Light-emitting device, display panel and display device

Abstract

The embodiment of the invention provides a light-emitting device, a display panel and a display device, relates to the technical field of display, and aims to solve the problem of trailing or ghosting. The light emitting device includes a first electrode, a second electrode, and at least two light emitting units. The first electrode and the second electrode are stacked in the first direction. The at least two light-emitting units are arranged between the first electrode and the second electrode and arranged in the second direction, and the second direction intersects with the first direction. Photons emitted by each of the at least two light-emitting units comprise a first type of light-emitting photons and a second type of light-emitting photons, and the emission time of the first type of light-emitting photons is shorter than the emission time of the second type of light-emitting photons. Wherein in the at least two light-emitting units, the number of the second type of light-emitting photons of at least one light-emitting unit is smaller than or equal to the number of the first type of light-emitting photons. The light-emitting device is used for displaying images.

Description

Light-emitting device, display panel, and display apparatus Technical Field

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

[0002] Organic Light Emitting Diode (OLED) display devices have the advantages of self-luminescence, high color gamut, high saturation, and high response speed, and are widely used in display screens such as mobile phones, tablets, and car displays.

[0003] Summary of the Invention

[0004] In one aspect, a light-emitting device is provided. The light-emitting device includes a first electrode, a second electrode, and at least two light-emitting units. The first electrode and the second electrode are stacked along a first direction. At least two light-emitting units are disposed between the first electrode and the second electrode and arranged along a second direction, wherein the second direction intersects with the first direction. The photons emitted by each of the at least two light-emitting units include: a first type of light-emitting photons and a second type of light-emitting photons, wherein the emission time of the first type of light-emitting photons is less than the emission time of the second type of light-emitting photons. The number of the second type of light-emitting photons emitted by at least one light-emitting unit is less than or equal to the number of the first type of light-emitting photons.

[0005] In some embodiments, the at least two light-emitting units include at least three light-emitting units, and the at least three light-emitting units are arranged along the second direction; under normalized conditions, between any two light-emitting units, the difference between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting units is less than or equal to 40%.

[0006] In some embodiments, each of the at least two light-emitting units includes at least one light-emitting layer; each of the at least one light-emitting layer includes: a first host material and a light-emitting material; and at least one light-emitting layer further includes a second host material. The triplet energy level of the second host material is less than or equal to the triplet energy level of the first host material; and the triplet energy level of the second host material is greater than or equal to the triplet energy level of the light-emitting material.

[0007] In other embodiments, the difference between the triplet energy level of the first host material and the triplet energy level of the second host material is greater than or equal to 0.1 eV; the difference between the triplet energy level of the second host material and the triplet energy level of the light-emitting material is greater than or equal to 0.1 eV.

[0008] In some further embodiments, the difference between the peak wavelength of the emission spectrum of the second host material and the peak wavelength of the absorption spectrum of the luminescent material is less than or equal to 40 nm.

[0009] In some further embodiments, the difference between the peak wavelength of the emission spectrum of the second host material and the peak wavelength of the absorption spectrum of the luminescent material is less than or equal to 30 nm.

[0010] In some further embodiments, the singlet energy level of the first host material is greater than or equal to the singlet energy level of the second host material; and the singlet energy level of the second host material is greater than or equal to the singlet energy level of the light-emitting material.

[0011] In yet other embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level of the second host material and the highest occupied molecular orbital energy level of the first host material is less than or equal to 0.3 eV. The absolute value of the difference between the lowest occupied molecular orbital energy level of the second host material and the lowest occupied molecular orbital energy level of the luminescent material is less than or equal to 0.2 eV. The absolute value of the lowest occupied molecular orbital energy level of the second host material is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level of the first host material. The absolute value of the lowest occupied molecular orbital energy level of the luminescent material is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level of the first host material.

[0012] In some further embodiments, in each light-emitting layer, a difference between a triplet energy level of the first host material and a triplet energy level of the light-emitting material is greater than or equal to 0.15 eV.

[0013] In some further embodiments, the second host material includes any one of the ligand groups IA shown in Formula I.

[0014] wherein F is selected from a five-membered or six-membered carbocyclic or carbon heterocyclic ring; the value of m is selected from any one of 0, 1, 2, 3 and 4; Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen; the ligand group IA is connected to M, and M is selected from any one of ruthenium, osmium, iridium, palladium, copper, silver and gold; the second host material includes an n-dentate ligand material formed by M as shown in the general formula I, and the value of n is selected from any one of 3, 4, 5 and 6; Ra, Rb and Rc are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thio, sulfinyl, sulfonyl and phosphino.

[0015] In some further embodiments, the second host material is selected from any one of the structures shown in the following general formula II.

[0016] wherein F is selected from a five-membered or six-membered carbocyclic ring or carboheterocyclic ring; m is selected from any one of 0, 1, 2, 3 and 4; J and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or carboheterocyclic ring; Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen; M is selected from one of platinum and palladium; L1 and L2 are the same or different and are independently selected from B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf wherein R, Rb, Rc, Re, Rd, Rf and Rg are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl and phosphino.

[0017] In yet other embodiments, J and E are not both five-membered carbocyclic or carboheterocyclic rings.

[0018] In still other embodiments, L1 and L2 are different.

[0019] In yet other embodiments, at least one of Ra, Rb, and Rc contains deuterium.

[0020] In some other embodiments, the mass proportion of the second host material in the light-emitting layer is greater than or equal to 10% and less than or equal to 50%.

[0021] In some further embodiments, the second host material is selected from any one of the structures shown in the following general formulas I and II.

[0022] wherein X1 and X2 are the same or different and are independently selected from one of carbon and nitrogen; R1, R2, R3 and R4 are the same or different and are independently selected from one of a substituted or unsubstituted substituent group IIIA and a substituted or unsubstituted substituent group IIIB; and among R1, R2, R3 and R4, there are at least two substituted or unsubstituted substituent groups IIIA and at least one substituted or unsubstituted substituent group IIIB; and the substituent group IIIA is selected from any one of IIIA-a to IIIA-i.

[0023] wherein Z is selected from any one of carbon, nitrogen, oxygen and sulfur; and Rh is selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl and phosphino.

[0024] The substituent group IIIB is selected from any one of IIIB-a to IIIB-j.

[0025] wherein X3 is selected from one of oxygen and sulfur; and Rj is selected from any one of hydrogen, deuterium, halogen, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted haloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted haloalkoxy, substituted or unsubstituted aryl, substituted or unsubstituted haloaryl, substituted or unsubstituted silyl and substituted or unsubstituted heterocycle.

[0026] In some other embodiments, the mass ratio of the second host material in the light-emitting layer is greater than or equal to 20% and less than or equal to 55%.

[0027] In some other embodiments, the mass ratio of the second host material in the light-emitting layer is less than or equal to the mass ratio of the first host material in the light-emitting layer.

[0028] In some further embodiments, the light-emitting unit includes a plurality of light-emitting layers, and the plurality of light-emitting layers are stacked along the first direction.

[0029] In another aspect, a display panel is provided, comprising: a light-emitting device as described in any one of the above embodiments and a driving circuit, wherein the driving circuit is configured to drive the light-emitting device to emit light.

[0030] In another aspect, a display device is provided. The display device comprises the display panel and a driver chip according to any of the above embodiments. The driver chip is used to drive the display panel to display. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the technical solutions of the present disclosure, the following briefly introduces the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure, and those skilled in the art can also derive other drawings based on these drawings. Furthermore, the drawings described below are schematic diagrams and are not intended to limit the actual dimensions of the products, actual processes of the methods, actual timing of signals, and the like involved in the embodiments of the present disclosure.

[0032] FIG1 is a structural diagram of a display device according to some embodiments of the present disclosure;

[0033] FIG2 is a structural diagram of a display panel provided according to some embodiments of the present disclosure;

[0034] FIG3 is a structural diagram of a light emitting device provided according to some embodiments of the present disclosure;

[0035] FIG4 is another structural diagram of a light emitting device according to some embodiments of the present disclosure;

[0036] FIG5 is another structural diagram of a light emitting device according to some embodiments of the present disclosure;

[0037] FIG6 is a transient decay curve diagram of a light emitting device provided by some embodiments of the present disclosure;

[0038] FIG7 is another transient decay curve diagram of the light emitting device provided by some embodiments of the present disclosure;

[0039] FIG8 is another transient decay curve diagram of the light emitting device provided by some embodiments of the present disclosure;

[0040] FIG9 is another transient decay curve diagram of the light emitting device provided by some embodiments of the present disclosure;

[0041] FIG10 is another transient decay curve diagram of the light emitting device provided by some embodiments of the present disclosure. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0043] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0044] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0045] “At least one of A, B and C” has the same meaning as “at least one of A, B or C” and both include the following combinations of A, B and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B and C.

[0046] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0047] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0048] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within an acceptable deviation range, wherein the acceptable deviation range is as determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism can be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity can also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality can be, for example, that the difference between the two equals is less than or equal to 5% of either one.

[0049] It will be understood that when a layer or element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present therebetween.

[0050] Exemplary embodiments are described herein with reference to cross-sectional and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include deviations in shape due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0051] It should be noted that, for example, 11-1 in the drawings of the present disclosure indicates that component 11 belongs to component 1, and for example, 131-130 indicates that the light-emitting layer 131 belongs to the light-emitting unit 130. Other similar numbers appearing in the drawings also follow the above description.

[0052] Referring to FIG. 1 , some embodiments of the present disclosure provide a display device 300 , which includes a display panel 200 .

