that the support part 021 is not a partition structure, the longitudinal section of the support part 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 also includes a passivation layer PVX disposed on the side of the pixel defining layer PDL near the substrate 01, a planarization layer PLN disposed on the side of the passivation layer PVX near the substrate 01, and a driving layer 0341 disposed on the side of the planarization layer PLN near the substrate 01. The driving layer includes pixel driving circuits (not shown in the figure) for driving each light-emitting device. 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 a first opening 41 corresponding to the transition opening V0, and the planarization layer PLN includes a second opening 42 corresponding to the first opening 41. The opening size of the first opening 41 is smaller than the opening size of the second opening 42, with a difference between them between 0.1 and 1 μm. Thus, a discontinuity is formed between the first opening 41 and the second opening 42, thereby creating a barrier structure that can isolate the charge generation separation unit 4, thereby improving color crosstalk between different light-emitting devices.

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

[0225] In another possible implementation, Figure 9This is a schematic diagram of the partition structure in Example 3 of the display panel provided in the embodiments of this disclosure, as shown below. Figure 9 As shown, the display panel also includes a pixel limiting layer (PDL), which includes pixel openings V corresponding to each light-emitting device and barrier structures forming the pixel openings V.

[0226] The pixel-defining layer (PDL) may have multiple layers, such as two or three layers. This disclosure uses a three-layer PDL as an example for illustration. Figure 10 for Figure 9 Enlarged view of the central partition structure, as shown Figure 10 As shown, the barrier structure of the pixel limiting layer PDL includes a first sublayer 51, a second sublayer 52, and a third sublayer 53 arranged sequentially along the direction away from the substrate 01. The first sublayer 51 protrudes from the side of the pixel opening V defined by it, which is the same as the side of the second sublayer 52 defined by it. The third sublayer 53 protrudes from the side of the second sublayer 52 defined by it, thus forming a gap between the third sublayer 53 and the second sublayer 52, thereby forming a barrier structure that can isolate the charge generation separation unit 4, thereby improving color crosstalk between different light-emitting devices.

[0227] For example, the thickness of the first sublayer 51 is between 0.01 and 0.05 μm. The thickness of the second sublayer 52 is between 0.05 and 0.12 μm. The thickness of the third sublayer 53 is between 0.01 and 0.05 μm. The shortest length of the first sublayer 51 protruding from the second sublayer 52 is between 0.2 and 1 μm, and can be optionally between 0.3 and 0.5 μm. The angle γ between the sidewall of the second sublayer 52 near the pixel opening V and the horizontal surface of the third sublayer 53 near the second sublayer 52 is between 50° and 90°.

[0228] For example, the materials of the first sublayer 51, the second sublayer 52, and the third sublayer 53 can be inorganic, organic, and inorganic stacked materials, or multilayer inorganic stacked materials, such as silicon dioxide (SiO2), silicon oxynitride (SiNx), and silicon dioxide (SiO2) stacked materials. The fabrication process of the pixel-defined layer (PDL) three-layer structure includes: firstly, the first sublayer 51, the second sublayer 52, and the third sublayer 53 are sequentially vapor-deposited across the entire surface; then, photoresist is coated and exposed and developed to expose the area to be etched, and the second sublayer 52 and the third sublayer 53 within the area to be etched are etched once to form the third sublayer 53; then, the second sublayer 52 is etched a second time to form a concave surface, and the second sublayer 52 is obtained; then, the first sublayer 51 is etched a third time to form the first sublayer 51; finally, the photoresist is removed to obtain a barrier structure with isolation capabilities.

[0229] In some embodiments, such as Figure 6 As shown, the distance between the third surface of the first light-emitting layer EML1 near the anode 1 and the first surface 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; or, 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; or, 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 easier understanding, please also refer to the above relationship (III).

[0230] It should be noted that while improving the optical effect of the light-emitting devices, there are relatively strict requirements for the isolation process. For example, the distance from the first light-emitting layer EML1 to the anode 1 is different for the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B. If the isolation structure is too high or too deep, it will cause the cathode 2 to break. If the isolation structure is too low or too shallow, it will not be able to achieve the effect of isolating the charge generation separation unit 4. Therefore, the display panel disclosed in this invention simplifies the isolation process limitations of the isolation structure by adjusting the first distance L3 between the first light-emitting layer EML1 and the anode 1. At the same time, it ensures that the first light-emitting layer EML1 of each light-emitting device is set at the first antinode of the resonant wave of the resonant microcavity, and the second light-emitting layer EML2 is set at the second antinode of the resonant wave of the resonant microcavity, thus ensuring the device effect.

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

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

[0233] Optionally, the encapsulation layer can be a single-layer or multi-layer encapsulation structure, such as a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer sequentially arranged along the direction away from the substrate 01. The first inorganic encapsulation layer includes one or more inorganic layers (each layer has a different refractive index), the organic encapsulation layer includes one or more organic layers and has a planarization function, and the second inorganic encapsulation layer includes one or more inorganic layers.

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

[0235] The organic encapsulation layer can alleviate internal stress in the first inorganic encapsulation layer and / or the second inorganic encapsulation layer. The organic encapsulation layer may include polymeric materials. Polymeric 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 the side of the encapsulation layer opposite to the substrate 01.

[0237] For example, the display panel is a flexible display panel. To realize the touch function of the flexible display panel, a flexible touch panel can be made using the Flexible Multiple Layer On Cell (F-MLOC) process, wherein the touch layer is disposed between the thin film encapsulation layer and the black matrix of the flexible touch panel, thus creating a flexible touch panel with touch function.

[0238] In some embodiments, the display panel further includes a color filter layer disposed on the side of the touch layer facing away from the substrate 01. The color filter layer includes color filters corresponding to the light-emitting devices, 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, a black matrix is ​​present between adjacent color filters. This black matrix can be formed by stacking multiple layers of color filters, or it can be formed using a black matrix material.

[0240] This disclosure also provides a method for fabricating the light-emitting device in the above-mentioned display panel, specifically including steps S11 to S116.

[0241] S11. The glass plate (substrate 01) with the anode 1ITO is ultrasonically treated in a cleaning agent, rinsed in deionized water, ultrasonically degreased in an acetone-ethanol mixed solvent, and baked in a clean environment until all moisture is removed.

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

[0243] S13. Hole transport material is deposited on the hole injection layer HIL to form the first hole transport layer HTL1.

[0244] S14. On the first hole transport layer HTL1, a first electron blocking material is deposited by vapor deposition to form a first electron blocking layer EBL1.

[0245] S15. Evaporate luminescent material onto the first electron blocking layer EBL1 to form the first luminescent layer EML1.

[0246] S16. Hole blocking material is vacuum-deposited on the first light-emitting layer EML1 to form the first hole blocking layer HBL1.

[0247] S17. Vacuum evaporation of electron transport material on the first hole blocking layer HBL1 to form the first electron transport layer ETL1.

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

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

[0250] S10. Hole transport material is deposited on the P-type charge generation layer P-CGL to form the second hole transport layer HTL2.

[0251] S111, a second electron blocking material is deposited on the second hole transport layer HTL2 to form the second electron blocking layer EBL2.

[0252] S112. Evaporate luminescent material onto the second electron blocking layer EBL2 to form the second luminescent layer EML2.

[0253] S113. Hole blocking material is vacuum-deposited on the second light-emitting layer EML2 to form the second hole blocking layer HBL2.

[0254] S114. Vacuum evaporation of electron transport material onto the second hole blocking layer HBL2 to form the second electron transport layer ETL2.

[0255] S115. Vacuum evaporation of electron injection material (1 nm thick, Yb material) onto the second electron transport layer ETL2 to form the electron injection layer EIL.

[0256] S116. A MgAg (1:9) layer is deposited on the electron injection layer EIL as the cathode 2 of the device.