[0053] In some examples, the display device 300 may be an OLED (Organic Light Emitting Diode) display device.

[0054] 1 , the display device 300 further includes a driver chip 310. The driver chip 310 is used to drive the display panel 200 to perform display.

[0055] In addition, the display device 300 may also include an under-screen camera and an under-screen fingerprint recognition sensor, so that the display device 300 can realize various functions such as taking pictures, recording videos, fingerprint recognition or face recognition.

[0056] The display device 300 described above can be any display device 300 that displays either motion (e.g., video) or fixed (e.g., still images) and text or images. More specifically, it is contemplated that the display device 300 of the embodiments described herein can be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, video cameras, game consoles, watches, clocks, calculators, television monitors, flat-panel displays, computer monitors, automotive displays (e.g., speedometer displays, etc.), navigation systems, cockpit controls and / or displays, displays of camera views (e.g., displays of rearview cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0057] In some embodiments, referring to FIG. 2 , the display panel 200 includes a display substrate 210 . The display substrate 210 includes an array layer 211 and a light-emitting functional layer 212 . The light-emitting functional layer 212 is located on one side of the array layer 211 . The array layer 211 includes a plurality of driving circuits 2111 . The light-emitting functional layer 212 includes a plurality of light-emitting devices 100 .

[0058] 2 , multiple driving circuits 2111 and multiple light emitting devices 100 may be coupled one-to-one. In other examples, one driving circuit 2111 may be coupled to multiple light emitting devices 100 , or multiple driving circuits 2111 may be coupled to one light emitting device 100 .

[0059] For example, in the display panel 200, the driving circuit 2111 can generate a driving current. Each light-emitting device 100 can emit light under the driving action of the driving current generated by the corresponding driving circuit 2111. The light emitted by multiple light-emitting devices 100 cooperates with each other, thereby enabling the display panel 200 to achieve a display function.

[0060] In some implementations, when an OLED display device displays a certain image for a long time and then switches, problems such as slight trailing or afterimage may occur.

[0061] In other implementations, the display image of an OLED display device is created by mixing red (R), green (G), and blue (B), and the response speeds of the three RGB colors vary. When the response speed differences between the three RGB colors are large, the display image may suffer from trailing or afterimages.

[0062] Based on this, referring to FIG3 , some embodiments of the present disclosure provide a light-emitting device 100, which includes a first electrode 110, a second electrode 120 and at least two light-emitting units 130. The first electrode 110 and the second electrode 120 are stacked along a first direction X. At least two light-emitting units 130 are disposed between the first electrode 110 and the second electrode 120 and arranged along a second direction Y, which intersects with the first direction X. The photons emitted by each of the at least two light-emitting units 130 include: a first type of light-emitting photons and a second type of light-emitting photons, and the emission time of the first type of light-emitting photons is less than the emission time of the second type of light-emitting photons. The number of the second type of light-emitting photons emitted by at least one light-emitting unit 130 is less than or equal to the number of the first type of light-emitting photons.

[0063] In some examples, referring to FIG. 3 , the second direction Y is perpendicular to the first direction X. The first electrode 110 may be an anode, and the second electrode 120 may be a cathode. During operation, a voltage is applied to the first electrode 110 and the second electrode 120, generating an electric field therebetween. This drives the holes in the anode and the electrons in the cathode to recombine in the light-emitting unit 130, thereby emitting light. The emitted light includes light emitted by the first type of luminescent photons and light emitted by the second type of luminescent photons.

[0064] For example, in order to ensure that the light-emitting device 100 can effectively emit light, the first electrode 110 (anode) is made of a material with a high work function, such as a material with a work function greater than 6 eV; the second electrode 120 (cathode) is made of a material with a low work function, such as a material with a work function less than a set value, and the set value can range from 2.0 eV to 3.0 eV. In this way, the holes in the anode and the electrons in the cathode can effectively migrate to the light-emitting unit 130 under the drive of the electric field, thereby compounding and emitting light.

[0065] In some examples, the light-emitting device 100 is a bottom-emitting light-emitting device. The material of the first electrode 110 can be a transparent conductive metal oxide material to prevent the first electrode 110 from blocking light. For example, the material of the first electrode 110 can be indium tin oxide (ITO) or indium zinc oxide (IZO). The thickness of the first electrode 110 can be 80 nm to 200 nm. The average reflectivity of the material of the first electrode 110 in the visible light range can be 85% to 95%. The material of the second electrode 120 can be a metal material. For example, the material of the second electrode 120 can be magnesium, silver, aluminum, or a magnesium-silver alloy. When the material of the second electrode 120 is a magnesium-silver alloy, the mass ratio of magnesium to silver is 3:7 to 1:9. The process of forming the second electrode 120 is, for example, an evaporation process. The thickness of the second electrode 120 can be greater than or equal to 80 nm to ensure good reflectivity.

[0066] In other examples, the light-emitting device 100 is a top-emitting light-emitting device, and the material of the first electrode 110 can be a composite layer structure composed of a metal and a conductive metal oxide. For example, the material of the first electrode 110 can be a composite layer structure composed of silver / indium tin oxide or silver / indium zinc oxide. The thickness of the metal layer can be 80 nm to 100 nm, and the thickness of the conductive metal oxide can be 5 nm to 10 nm. The average reflectivity of the material of the first electrode 110 in the visible light region can be 85% to 95%. The material of the second electrode 120 can be a metal material, for example, magnesium, silver, aluminum, or a magnesium-silver alloy. When the material of the second electrode 120 is a magnesium-silver alloy, the mass ratio of magnesium to silver is 3:7 to 1:9. The process for forming the second electrode 120 is, for example, an evaporation process. The thickness of the second electrode 120 can be 10 nm to 20 nm. The transmittance of the material of the second electrode 120 at 530 nm is 50% to 60%.

[0067] In some embodiments, referring to FIG3 , in order to improve the luminous efficiency of the light-emitting device 100 , at least one of a hole injection layer 140 (HIL), a hole transport layer 150 (HTL), and an electron blocking layer 160 (EBL) is stacked between the first electrode 110 and the light-emitting unit 130 ; and at least one of an electron injection layer 170 (EIL), an electron transport layer 180 (ETL), and a hole blocking layer 190 (EBL) is stacked between the second electrode 120 and the light-emitting unit 130 . By setting up the film layers such as the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the electron injection layer 170, the electron transport layer 180, and the hole blocking layer 190, it is equivalent to setting up transition steps between the anode and the light-emitting unit 130 and between the cathode and the light-emitting unit 130, thereby reducing the potential barrier height that needs to be overcome for carrier transition, thereby making the luminescence efficiency higher.

[0068] Exemplarily, the hole injection layer 140 is configured to reduce the hole injection barrier and improve the hole injection efficiency; the hole injection layer 140 can be a single-layer film formed of a single material, and the material of the hole injection layer 140 is, for example, 11-hexacyano-1 (HAT-CN) or phthalocyanine blue (CuPc); the hole injection layer 140 can also be prepared by P-type doping of the hole transport material, such as doping 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ) in N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), or doping manganese trioxide (MnO3) in 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC); the doping concentration can be 0.5% to 10%. The thickness of the hole injection layer 140 may be 5 nm to 20 nm.

[0069] Exemplarily, the hole transport layer 150 is configured to transport holes. The material of the hole transport layer 150 can be a material with high hole mobility, such as a carbazole material. The hole transport layer 150 can be formed by an evaporation process. The highest occupied molecular orbital (HOMO) energy level of the hole transport layer 150 can be 5.2 eV to 5.6 eV. The thickness of the hole transport layer 150 can be 100 nm to 140 nm.

[0070] For example, the electron blocking layer 160 is configured to block electrons and excitons generated in the light emitting unit 130 ; the thickness of the electron blocking layer 160 may be 1 nm to 10 nm.

[0071] For example, the thickness of the electron injection layer 170 may be 0.5 nm to 2 nm.

[0072] For example, the thickness of the electron transport layer 180 may be 20 nm to 70 nm.

[0073] For example, the hole blocking layer 190 is configured to block holes and excitons generated in the electron transport layer 180 ; the thickness of the hole blocking layer 190 may be 2 nm to 10 nm.

[0074] In some embodiments, referring to FIG3 , the second electrode 120 stacked with each light-emitting unit 130 is a structure that is interconnected throughout the entire layer, meaning that the second electrode 120 can be a common electrode shared by multiple light-emitting units 130. The hole injection layer 140 stacked with each light-emitting unit 130 can also be a structure that is interconnected throughout the entire layer, meaning that the hole injection layer 140 can be a common layer shared by multiple light-emitting units 130. The hole transport layer 150, electron blocking layer 160, hole blocking layer 190, electron injection layer 170, and electron transport layer 180 can also be common layers shared by multiple light-emitting units 130.

[0075] The photons emitted by each of the at least two light-emitting units 130 include: a first type of light-emitting photons and a second type of light-emitting photons, wherein the emission time of the first type of light-emitting photons is shorter than the emission time of the second type of light-emitting photons. It is understandable that the light-emitting unit 130 is the structure in the light-emitting device 100 that realizes the function of emitting light, and the process of emitting light by the light-emitting unit 130 is completed within a light-emitting time period, that is, the emission time corresponding to each photon emitted by the light-emitting unit 130 is different; in this way, among the photons emitted by the light-emitting unit 130, some photons are emitted relatively early, that is, emitted instantaneously; and some photons are emitted relatively late, that is, emitted with a delay; the first type of light-emitting photons are the photons emitted by the light-emitting unit 130 with a relatively early emission time, that is, the first type of light-emitting photons are the instantaneous light-emitting component of the photons emitted by the light-emitting unit 130; the second type of light-emitting photons are the photons emitted by the light-emitting unit 130 with a relatively late emission time, that is, the second type of light-emitting photons are the delayed light-emitting component of the photons emitted by the light-emitting unit 130. For example, the first type of luminous photons are photons with an emission time of less than 1 μs; the second type of luminous photons are photons with an emission time of greater than or equal to 1 μs. It should be noted that the emission time refers to the time from the removal of the driving voltage to the emission of the photon.

[0076] It is understood that, among at least two light-emitting units 130, when the number of second-type light-emitting photons of at least one light-emitting unit 130 is less than or equal to the number of first-type light-emitting photons, the ratio E2 of the number of second-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 is less than or equal to the ratio E1 of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130, that is, E2 ≤ E1. This allows more photons to be emitted quickly under the action of the driving voltage, improving the response speed of the light-emitting unit 130. When a certain image is displayed for a long time and then switched, the trailing and afterimage phenomena of the displayed image can be effectively reduced.

[0077] For example, the ratio E1 of the number of first-type luminous photons to the number of photons emitted by the light-emitting unit 130 and the ratio E2 of the number of second-type luminous photons to the number of photons emitted by the light-emitting unit 130 can be obtained by fitting and calculating the transient decay curve. The transient decay curve can be measured using a transient spectrometer. During the measurement, a square wave signal not less than the driving voltage is input into the light-emitting device 100. The transient spectrometer is, for example, a transient fluorescence spectrometer model FLS1000; the driving voltage is, for example, 3V.

[0078] In some embodiments, the at least two light-emitting units 130 include at least three light-emitting units 130, and the at least three light-emitting units 130 are arranged along the second direction Y; under normalized conditions, between any two light-emitting units 130, the difference between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 is less than or equal to 40%.

[0079] For example, referring to Figures 2 and 3, the at least two light-emitting units 130 include three light-emitting units 130. For example, the three light-emitting units 130 are a red light-emitting unit 130R, a green light-emitting unit 130G, and a blue light-emitting unit 130B. The red light-emitting unit 130R emits red light, the green light-emitting unit 130G emits green light, and the blue light-emitting unit 130B emits blue light. The three light-emitting units 130 are arranged along a second direction Y, which is perpendicular to the first direction X. By configuring the three light-emitting units 130, the brightness (grayscale) of the light-emitting units 130 of different colors can be adjusted separately. By combining and superimposing colors, a multi-color display can be achieved, thereby realizing a full-color display of the display panel 200.

[0080] In other embodiments, the at least two light-emitting units 130 include M light-emitting units 130, where M is a positive integer greater than three, and the M light-emitting units 130 are arranged along the second direction Y, and the second direction Y is perpendicular to the first direction X. For example, the number of red light-emitting units 130R is at least two, and / or the number of green light-emitting units 130G is at least two, and / or the number of blue light-emitting units 130B is at least two.

[0081] It should be noted that the above normalization condition refers to normalizing the number of photons emitted by the light-emitting unit 130 to 1. Under the normalization condition, the number of first-class luminous photons is the ratio of the number of first-class luminous photons to the number of photons emitted by the light-emitting unit 130, and the number of second-class luminous photons is the ratio of the number of second-class luminous photons to the number of photons emitted by the light-emitting unit 130.

[0082] It should be noted that, taking the green light-emitting unit 130G and the red light-emitting unit 130R as an example, the difference between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 between the two light-emitting units 130 means that in the green light-emitting unit 130G, the number of first-type light-emitting photons is G1, and the number of second-type light-emitting photons is G2; in the red light-emitting unit 130R, the number of first-type light-emitting photons is R1, and the number of second-type light-emitting photons is R2; then, between the green light-emitting unit 130G and the red light-emitting unit 130R, the difference ΔGR between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 is:

[0083] When the at least two light-emitting units 130 include a red light-emitting unit 130R, a green light-emitting unit 130G, and a blue light-emitting unit 130B, the difference between the ratio of the number of first-type light-emitting photons to the number of photons emitted by any two of the light-emitting units 130 is less than or equal to 40%, which means that the light-emitting device 100 satisfies the following conditions:

[0084] ΔGR≤40%; ΔBR≤40%; and ΔBG≤40%.

[0085] Among them, the description of the difference ΔBR between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 between the blue light-emitting unit 130B and the red light-emitting unit 130R, and the description of the difference ΔBG between the ratio of the number of first-type light-emitting photons to the number of photons emitted by the light-emitting unit 130 between the blue light-emitting unit 130B and the green light-emitting unit 130G can be found in the above description of ΔGR, and will not be repeated here.

[0086] It can be understood that by limiting the difference between the ratio of the number of first-type luminous photons to the number of photons emitted by the light-emitting units 130 between any two light-emitting units 130, the difference in the ratio of the number of first-type luminous photons to the number of photons emitted by the light-emitting units 130 between each light-emitting unit 130 is reduced, that is, the difference in the ratio of the number of second-type luminous photons to the number of photons emitted by the light-emitting units 130 between each light-emitting unit 130 is reduced, so that the proportion of delayed luminous components in the photons emitted by each light-emitting unit 130 tends to be consistent, and thus the response speed in each light-emitting unit 130 tends to be consistent. When a certain picture is displayed for a long time and then switched, the tailing and afterimage phenomena of the displayed picture can be effectively alleviated.

[0087] Referring to FIG. 4 , in some embodiments, each of the at least two light-emitting units 130 includes at least one light-emitting layer 131 ; each of the at least one light-emitting layer 131 includes a first host material H1 and a light-emitting material D; and the at least one light-emitting layer 131 further includes a second host material H2 . The triplet energy level T1(H2) of the second host material H2 is less than or equal to the triplet energy level T1(H1) of the first host material H1 ; and the triplet energy level T1(H2) of the second host material H2 is greater than or equal to the triplet energy level T1(D) of the light-emitting material D, i.e., T1(D)≤T1(H2)≤T1(H1).

[0088] It can be understood that the light-emitting layer 131 is the part of the light-emitting unit 130 that performs the light-emitting function, and both the first type of light-emitting photons and the second type of light-emitting photons are emitted from the light-emitting layer 131 .

[0089] The light emitting layer 131 includes a first host material H1 and a light emitting material D. Exemplarily, the first host material H1 may be configured to transmit energy; and the light emitting material D may be configured to emit light.

[0090] Illustratively, the structural formula of the first host material H1 may be any one of H1-1 to H1-30 shown below.

[0091] It should be noted that the above-listed structural formulas are examples of the structure of the first host material H1 and are not intended to limit the structure of the first host material H1. H1-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0092] The at least one light-emitting layer 131 further includes a second host material H2, and the triplet energy level T1(H2) of the second host material H2, the triplet energy level T1(H1) of the first host material H1, and the triplet energy level T1(D) of the light-emitting material D satisfy the following conditions: T1(H2)≤T1(H1); T1(H2)≥T1(D).

[0093] The embodiment of the present disclosure adds a second main material H2 to the light-emitting layer 131 and sets the energy transfer direction. That is, since T1(H2)≥T1(D), the second main material H2 can transfer energy to the light-emitting material D. At the same time, since T1(H2)≤T1(H1), the second main material H2 will not transfer energy to the first main material H1, thereby realizing the effective transfer of energy of the second main material H2 to the light-emitting material D.

[0094] In some embodiments, the difference between the triplet energy level T1(H1) of the first host material H1 and the triplet energy level T1(H2) of the second host material H2 is greater than or equal to 0.1eV; the difference between the triplet energy level T1(H2) of the second host material H2 and the triplet energy level T1(D) of the light-emitting material D is greater than or equal to 0.1eV.

[0095] That is, the triplet energy level T1(H1) of the first host material H1, the triplet energy level T1(H2) of the second host material H2, and the triplet energy level T1(D) of the luminescent material D satisfy: T1(H1)-T1(H2)≥0.1eV; T1(H2)-T1(D)≥0.1eV.

[0096] It can be understood that by increasing the difference between the triplet energy level T1(H1) of the first host material H1 and the triplet energy level T1(H2) of the second host material H2, and the difference between the triplet energy level T1(H2) of the second host material H2 and the triplet energy level T1(D) of the luminescent material D, it is further ensured that energy is transmitted in a set direction, that is, the second host material H2 can transmit energy to the luminescent material D, but the second host material H2 will not transmit energy to the first host material H1.

[0097] Illustratively, the difference between the triplet energy level T1(H1) of the first main material H1 and the triplet energy level T1(H2) of the second main material H2 can be 0.1eV, 0.2eV, 0.4eV, 0.6eV or 1eV, etc.; the difference between T1(H2) and T1(D) can be 0.1eV, 0.2eV, 0.3eV, 0.7eV or 1eV, etc.

[0098] In some embodiments, a difference between a peak wavelength of an emission spectrum of the second host material H2 and a peak wavelength of an absorption spectrum of the light-emitting material D is less than or equal to 40 nm.

[0099] It should be noted that the emission spectrum refers to the intensity or energy distribution of light of different wavelengths emitted by the second host material H2 under the excitation of light of a specific wavelength. The absorption spectrum refers to the intensity or energy distribution of light of different wavelengths absorbed by the luminescent material D under the excitation of light of a specific wavelength.

[0100] By setting the difference between the peak wavelength of the emission spectrum of the second main material H2 and the peak wavelength of the absorption spectrum of the luminescent material D to be less than or equal to 40 nm, the energy transfer from the second main material H2 to the luminescent material D can be more sufficient, thereby effectively improving the luminous efficiency of the light-emitting device 100.