[0257] This disclosure also provides a display device, which includes the display panel of any of the above embodiments. The display device can be, for example, any product with a display function such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or in-vehicle device. Other essential components of this display device are those that should be understood by those skilled in the art, and will not be described in detail here, nor should they be construed as limiting this disclosure.

[0258] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this 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 includes a plurality of antinodes; the charge generation and separation unit includes an N-type charge generation layer and a P-type charge generation layer sequentially disposed along the direction from the anode to the cathode; The plurality of light-emitting units include at least a first light-emitting unit and a second light-emitting unit, wherein 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 disposed on the side of the first light-emitting layer near the anode; the second light-emitting unit includes a second light-emitting layer and a second electron blocking layer disposed on the side of the second light-emitting layer near the anode; The first light-emitting layer is disposed at the first antinode of the resonant wave of the resonant microcavity; the second light-emitting layer is disposed at the second antinode of the resonant wave of the resonant microcavity. 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 includes a red light-emitting device, and the ratio of the first thickness to the second thickness is between 0.6 and 1.2; The light-emitting device includes a red light-emitting device. The thickness of the first electron blocking layer is greater than the thickness of the second electron blocking layer. The material of the second electron blocking layer is doped with an exciton trapping agent. The HOMO energy level of the exciton trapping agent is shallower than the HOMO energy level of the second electron blocking layer. The doping concentration of the exciton trapping agent is between 0.5% and 2%. The doping concentration of the exciton trapping agent refers to the ratio of the mass of the exciton trapping agent to the mass of the material of the second electron blocking layer. The exciton trapping agent can trap some holes in the second electron blocking layer.

2. The light-emitting device according to claim 1, wherein, The light-emitting device includes 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 includes a blue light-emitting device, and the ratio of the first thickness to the second thickness is between 0.8 and 1.

2.

3. The light-emitting device according to claim 1, wherein, The distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; the distance between the third surface of the first light-emitting layer near the anode and the first surface is the first distance; The light-emitting device includes 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 includes a green light-emitting device, and the ratio of the thickness of the first distance to the length of the microcavity is between 0.1 and 0.3; or, the light-emitting device includes a blue light-emitting device, and the ratio of the thickness of the first distance to the length of the microcavity is between 0.1 and 0.

3.

4. The light-emitting device according to claim 1, wherein, The distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the cavity length of the resonant microcavity; the distance between the fourth surface of the second light-emitting layer near the anode and the first surface is the second distance; The light-emitting device includes 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 includes a green light-emitting device, and the ratio of the thickness of the second distance to the length of the microcavity is between 0.55 and 0.75; or, the light-emitting device includes a blue light-emitting device, and the ratio of the thickness of the second distance to the length of the microcavity is between 0.6 and 0.

8.

5. The light-emitting device according to claim 1, wherein, The distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; The thickness of the charge generation separation unit is denoted as the third thickness; The light-emitting device includes 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 includes 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 includes 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.

6. The light-emitting device according to claim 1, wherein, The absolute value of the difference between the HOMO energy level of the exciton trapper and the HOMO energy level of the second electron blocking layer is greater than or equal to 0.2 eV.

7. The light-emitting device according to claim 1, wherein, The general structural formula (I) of the materials used in the exciton trapping agent is as follows: ； In this context, Ra and Rb are each independently represented as substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl; Rc, Rd, Re and Rf are each independently represented as substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

8. The light-emitting device according to claim 7, wherein, The structure of the exciton trapping agent includes any of the following: ； ； ； ； ； ； ； ； ； ； ； 。 9. The light-emitting device according to claim 1, wherein, The material of the exciton trapping agent is the same as the red guest material of the second luminescent layer.

10. The light-emitting device according to claim 1, wherein, The light-emitting device is a color-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.

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

12. The light-emitting device according to claim 10, wherein, The material of the first light-emitting layer is different from that of the second light-emitting layer; the hole mobility of the second light-emitting layer is greater than that of the first light-emitting layer.