[0101] In some embodiments, the difference between the peak wavelength of the emission spectrum of the second host material H2 and the peak wavelength of the absorption spectrum of the luminescent material D is less than or equal to 30 nm. This configuration further enhances the energy transfer effect from the second host material H2 to the luminescent material D, further improving the luminous efficiency of the light-emitting device 100.

[0102] For example, the difference between the peak wavelength of the emission spectrum of the second host material H2 and the peak wavelength of the absorption spectrum of the light-emitting material D may be 30 nm, 25 nm, 21 nm, or 20 nm.

[0103] In some embodiments, the singlet energy level S1(H1) of the first host material H1 is greater than or equal to the singlet energy level S1(H2) of the second host material H2; the singlet energy level S1(H2) of the second host material H2 is greater than or equal to the singlet energy level S1(D) of the light-emitting material D.

[0104] That is, the singlet energy level S1(H1) of the first host material H1, the singlet energy level S1(H2) of the second host material H2, and the singlet energy level S1(D) of the luminescent material D satisfy: S1(H1)≥S1(H2)≥S1(D).

[0105] Through the above arrangement, the direction of energy transmission at the singlet energy level is: the first host material H1 transfers energy to the second host material H2, and the second host material H2 transfers energy to the luminescent material D, thereby improving the luminous efficiency of the light-emitting device 100.

[0106] Illustratively, the singlet energy level S1(H1) of the first host material H1 is greater than the singlet energy level S1(H2) of the second host material H2; the singlet energy level S1(H2) of the second host material H2 is greater than the singlet energy level S1(D) of the light-emitting material D.

[0107] In some embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level HOMO(H2) of the second host material H2 and the highest occupied molecular orbital energy level HOMO(H1) of the first host material H1 is less than or equal to 0.3 eV. The absolute value of the difference between the lowest occupied molecular orbital energy level LOMO(H2) of the second host material H2 and the lowest occupied molecular orbital energy level LOMO(D) of the luminescent material D is less than or equal to 0.2 eV. The absolute value of the lowest occupied molecular orbital energy level LOMO(H2) of the second host material H2 is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level LOMO(H1) of the first host material H1. The absolute value of the lowest occupied molecular orbital energy level LOMO(D) of the luminescent material D is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level LOMO(H1) of the first host material H1.

[0108] That is, the highest occupied molecular orbital energy level HOMO(H2) of the second host material H2, the highest occupied molecular orbital energy level HOMO(H1) of the first host material H1, the lowest occupied molecular orbital energy level LOMO(H2) of the second host material H2, the lowest occupied molecular orbital energy level LOMO(D) of the luminescent material D, and the lowest occupied molecular orbital energy level LOMO(H1) of the first host material H1 satisfy the following: |HOMO(H1)-HOMO(H2)|≤0.3eV; |LOMO(H2)-LOMO(D)|≤0.2eV; |LOMO(H2)|≥|LOMO(H1)|; |LOMO(D)|≥|LOMO(H1)|.

[0109] By limiting the highest occupied molecular orbital energy level HOMO (H2) of the second host material H2, the highest occupied molecular orbital energy level HOMO (H1) of the first host material H1, the lowest occupied molecular orbital energy level LOMO (H2) of the second host material H2, the lowest occupied molecular orbital energy level LOMO (D) of the luminescent material D, and the lowest occupied molecular orbital energy level LOMO (H1) of the first host material H1, the balanced transfer of electrons and holes can be ensured, so that energy can be better transferred to the first host material H1 and the second host material H2, and then transferred from the first host material H1 and the second host material H2 to the luminescent material D.

[0110] In some embodiments, in each light-emitting layer 131 , a difference between a triplet energy level T1(H1) of the first host material H1 and a triplet energy level T1(D) of the light-emitting material D is greater than or equal to 0.15 eV.

[0111] That is, in each light-emitting layer 131 , the triplet energy level T1(H1) of the first host material H1 and the triplet energy level T1(D) of the light-emitting material D satisfy the following relationship: T1(H1)−T1(D)≥0.15 eV.

[0112] By setting the difference between the triplet energy level T1(H1) of the first host material H1 and the triplet energy level T1(D) of the luminescent material D to be greater than or equal to 0.15 eV, the luminescent material D is configured as a fluorescent material or a delayed fluorescent material, rather than a phosphorescent material. Because the proportion of the second type of luminescent photons in the photons emitted by the fluorescent material or the delayed fluorescent material is relatively small, the delayed luminescence component in the luminescent unit 130 can be reduced, thereby improving the response speed of the luminescent unit 130. When a certain image is displayed for a long time and then switched, the trailing and afterimage phenomena of the displayed image can be effectively reduced.

[0113] In some embodiments, the second host material H2 is a phosphorescent material and includes any one of the ligand groups IA shown in Formula I.

[0114] wherein F is selected from a five-membered or six-membered carbocyclic ring or a carbon heterocyclic ring; and m is selected from any one of 0, 1, 2, 3 and 4.

[0115] Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen.

[0116] The ligand group IA is connected to M, and M is selected from any one of ruthenium, osmium, iridium, palladium, copper, silver and gold; the second main material H2 includes an n-dentate ligand material formed by M with a structure as shown in the general formula I, and the value of n is selected from any one of 3, 4, 5 and 6.

[0117] Ra, Rb and Rc are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

[0118] Furthermore, at least one of Ra, Rb, and Rc contains deuterium. Since deuterium is heavy hydrogen, setting a deuterium substitution on a carbon atom or a nitrogen atom can increase the stability of the chemical bond, thereby improving the thermal stability of the second host material H2. It should be noted that at least one of Ra, Rb, and Rc contains deuterium, which means that at least one of Ra, Rb, and Rc is deuterium, or at least one of Ra, Rb, and Rc is any one of an alkyl group, cycloalkyl group, heteroalkyl group, heterocycloalkyl group, aralkyl group, alkoxy group, aryloxy group, amino group, silanyl group, germanyl group, borane group, selenyl group, alkenyl group, cycloalkenyl group, heteroalkenyl group, alkynyl group, aryl group, heteroaryl group, acyl group, carboxylic acid group, ether, ester, nitrile, isonitrile, sulfenyl group, sulfinyl group, sulfonyl group, and phosphine group containing deuterium.

[0119] It should be noted that the value of m is selected from any one of 0, 1, 2, 3 and 4. That is, when m=0, the F ring does not exist, and the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen does not form a condensed ring; when m=1, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with one F, and F is selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=2, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with two Fs, and the two Fs are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=3, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with three Fs, and the three Fs are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=4, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with four Fs, and the four Fs are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle.

[0120] It can be understood that the second main material H2 includes an n-dentate ligand material formed by M as shown in the general formula I, and the value of n is selected from any one of 3, 4, 5 and 6, that is, the ligand group IA occupies the 1st tooth position and the 2nd tooth position of the n-dentate ligand material, and the 3rd tooth position, ..., and the nth tooth position of the n-dentate ligand material are occupied by other ligand groups. The present disclosure does not limit the structure of the ligand groups occupying the 3rd tooth position, ..., and the nth tooth position of the n-dentate ligand material.

[0121] It should be noted that the position of Rb shown in General Formula I means that Rb can be connected to any of carbon number 6, Z1, Z2, and Z3, that is, Rb can be connected to any element with a substitution position on the six-membered ring formed by carbon numbers 4, 5, and 6 and Z1, Z2, and Z3. The description of Rc can refer to the above description of Rb and is not repeated here.

[0122] The ligand group IA of the second host material H2 including the ligand group IA shown in the general formula I contains a carbene group (i.e., the above-mentioned five-membered carbon heterocycle formed by carbons 1, 2 and 3 and nitrogen), which can realize the emission of short-wavelength light, and the color of the short-wavelength light is, for example, dark blue.

[0123] When the light emitted by the light-emitting device 100 is blue, the light-emitting layer 131 includes the second main material H2. On the one hand, the energy of the second main material H2 can be effectively transferred to the light-emitting material D, thereby improving the luminous efficiency of the light-emitting device 100 and increasing the life of the light-emitting device 100. On the other hand, the second main material H2 is compatible with the preparation process of the light-emitting device in the related art, such as the evaporation process, thereby reducing the manufacturing cost of the light-emitting device. On the other hand, the second main material H2 can increase the number of the second type of luminescent photons in the photons emitted by the light-emitting layer of the blue light-emitting unit 130B, thereby increasing the proportion of the delayed luminescent component in the light-emitting layer of the blue light-emitting unit 130B, and to a certain extent achieving the synchronization of the light-emitting delay of the red light-emitting unit 130R, the green light-emitting unit 130G, and the blue light-emitting unit 130B; when a certain picture is displayed for a long time and then switched, the tailing and afterimage phenomena of the displayed picture can be effectively alleviated.

[0124] In some embodiments, the second host material H2 is selected from any one of the structures shown in the following general formula II;

[0125] wherein F is selected from a five-membered or six-membered carbocyclic ring or a carbon heterocyclic ring; and m is selected from any one of 0, 1, 2, 3 and 4.

[0126] J and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring.

[0127] Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen.

[0128] M is selected from one of platinum and palladium.

[0129] L1 and L2 are the same or different and are independently selected from any one of B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf Rg).

[0130] Ra, Rb, Rc, Re, Rd, Rf and Rg are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

[0131] Furthermore, L1 and L2 are different, and at least one of Ra, Rb, and Rc contains deuterium. Since deuterium is heavy hydrogen, setting a deuterium substitution on a carbon atom or a nitrogen atom can increase the stability of the chemical bond, thereby improving the thermal stability of the second host material H2. It should be noted that at least one of Ra, Rb, and Rc contains deuterium, which means that at least one of Ra, Rb, and Rc is deuterium, or at least one of Ra, Rb, and Rc is any one of an alkyl group, cycloalkyl group, heteroalkyl group, heterocycloalkyl group, aralkyl group, alkoxy group, aryloxy group, amino group, silanyl group, germanyl group, borane group, selenyl group, alkenyl group, cycloalkenyl group, heteroalkenyl group, alkynyl group, aryl group, heteroaryl group, acyl group, carboxylic acid group, ether, ester, nitrile, isonitrile, sulfenyl group, sulfinyl group, sulfonyl group, and phosphine group containing deuterium.

[0132] It should be noted that L1 and L2 are independently selected from any one of B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf Rg). Wherein, B(Rf) is substituted or unsubstituted boron; N(Rf) is substituted or unsubstituted nitrogen; P(Rf) is substituted or unsubstituted phosphorus; O is oxygen; S is sulfur; Se is selenium; C=O is a carbonyl group, S=O is a sulfinyl group; SO2 is a sulfone group; C(Rf Rg) is substituted or unsubstituted carbon; Si(Rf Rg) is substituted or unsubstituted silicon; Ge(Rf Rg) is substituted or unsubstituted germanium.

[0133] It should be noted that the description of m here can refer to the above description of m; the description of Rb, Rc, Re, Rd, and Rf can refer to the above description of Rb, which will not be repeated here.

[0134] In some embodiments, J and E are not both five-membered carbocyclic rings or carboheterocyclic rings. This is because when J and E are both five-membered carbocyclic rings or carboheterocyclic rings, the stability of the resulting compound is relatively poor. The arrangement of J and E being not both five-membered carbocyclic rings or carboheterocyclic rings can improve the stability of the second host material H2.

[0135] Exemplarily, when M is platinum, m=0, L1 is oxygen, L2 is nitrogen, Z1, Z2 and Z3 are carbon, J and E are six-membered carbon rings and Re is fused with Rf, Ra, Rb, Rc, Re, Rd and Rf are the same or different, and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino, and at least one of Ra, Rb and Rc is a deuterated methyl group, the structural formula of the second host material H2 can be as shown below.

[0136] Exemplarily, when M is platinum, m=1, L1 is oxygen, L2 is nitrogen, Z1, Z2 and Z3 are carbon, J and E are six-membered carbon rings and Re is fused with Rf, Ra, Rb, Rc, Re, Rd and Rf are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino, and at least one of Ra, Rb and Rc contains deuterium, the structural formula of the second host material H2 can be as shown below.

[0137] Exemplarily, when M is platinum, m=0, L1 is silicon, L2 is nitrogen, Z1, Z2 and Z3 are carbon, J and E are six-membered carbon rings and Re is fused with Rf, Rb, Rc, Re, Rd, Rf and Rg are the same or different, and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino, and Ra is a deuterated methyl group, the structural formula of the second host material H2 can be as shown below.

[0138] Exemplarily, when M is platinum, m=1, L1 is silicon, L2 is nitrogen, Z1, Z2 and Z3 are carbon, J and E are six-membered carbon rings and Re is fused with Rf, Rb, Rc, Re, Rd, Rf and Rg are the same or different, and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino, and Ra is a deuterated methyl group, the structural formula of the second host material H2 can be as shown below.

[0139] It should be noted that the above-listed structural formulas are examples of the structure of the second host material H2 and are not intended to limit the structure of the second host material H2. H2-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0140] In some embodiments, the weight percentage of the second host material H2 (phosphorescent material) in the light-emitting layer 131 is greater than or equal to 10% and less than or equal to 50%. For example, the weight percentage of the second host material H2 in the light-emitting layer 131 is 10%, 20%, 30%, 35%, 40%, or 50%. If the weight percentage of the second host material H2 in the light-emitting layer 131 is less than 10%, the charge transfer efficiency is reduced, resulting in a decrease in the luminous efficiency of the light-emitting device 100. If the weight percentage of the second host material H2 in the light-emitting layer 131 is greater than 50%, the luminous efficiency of the light-emitting device 100 is reduced.

[0141] In other embodiments, the second host material H2 is a delayed fluorescent material selected from any one of the structures shown in the following general formulas I and II;

[0142] Wherein, X1 and X2 are the same or different and are independently selected from one of carbon and nitrogen.

[0143] R1, R2, R3 and R4 are the same or different and are independently selected from a substituted or unsubstituted substituent group IIIA and a substituted or unsubstituted substituent group IIIB. Among R1, R2, R3 and R4, there are at least two substituted or unsubstituted substituent groups IIIA and at least one substituted or unsubstituted substituent group IIIB.

[0144] The substituent group IIIA is selected from any one of IIIA-a to IIIA-i.

[0145] Here, Z is selected from any one of carbon, nitrogen, oxygen and sulfur.

[0146] Rh is selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thio, sulfinyl, sulfonyl and phosphino.

[0147] The substituent group IIIB is selected from any one of IIIB-a to IIIB-j.

[0148] Wherein, X3 is selected from one of oxygen and sulfur.

[0149] Rj is selected from any one of hydrogen, deuterium, halogen, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted haloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted haloalkoxy, substituted or unsubstituted aryl, substituted or unsubstituted haloaryl, substituted or unsubstituted silyl and substituted or unsubstituted heterocycle.

[0150] It should be noted that the two benzene rings in IIIA-a can be connected by a single bond to form a substituted or unsubstituted IIIA-a-1, the structural formula of which can be shown as follows.

[0151] It should be noted that the above structural formulas are examples of the structures of substituent groups IIIA and IIIB, and are not intended to limit their structures. IIIA-x and IIIB-x in the above structural formulas are aliases for each structural formula and are not part of the structural formula.

[0152] When the light-emitting layer 131 includes a first host material H1, a second host material H2, and a light-emitting material D, the second host material H2 selected from the structures represented by general formulas I and II can reduce the number of second-type photons in the photons emitted by the light-emitting layers of the red light-emitting unit 130R and the green light-emitting unit 130G, thereby reducing the proportion of delayed-emission components in the photons emitted by the light-emitting layers of the red light-emitting unit 130R and the green light-emitting unit 130G, thereby improving the response speed of the red light-emitting unit 130R and the green light-emitting unit 130G. Simultaneously, the second host material H2 can increase the number of second-type photons in the photons emitted by the light-emitting layer of the blue light-emitting unit 130B, thereby increasing the proportion of delayed-emission components in the light-emitting layer of the blue light-emitting unit 130B, thereby achieving synchronization of the light emission delays of the red light-emitting unit 130R, the green light-emitting unit 130G, and the blue light-emitting unit 130B. This can effectively reduce the smearing and afterimage effects of the displayed image when switching after displaying a certain image for a long time. The light-emitting material D is, for example, a fluorescent material. On the other hand, the second host material H2 selected from the structure shown in general formula III is compatible with the preparation process of the light-emitting device in the related art, such as the evaporation process, thereby reducing the manufacturing cost of the light-emitting device.

[0153] Illustratively, when X1 and X2 are substituted or unsubstituted carbon, at least two of R1, R2, R3 and R4 are IIIA-a-1, and at least one is IIIB-j, the structural formula of the second host material H2 can be as shown below.

[0154] For example, when X1 and X2 are substituted or unsubstituted carbon, and R1, R2, R3 and R4 are IIIA-a-1, IIIA-i, IIIA-h, and IIIB-j, respectively, the structural formula of the second host material H2 can be as shown below.

[0155] For example, when X1 and X2 are substituted or unsubstituted carbon, three of R1, R2, R3 and R4 are substituted IIIA-a-1, and one is IIIB-j, the structural formula of the second host material H2 can be as shown below.

[0156] For example, when X1 and X2 are substituted or unsubstituted carbon, one of R1, R2, R3 and R4 is substituted or unsubstituted IIIA-g, and one is IIIB-a, the structural formula of the second host material H2 can be as shown below.

[0157] For example, when X1 and X2 are substituted or unsubstituted carbon, and R1, R2, R3 and R4 include IIIA-a-1, IIIB-j and unsubstituted IIIB-a, the structural formula of the second host material H2 can be as shown below.

[0158] It should be noted that the above-listed structural formulas are examples of the structure of the second host material H2 and are not intended to limit the structure of the second host material H2. H2-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0159] In some embodiments, the weight percentage of the second host material H2 (delayed fluorescent material) in the light-emitting layer 131 is greater than or equal to 20% and less than or equal to 55%. For example, the weight percentage of the second host material H2 in the light-emitting layer 131 is 20%, 25%, 30%, 40%, 50%, or 55%. When the weight percentage of the second host material H2 in the light-emitting layer 131 is less than 20%, the energy transfer function from the second host material H2 to the light-emitting material D cannot meet the requirements, resulting in excessive light emission from the second host material H2 and a significant delay effect. When the weight percentage of the second host material H2 in the light-emitting layer 131 is greater than 55%, the luminous efficiency of the light-emitting device 100 is reduced.

[0160] In some embodiments, the mass fraction of the second host material H2 in the light-emitting layer 131 is less than or equal to the mass fraction of the first host material H1 in the light-emitting layer 131. When the mass fraction of the second host material H2 in the light-emitting layer 131 is greater than the mass fraction of the first host material H1 in the light-emitting layer 131, the luminous efficiency of the light-emitting device 100 is reduced.