13. The light-emitting device according to claim 1, wherein, 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 the side of the hole injection layer near the first electron blocking layer, a first hole blocking layer disposed on the side of the first light-emitting layer near the N-type charge generation layer, and a first electron transport layer disposed on the side of the first hole blocking layer near the N-type charge generation layer. The second light-emitting unit further includes an electron injection layer, a second electron transport layer, and a second hole blocking layer sequentially disposed 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 generating layer.

14. The light-emitting device according to claim 13, 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 is in the range of 0.1 eV to 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 is in the range of 0.1 eV to 0.4 eV.

15. The light-emitting device according to claim 13, wherein, The material of the first hole transport layer is different from that of the second hole transport layer; the hole mobility of the first hole transport layer is greater than that of the second hole transport layer.

16. The light-emitting device according to claim 13, wherein, The material of the P-type charge generation layer includes a P-type host material and a first dopant; the first dopant is a material represented by structural formula (ii) or structural formula (iii); The general structural formula (II) is as follows: ； Wherein, A1-A6 each independently represent a substituted or unsubstituted halogen, a substituted or unsubstituted cyano, a substituted or unsubstituted aryl, or a substituted or unsubstituted heteroaryl; when each of A1-A6 independently represents an aryl substituent, the aryl group may be substituted by an electron-withdrawing group; A represents 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: ； In this context, X1 and X2 are each independently represented by one of C, N, or Si; Y1 and Y2 are each independently represented by one of O, N, or S; Ar1-Ar4 are each independently represented by 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 are each independently represented by 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, or a substituted or unsubstituted aryl group. Alkyl groups with 1 to 5 carbon atoms (substituted or unsubstituted), haloalkyl groups with 1 to 10 carbon atoms (substituted or unsubstituted), cycloalkyl groups with 3 to 10 carbon atoms (substituted or unsubstituted), heterocycloalkyl groups with 2 to 10 carbon atoms (substituted or unsubstituted), alkoxy groups with 1 to 10 carbon atoms (substituted or unsubstituted), alkylthio groups with 1 to 10 carbon atoms (substituted or unsubstituted), aryloxy groups with 6 to 18 carbon atoms (substituted or unsubstituted), arylthio groups with 6 to 18 carbon atoms (substituted or unsubstituted), phosphoroxy groups with 6 to 24 carbon atoms (substituted or unsubstituted), and alkylsulfonyl groups with 6 to 18 carbon atoms (substituted or unsubstituted); a and b are each independently represented as integers from 1 to 5.

17. The light-emitting device according to claim 13, wherein, The N-type host material of the N-type charge generation layer is a material represented by the general structural formula (iv); The general structural formula (four) is as follows: ； In this context, X1-X4 are each independently represented as N or C(R1), and each of X1-X4 independently contains at least two N atoms; R1 is selected from hydrogen, deuterium, substituted or unsubstituted C1 atoms. 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 heterocyclic alkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocyclic alkenyl, 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 heterocyclic group; Ar1, Ar2 Ar3 and Ar4 may be the same or different, and each is independently represented as selected from one of 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.

18. The light-emitting device according to any one of claims 1 to 17, wherein, The distance between the first surface of the anode near the cathode and the second surface of the cathode near the anode is the microcavity length of the resonant microcavity; The light-emitting device includes a red light-emitting device, and the microcavity length ranges from 2500 angstroms to 3000 angstroms; or, the light-emitting device includes a green light-emitting device, and the microcavity length ranges from 2500 angstroms to 2600 angstroms; or, the light-emitting device includes a blue light-emitting device, and the microcavity length ranges from 1500 angstroms to 2000 angstroms.

19. 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 excimer complex.

20. The light-emitting device according to claim 13, wherein, The light-emitting device includes 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 host material of the first luminescent layer; The triplet energy level of the first electron blocking layer is greater than the triplet energy level of the blue host material of the first luminescent layer.

21. A display panel, wherein, Includes the light-emitting device as described in any one of claims 1 to 20.

22. The display panel according to claim 21, wherein, The display panel also 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 unit of the two light-emitting devices is separated at the location of the partition structure.

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