[0161] Illustratively, the mass proportion of the second host material H2 in the light-emitting layer 131 is smaller than the mass proportion of the first host material H1 in the light-emitting layer 131 .

[0162] In some embodiments, referring to FIG. 4 , the light emitting unit 130 includes a plurality of light emitting layers 131 , and the plurality of light emitting layers 131 are stacked along a first direction X.

[0163] When the light-emitting unit 130 includes a plurality of light-emitting layers 131, the plurality of light-emitting layers 131 are stacked from the first electrode 110 toward the second electrode 120 in the first direction X. The light intensity emitted by each light-emitting unit 130 of the light-emitting device 100 is lower than the light intensity emitted by the light-emitting unit 130 of the single-layer light-emitting device 100, thereby improving the life of the light-emitting device 100.

[0164] It should be noted that when the light-emitting unit 130 includes multiple light-emitting layers 131, the number of material types in each of the multiple light-emitting layers 131 must be consistent. For example, if the light-emitting layer 131 of the light-emitting unit 130 includes a first host material H1, a second host material H2, and a light-emitting material D, then each of the multiple light-emitting layers 131 includes the first host material H1, the second host material H2, and the light-emitting material D. Alternatively, if the light-emitting layer 131 of the light-emitting unit 130 includes a first host material H1 and a light-emitting material D, then each of the multiple light-emitting layers 131 includes the first host material H1 and the light-emitting material D. However, the structure corresponding to each material can be different. For example, if the first host material H1 of the first light-emitting layer 131 in the multiple light-emitting layers 131 is H1-1, then the first host material H1 of the second light-emitting layer 131 in the multiple light-emitting layers 131 can be H1-2, H1-4, H1-10, etc. The description of the second host material H2 and the luminescent material D can refer to the above description of the first host material H1, which will not be repeated here.

[0165] In order to objectively evaluate the technical effects of the embodiments of the present disclosure, the technical solutions provided by the present disclosure will be described in detail and exemplarily through the following experimental examples and comparative examples.

[0166] The following embodiments and comparative examples use different materials to make the light-emitting layer 131 of the light-emitting device 100, and compare the voltage, luminous efficiency, device life, the difference ΔBR between the ratio of the number of first-type light-emitting photons between the blue light-emitting unit 130B and the red light-emitting unit 130R to the number of photons emitted by the light-emitting unit 130, the difference ΔBG between the ratio of the number of first-type light-emitting photons between the blue light-emitting unit 130B and the green light-emitting unit 130G to the number of photons emitted by the light-emitting unit 130, and the difference ΔGR between the ratio of the number of first-type light-emitting photons between the green light-emitting unit 130G and the red light-emitting unit 130R.

[0167] In the following comparative examples and embodiments, the structure of the light emitting device 100 and the test conditions of the light emitting device 100 are the same.

[0168] For example, referring to FIG5 , the method for preparing the light-emitting device 100 is as follows: using the material of the first electrode 110 (indium tin oxide), the material of the hole injection layer 140, the material of the hole transport layer 150, the material of the electron blocking layer 160, the material of the light-emitting layer 131, the material of the hole blocking layer 190, the material of the electron transport layer 180, the material of the electron injection layer 170, and the material of the second electrode 120, the first electrode 110, the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the light-emitting layer 131, the hole blocking layer 190, the electron transport layer 180, the electron injection layer 170, and the second electrode 120 are sequentially formed on the backplane. The process for forming the first electrode 110, the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the light-emitting functional layer 212, the hole blocking layer 190, the electron transport layer 180, the electron injection layer 170, and the second electrode 120 is, for example, an evaporation process.

[0169] The light-emitting layer formed includes a first light-emitting layer 131B that emits blue light, a second light-emitting layer 131G that emits green light, and a third light-emitting layer 131R that emits red light, and the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R are arranged along the second direction Y; the first light-emitting layer 131B is the light-emitting layer of the blue light-emitting unit 130B, the second light-emitting layer 131G is the light-emitting layer of the green light-emitting unit 130G, and the third light-emitting layer 131R is the light-emitting layer of the red light-emitting unit 130B. The first electrode 110 includes a first electrode 110A, a first electrode 110B, and a first electrode 110C, and the first electrodes 110A, 110B, and 110C are arranged along the second direction Y. The electron blocking layer 160 includes an electron blocking layer 160A, an electron blocking layer 160B, and an electron blocking layer 160C, and the electron blocking layers 160A, 160B, and 160C are arranged along the second direction Y. The first electrode 110A, the electron blocking layer 160A, and the first light-emitting layer 131B are directly opposite each other along the first direction X; the first electrode 110B, the electron blocking layer 160B, and the second light-emitting layer 131G are directly opposite each other along the first direction X; and the first electrode 110C, the electron blocking layer 160C, and the third light-emitting layer 131R are directly opposite each other along the first direction X.

[0170] It should be noted that the light-emitting device 100 in the comparative example and the embodiment is a light-emitting device 100 having a single-layer light-emitting layer 131, that is, each light-emitting unit 130 includes a light-emitting layer 131. The thickness and material of the first electrode 110, hole injection layer 140, hole transport layer 150, electron blocking layer 160, hole blocking layer 190, electron transport layer 180, electron injection layer 170, and second electrode 120 in the embodiment and the comparative example are the same, but the material and thickness of the light-emitting functional layer 212 are different.

[0171] The materials of the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R include a first host material H1 and a light-emitting material D. The light-emitting material D involved in the following comparative examples and embodiments includes:

[0172] It should be noted that RD-1, GD-1, BD-1, RD-2, and GD-1 in the above structural formulas are aliases for each structural formula and are not part of the structural formula structure.

[0173] The thickness and materials of the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of the embodiment and the comparative example are described below.

[0174] In the comparative example, the thickness of first light-emitting layer 131B was 20 nm. The structural formula of the first host material H1 of first light-emitting layer 131B was shown in H1-17. The structural formula of the light-emitting material D of first light-emitting layer 131B was shown in BD-1. The mass fraction of light-emitting material D in first light-emitting layer 131B was 1%. No second host material H2 was added to first light-emitting layer 131B. The thickness of second light-emitting layer 131G was 35 nm. The structural formula of the first host material H1 of second light-emitting layer 131G was shown in H1-18. The structural formula of the light-emitting material D of second light-emitting layer 131G was shown in GD-1. The mass fraction of light-emitting material D in second light-emitting layer 131G was 10%. No second host material H2 was added to second light-emitting layer 131G. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-18. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-1. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 7%. The second main material H2 is not added to the third light-emitting layer 131R.

[0175] In Example 1, the thickness of first light-emitting layer 131B is 40 nm. The structural formula of the first host material H1 of first light-emitting layer 131B is shown in H1-19. The structural formula of the light-emitting material D of first light-emitting layer 131B is shown in BD-1. The weight percentage of light-emitting material D in first light-emitting layer 131B is 1%. The structural formula of the second host material H2 of first light-emitting layer 131B is shown in H2-19. The weight percentage of second host material H2 in first light-emitting layer 131B is 30%. The thickness of second light-emitting layer 131G is 35 nm. The structural formula of the first host material H1 of second light-emitting layer 131G is shown in H1-18. The structural formula of the light-emitting material D of second light-emitting layer 131G is shown in GD-1. The weight percentage of light-emitting material D in second light-emitting layer 131G is 10%. No second host material H2 is added to second light-emitting layer 131G. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-18. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-1. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 7%. The second main material H2 is not added to the third light-emitting layer 131R.

[0176] In Example 2, the thickness of first light-emitting layer 131B is 40 nm. The structural formula of the first host material H1 of first light-emitting layer 131B is shown in H1-19. The structural formula of the light-emitting material D of first light-emitting layer 131B is shown in BD-1. The weight percentage of light-emitting material D in first light-emitting layer 131B is 1%. The structural formula of the second host material H2 of first light-emitting layer 131B is shown in H2-4. The weight percentage of second host material H2 in first light-emitting layer 131B is 15%. The thickness of second light-emitting layer 131G is 35 nm. The structural formula of the first host material H1 of second light-emitting layer 131G is shown in H1-18. The structural formula of the light-emitting material D of second light-emitting layer 131G is shown in GD-1. The weight percentage of light-emitting material D in second light-emitting layer 131G is 10%. No second host material H2 is added to second light-emitting layer 131G. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-18. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-1. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 7%. The second main material H2 is not added to the third light-emitting layer 131R.

[0177] In Example 3, the thickness of first light-emitting layer 131B is 20 nm. The structural formula of the first host material H1 of first light-emitting layer 131B is shown in H1-17. The structural formula of the light-emitting material D of first light-emitting layer 131B is shown in BD-1. The weight percentage of light-emitting material D in first light-emitting layer 131B is 1%. No second host material H2 is added to first light-emitting layer 131B. The thickness of second light-emitting layer 131G is 35 nm. The structural formula of the first host material H1 of second light-emitting layer 131G is shown in H1-2. The structural formula of the light-emitting material D of second light-emitting layer 131G is shown in GD-2. The weight percentage of light-emitting material D in second light-emitting layer 131G is 1%. The structural formula of the second host material H2 of second light-emitting layer 131G is shown in H2-16. The weight percentage of second host material H2 in second light-emitting layer 131G is 30%. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-6. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-2. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 1%. The structural formula of the second main material H2 of the third light-emitting layer 131R is shown as H2-10. The mass proportion of the second main material H2 in the third light-emitting layer 131R is 20%.

[0178] In Example 4, the thickness of the first light-emitting layer 131B is 20 nm. The structural formula of the first host material H1 of the first light-emitting layer 131B is shown in H1-17. The structural formula of the light-emitting material D of the first light-emitting layer 131B is shown in BD-1. The weight percentage of the light-emitting material D in the first light-emitting layer 131B is 1%. No second host material H2 is added to the first light-emitting layer 131B. The thickness of the second light-emitting layer 131G is 35 nm. The structural formula of the first host material H1 of the second light-emitting layer 131G is shown in H1-8. The structural formula of the light-emitting material D of the second light-emitting layer 131G is shown in GD-2. The weight percentage of the light-emitting material D in the second light-emitting layer 131G is 1%. The structural formula of the second host material H2 of the second light-emitting layer 131G is shown in H2-16. The second host material H2 in the second light-emitting layer 131G is 30%. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-6. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-2. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 1%. The structural formula of the second main material H2 of the third light-emitting layer 131R is shown as H2-10. The mass proportion of the second main material H2 in the third light-emitting layer 131R is 35%.

[0179] In Example 5, the thickness of first light-emitting layer 131B is 40 nm. The structural formula of the first host material H1 of first light-emitting layer 131B is shown in H1-19. The structural formula of the light-emitting material D of first light-emitting layer 131B is shown in BD-1. The weight percentage of light-emitting material D in first light-emitting layer 131B is 1%. The structural formula of the second host material H2 of first light-emitting layer 131B is shown in H2-19. The weight percentage of second host material H2 in first light-emitting layer 131B is 30%. The thickness of second light-emitting layer 131G is 35 nm. The structural formula of the first host material H1 of second light-emitting layer 131G is shown in H1-8. The structural formula of the light-emitting material D of second light-emitting layer 131G is shown in GD-2. The weight percentage of light-emitting material D in second light-emitting layer 131G is 1%. The structural formula of the second host material H2 of second light-emitting layer 131G is shown in H2-16. The weight percentage of second host material H2 in second light-emitting layer 131G is 30%. The thickness of the third light-emitting layer 131R is 45 nm. The structural formula of the first main material H1 of the third light-emitting layer 131R is shown as H1-6. The structural formula of the light-emitting material D of the third light-emitting layer 131R is shown as RD-2. The mass proportion of the light-emitting material D in the third light-emitting layer 131R is 1%. The structural formula of the second main material H2 of the third light-emitting layer 131R is shown as H2-10. The mass proportion of the second main material H2 in the third light-emitting layer 131R is 35%.

[0180] In order to more clearly describe the differences in the structural formulas of the first host material H1, the second host material H2, and the light-emitting material D used in the embodiment and the comparative example, the differences in their mass proportions in the light-emitting layer 131, and the thickness of the light-emitting layer 131, the following Table 1 is used to more clearly show the structural formulas of the first host material H1, the second host material H2, and the light-emitting material D used in the embodiment and the comparative example, the differences in their mass proportions in the light-emitting layer 131, and the thickness of the light-emitting layer 131.

[0181] Table 1

[0182] It should be noted that the " / " in Table 1 indicates that the second host material H2 is not added to the light-emitting layer 131. For example, in the first light-emitting layer 131B of the comparative example, the sub-grid corresponding to the second host material H2 and its mass fraction is " / ", indicating that the first light-emitting layer 131B of the comparative example does not contain the second host material H2. "Ax; y%" in Table 1 indicates that the corresponding structural formula is Ax and the corresponding mass fraction is y%. For example, in the first light-emitting layer 131B of the comparative example, the sub-grid corresponding to the light-emitting material D and its mass fraction is "BD-1; 1%", indicating that in the first light-emitting layer 131B of the comparative example, the structural formula of light-emitting material D is shown as BD-1, and the mass fraction of light-emitting material D in the first light-emitting layer 131B is 1%. The structural formulas represented by H1-x, H2-x, BD-x, GD-x, and RD-x (x is a positive integer) are as described above and are not repeated here.

[0183] The highest occupied molecular orbital energy level (HOMO), the lowest occupied molecular orbital energy level (LOMO), and the triplet energy level (T1) of the first host material H1 and the second host material H2 shown in Table 1 are shown in Table 2.

[0184] Table 2

[0185] Based on the above materials, the voltage (V), luminous efficiency (cd / A) and device life (h) performance of the light-emitting device 100 of Examples 1 to 5 and the comparative example were tested. The data structure was based on the comparative example. The test results are shown in Table 3 below.

[0186] Table 3

[0187] As can be seen from Table 3, taking the test data of the comparative example as a reference, setting its voltage, luminous efficiency, and device life data to 100%, compared with the comparative example, when the second host material H2 is added to the first light-emitting layer 131B, the luminous efficiency of Examples 1 to 5 is significantly improved; when the second host material H2 is added to the second light-emitting layer 131G, the luminous efficiency and the device life are both improved; when the second host material H2 is added to the third light-emitting layer 131R, the device life is improved.

[0188] Based on the above materials, the differences ΔBR, ΔBG, and ΔGR between the ratios of the number of first-type luminous photons to the number of photons emitted by the light-emitting layer 131 between any two light-emitting layers 131 in the light-emitting devices 100 of Examples 1 to 5 and the comparative example are calculated. Here, for the meanings of ΔBR, ΔBG, and ΔGR, please refer to the above content and will not be repeated here. The specific calculation method is as follows: first, by measuring, the ratio E1 of the number of first-type luminous photons of each light-emitting layer 131 to the number of photons emitted by the light-emitting layer 131 (hereinafter referred to as the instantaneous luminescence ratio E1) and the ratio E2 of the number of second-type luminous photons to the number of photons emitted by the light-emitting layer 131 (hereinafter referred to as the delayed luminescence ratio E2) are obtained, and then the absolute value of the difference between the instantaneous luminescence ratios E1 of the two light-emitting layers 131 is calculated.

[0189] The above-mentioned method for measuring the instantaneous luminescence proportion E1 and the delayed luminescence proportion E2 of each light-emitting layer 131 is, for example, obtained by fitting and calculating the transient attenuation curves as mentioned above. The transient attenuation curves corresponding to the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of Example 1 are shown in FIG6 ; the transient attenuation curves corresponding to the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of Example 2 are shown in FIG7 ; the transient attenuation curves corresponding to the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of Example 3 are shown in FIG8 ; the transient attenuation curves corresponding to the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of Example 4 are shown in FIG9 ; the transient attenuation curves corresponding to the first light-emitting layer 131B, the second light-emitting layer 131G, and the third light-emitting layer 131R of Example 5 are shown in FIG10 .

[0190] It should be noted that the number of photons under normalized conditions in Figures 6 to 10 refers to the number of photons under the condition that the number of photons emitted by the light-emitting layer 131 is normalized to 1, that is, the number of photons emitted at a certain moment in the figure is the ratio of the number of photons emitted at that moment to the number of photons emitted by the light-emitting layer 131.

[0191] Specifically, ΔBR is the absolute value of the difference between the instantaneous luminescence ratio B-E1 of the first light-emitting layer 131B and the instantaneous luminescence ratio R-E1 of the third light-emitting layer 131R; ΔBG is the absolute value of the difference between the instantaneous luminescence ratio B-E1 of the first light-emitting layer 131B and the instantaneous luminescence ratio G-E1 of the second light-emitting layer 131G; ΔGR is the absolute value of the difference between the instantaneous luminescence ratio G-E1 of the second light-emitting layer 131G and the instantaneous luminescence ratio R-E1 of the third light-emitting layer 131R. It should be noted that the ΔGR calculated using this method is the same as the ΔGR calculated using the above formula (1). Those skilled in the art will understand that G-E1 in this method is the same as G-E1 in formula (1).

[0192] The calculation results of ΔBR, ΔBG, and ΔGR are shown in Table 4 below.

[0193] Table 4

[0194] Compared with the comparative example, the ΔBR and ΔBG of Example 1 and Example 2 are significantly reduced, and both Example 1 and Example 2 show that the ΔBR, ΔBG, and ΔGR tend to be consistent. This is because Example 1 adds a second host material H2-19 (delayed fluorescent material) to the first light-emitting layer 131B, and Example 2 adds a second host material H2-4 (phosphorescent material) to the first light-emitting layer 131B. The second host materials H2-19 and H2-4 are configured to increase energy transfer. Since the exciton utilization rate of the triplet energy level of the second host material H2 is much higher than the exciton utilization rate of the triplet energy level of the first host material H1 in the comparative example, the number of second-type luminescent photons in the photons emitted by the first light-emitting layer 131B increases, and the proportion of delayed luminescence increases, thereby reducing the difference in the delayed luminescence proportion between the first light-emitting layer 131B and the second light-emitting layer 131G, and between the first light-emitting layer 131B and the third light-emitting layer 131R, thereby achieving synchronization of the luminescence delay of the first light-emitting layer 131B, the second light-emitting layer 131G and the third light-emitting layer 131R, that is, achieving synchronization of the R, G and B color delays. At the same time, compared with the comparative example, the device efficiency is greatly improved, and at the same brightness, the device life can be further improved.

[0195] Compared with the comparative example, the ΔBR, ΔBG, and ΔGR of Example 3 and Example 4 are significantly reduced, and the ΔBR and ΔBG of Example 4 are significantly reduced, and both Examples 3 and 4 show that the ΔBR, ΔBG, and ΔGR tend to be consistent. This is because in Example 3 and Example 4, a second host material H2-16 is added to the second light-emitting layer 131G, and a second host material H2-10 is added to the third light-emitting layer 131R. The second host materials H2-16 and H2-10 are configured to increase energy transfer, which can generate excitons on the second host material H2 and transfer the exciton energy to the light-emitting material D for luminescence. This can accelerate the delayed lifetime of the triplet energy level on the second host material H2. Compared with the comparative example, among the photons emitted by the third light-emitting layer 131R and the second light-emitting layer 131G, the number of second-type luminescent photons is reduced, and the proportion of delayed luminescence is reduced, thereby reducing the difference in the proportion of delayed luminescence between the first light-emitting layer 131B and the second light-emitting layer 131G, and between the first light-emitting layer 131B and the third light-emitting layer 131R, thereby achieving synchronization of the luminescence delay of the first light-emitting layer 131B, the second light-emitting layer 131G and the third light-emitting layer 131R, that is, achieving synchronization of the R, G and B color delays. Meanwhile, compared with the comparative example, the internal quantum efficiency in the light-emitting layer 131 can theoretically reach 100%, and the device efficiency performance is better.

[0196] Compared with Example 4, Example 3 shows a significantly lower ΔBR in Example 4, and ΔBR, ΔBG, and ΔGR are more consistent. This is because the first host material H1 of the second light-emitting layer 131G in Example 3 is H1-2, while the first host material H1 of the second light-emitting layer 131G in Example 4 is H1-8. Consequently, the triplet energy levels of the first host material H1 of the second light-emitting layer 131G in Examples 3 and 4 are different. Furthermore, in Example 4, the triplet energy level difference between the first host material H1 and the second host material H2 of the second light-emitting layer 131G is relatively large. When the triplet energy level difference between the first host material H1 and the second host material H2 is relatively large, the leakage of excitons from the second host material H2 to the first host material H1 can be better suppressed, reducing energy relaxation channels. Consequently, the number of second-type luminescent photons emitted by the second light-emitting layer 131G is reduced, and the proportion of delayed luminescence is reduced.

[0197] Example 5 is an example obtained by further optimizing Example 3 and Example 4, that is, a second main material H2 is added to the first light-emitting layer 131B, the second light-emitting layer 131G and the third light-emitting layer 131R, and the same light-emitting mechanism is adopted, which is more conducive to adjusting the proportion of instantaneous luminescence and delayed luminescence in the three light-emitting layers 131, thereby achieving high efficiency, long life and low delay device performance.

[0198] It can be seen that by adding the second main material H2 to the light-emitting layer 131, the proportion of instantaneous delayed luminescence and the proportion of delayed luminescence in the three light-emitting layers 131 can be adjusted, thereby effectively reducing the response speed difference between different light-emitting layers, and achieving high-efficiency, long-life, and low-delay sensitization device performance, thereby effectively improving the problem of tailing or afterimage, and achieving high-quality picture quality display effects.

[0199] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in the present disclosure should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A light emitting device, comprising: A first electrode and a second electrode stacked along a first direction; at least two light-emitting units disposed between the first electrode and the second electrode; The at least two light emitting units are arranged along a second direction, and the second direction intersects with the first direction; The photons emitted by each of the at least two light-emitting units include: a first type of light-emitting photons and a second type of light-emitting photons, wherein the emission time of the first type of light-emitting photons is shorter than the emission time of the second type of light-emitting photons; The number of the second type of luminous photons emitted by at least one light-emitting unit is less than or equal to the number of the first type of luminous photons.

2. The light emitting device according to claim 1, wherein: The at least two light-emitting units include at least three light-emitting units, and the at least three light-emitting units are arranged along the second direction; Under normalized conditions, between any two light-emitting units, the difference between the ratio of the number of photons of the first type of light emission to the number of photons emitted by the light-emitting units is less than or equal to 40%.

3. The light emitting device according to claim 1 or 2, wherein: Each of the at least two light-emitting units comprises at least one light-emitting layer; Each of the at least one light-emitting layer comprises: a first host material and a light-emitting material; at least one of the light-emitting layers further comprises: a second host material; The triplet energy level of the second host material is less than or equal to the triplet energy level of the first host material; the triplet energy level of the second host material is greater than or equal to the triplet energy level of the luminescent material.

4. The light emitting device according to claim 3, wherein: The difference between the triplet energy level of the first host material and the triplet energy level of the second host material is greater than or equal to 0.1 eV; the difference between the triplet energy level of the second host material and the triplet energy level of the luminescent material is greater than or equal to 0.1 eV.

5. The light emitting device according to claim 3 or 4, wherein: The difference between the peak wavelength of the emission spectrum of the second host material and the peak wavelength of the absorption spectrum of the luminescent material is less than or equal to 40 nm.

6. The light emitting device according to any one of claims 3 to 5, wherein: The difference between the peak wavelength of the emission spectrum of the second host material and the peak wavelength of the absorption spectrum of the luminescent material is less than or equal to 30 nm.

7. The light emitting device according to any one of claims 3 to 6, wherein: The singlet energy level of the first host material is greater than or equal to the singlet energy level of the second host material; the singlet energy level of the second host material is greater than or equal to the singlet energy level of the luminescent material.

8. The light emitting device according to any one of claims 3 to 7, wherein: The absolute value of the difference between the highest occupied molecular orbital energy level of the second host material and the highest occupied molecular orbital energy level of the first host material is less than or equal to 0.3 eV; The lowest occupied molecular orbital energy level of the second host material is equal to the lowest occupied molecular orbital energy level of the luminescent material. The absolute value of the difference between the levels is less than or equal to 0.2 eV; The absolute value of the lowest occupied molecular orbital energy level of the second host material is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level of the first host material; The absolute value of the lowest occupied molecular orbital energy level of the luminescent material is greater than or equal to the absolute value of the lowest occupied molecular orbital energy level of the first host material.

9. The light emitting device according to any one of claims 3 to 8, wherein: In each of the light-emitting layers: a difference between a triplet energy level of the first host material and a triplet energy level of the light-emitting material is greater than or equal to 0.15 eV.

10. The light emitting device according to any one of claims 3 to 9, wherein: The second host material includes any one of the ligand groups IA shown in general formula I; wherein F is selected from a five-membered or six-membered carbocyclic or carbon heterocyclic ring; the value of m is selected from any one of 0, 1, 2, 3 and 4; Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen; The ligand group IA is connected to M, and M is selected from any one of ruthenium, osmium, iridium, palladium, copper, silver and gold; the second host material includes an n-dentate ligand material having a structure as shown in the general formula I formed by M, and the value of n is selected from any one of 3, 4, 5 and 6; Ra, Rb and Rc are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

11. The light emitting device according to any one of claims 3 to 10, wherein: The second main material is selected from any one of the structures shown in the following general formula Ⅱ; Wherein, F is selected from a five-membered or six-membered carbocyclic ring or a carbocyclic heterocyclic ring; the value of m is selected from any one of 0, 1, 2, 3 and 4; J and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic or carbon heterocyclic ring; Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen; M is selected from one of platinum and palladium; L1 and L2 are the same or different and are independently selected from any one of B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf Rg); Ra, Rb, Rc, Re, Rd, Rf and Rg are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenanyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

12. The light emitting device according to claim 11, wherein: J and E are not simultaneously a five-membered carbocyclic ring or a five-membered heterocyclic ring.

13. The light emitting device according to claim 11 or 12, wherein: L1 and L2 are different.

14. The light emitting device according to any one of claims 10 to 13, wherein: At least one of Ra, Rb and Rc contains deuterium.

15. The light emitting device according to any one of claims 10 to 14, wherein: The mass proportion of the second host material in the light-emitting layer is greater than or equal to 10% and less than or equal to 50%.

16. The light emitting device according to any one of claims 3 to 9, wherein: The second main material is selected from any one of the structures shown in the following general formula I and II; Wherein, X1 and X2 are the same or different and are independently selected from one of carbon and nitrogen; R1, R2, R3 and R4 are the same or different and are independently selected from a substituted or unsubstituted substituent group IIIA and a substituted or unsubstituted substituent group IIIB, and among R1, R2, R3 and R4, there are at least two substituted or unsubstituted substituent groups IIIA and at least one substituted or unsubstituted substituent group IIIB; The substituent group IIIA is selected from any one of IIIA-a to IIIA-i; Wherein, Z is selected from any one of carbon, nitrogen, oxygen and sulfur; Rh is selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl and phosphino; The substituent group IIIB is selected from any one of IIIB-a to IIIB-j; Wherein, X3 is selected from one of oxygen and sulfur; Rj is selected from any one of hydrogen, deuterium, halogen, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted haloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted haloalkoxy, substituted or unsubstituted aryl, substituted or unsubstituted haloaryl, substituted or unsubstituted silyl and substituted or unsubstituted heterocycle.

17. The light emitting device according to claim 16, wherein: The mass proportion of the second host material in the light-emitting layer is greater than or equal to 20% and less than or equal to 55%.

18. The light emitting device according to any one of claims 3 to 17, wherein: The mass proportion of the second host material in the light-emitting layer is less than or equal to the mass proportion of the first host material in the light-emitting layer.

19. The light emitting device according to any one of claims 1 to 18, wherein: The light emitting unit includes a plurality of light emitting layers, and the plurality of light emitting layers are stacked along the first direction.

20. A display panel comprising the light emitting device according to any one of claims 1 to 19; Also includes: A driving circuit is used to drive the light emitting device to emit light.

21. A display device comprising the display panel according to claim 20; Also includes: A driving chip is used to drive the display panel to display.

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