High-efficiency and long-service-life dimmable organic light-emitting device and use thereof

Abstract

The present invention relates to a high-efficiency and long-service-life dimmable organic light-emitting device and a use thereof. The light-emitting device comprises: a light-emitting layer. In the light-emitting layer, two or more host materials are mixed together and a luminescent material is doped in the layer; the luminescent material is a platinum complex, and the luminescent material emits light in a monomer emission state and at least one aggregation emission state; the LUMO energy level of at least one host material is lower than the LUMO energy level of the luminescent material or the difference between the LUMO energy level of at least one host material and the LUMO energy level of the luminescent material is less than 0.2 eV, or the host material in the light-emitting layer employs a combination of SF-BCZ and SF-TRZ. The light-emitting layer or the light-emitting device can be applied to fixed visual display units, mobile visual display units, lighting units, keyboards, clothing, decorative items, clothing accessories, wearable devices, medical monitoring devices, wallpapers, tablet computers, laptops, advertising panels, panel display units, household appliances, and office supplies.

Description

A high-efficiency, long-life adjustable organic light-emitting device and its application Technical Field

[0001] The present invention relates to the technical field of OLED lighting, and in particular to a high-efficiency, long-life, dimmable organic light-emitting device and applications thereof. Background Art

[0002] For color-tunable OLEDs (CT-OLEDs), the solution of using two or more emitters or three or more light-emitting layers or two or more sub-OLEDs to achieve color tunability has many disadvantages. By simplifying the device structure so that only a single emitter is required, problems such as "color aging" that reduce device life due to different lifespans between different emitters can be avoided.

[0003] The prior art discloses many technologies for realizing color-tunable OLEDs. For example, CN102280592A discloses an organic electroluminescent device that realizes color-tunable emission based on a single luminescent material; CN116602071A discloses a color-tunable OLED with a long operating life; and CN110945669A discloses a color-tunable organic light-emitting diode device based on a single emitter and a method thereof.

[0004] However, the existing color-adjustable OLED devices (or light-emitting devices) have many defects such as low efficiency, poor stability, and small adjustable light range, which need to be solved urgently. For example, for the device with Pt-X-4 used in CN116602071A, its LT 90@100nits The estimated lifetime is 19105 hours, which is relatively short, and the emitter used is Pt-X-4 (T d =430℃) has low thermal stability and is difficult to meet the requirements of practical applications. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a high-efficiency, long-life adjustable light-emitting device and its application to solve at least part of the above-mentioned technical problems.

[0006] The present invention discloses a high-efficiency, long-life adjustable light-emitting organic light-emitting device, which includes: an anode and a cathode configured to have a driving voltage on the two electrodes; and a plurality of organic layers between the two electrodes, wherein at least one organic layer is a light-emitting layer, in which two or more host materials are mixed together and a light-emitting material is doped into the layer; the light-emitting material is a platinum complex, and has a monomer emission state and at least one aggregate emission state; there is at least one host material containing a triazine group, and the LUMO energy level of the host material is lower than the LUMO energy level of the light-emitting material or the difference between the LUMO energy levels of the two is less than 0.2eV.

[0007] According to a preferred embodiment, the luminescent material in the luminescent layer is selected to be an efficient phosphorescent Pt(II) emitter coordinated by a tetradentate [O^N^C^N] ligand, wherein the emitter is represented by the following chemical formula:

[0008] In this chemical formula,

[0009] X is independently a 5- or 6-membered heterocyclic ring,

[0010] R1 to R3 are independently selected from the group consisting of hydrogen, halogen, hydroxy, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, mercapto, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl groups,

[0011] R4 is independently selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, sulfonyl, phosphino, and combinations thereof,

[0012] Each pair of adjacent R groups in R1 to R3 is independently one or two independent groups or atoms or is selected to form a 5-6 membered ring,

[0013] R1 to R3 represent mono-, di-, tri-, tetra- or unsubstituted.

[0014] According to a preferred embodiment, the above R4 is independently selected from: dibenzofuranyl or dibenzothienyl.

[0015] According to a preferred embodiment, the luminescent material in the luminescent layer is tetra-Pt-dbf or tetra-Pt-dbt, wherein tetra-Pt-dbf and tetra-Pt-dbt are represented by the following chemical formulas respectively:

[0016] According to a preferred embodiment, the host material in the light-emitting layer can be selected as a combination of a first compound and a second compound.

[0017] Preferably, the first chemical formula of the first compound is represented by:

[0018] Among them, in the first chemical formula,

[0019] X is O or S,

[0020] Z is hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, or substituted or unsubstituted phenyl,

[0021] L 1 and L 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group,

[0022] R a 、R b and R 1 to R 7 and R and R are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group.

[0023] Preferably, the second chemical formula of the second compound is represented by:

[0024] Among them, in the second chemical formula,

[0025] Y 1 and Y 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group,

[0026] Ar 1 and Ar 2 are each independently a substituted or unsubstituted C6 to C20 aryl group or a substituted or unsubstituted C2 to C30 heterocyclic group,

[0027] R c and R 8 to R 13 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C30 heterocyclyl group, a cyano group, or a combination thereof,

[0028] m is 0, 1, or 2.

[0029] According to a preferred embodiment, the first host material in the light-emitting layer is selected as Host1, and the second host material is selected as Host2, so that in the combined host materials, the LUMO energy level of Host1 is lower than the LUMO energy level of the light-emitting material tetra-Pt-dbf or tetra-Pt-dbt, or the difference between the LUMO energy level of Host1 and the LUMO energy level of the light-emitting material is less than 0.2 eV, wherein,

[0030] Host1 is selected from the following compounds:

[0031] Host2 is selected from the following compounds:

[0032] Among them, * is the bonding point,

[0033] *-Y 1 -Ar 1 and *-Y 2 -Ar 2 Is one of the following groups:

[0034] Preferably, the first compound in the light-emitting layer is selected as Host1-1, and the second compound is selected as Host2-1, so that in the combined host material, the LUMO energy level of Host1-1 is lower than or close to the LUMO energy level of the light-emitting material tetra-Pt-dbf or tetra-Pt-dbt, wherein Host1-1 and Host2-1 are respectively represented by the following chemical formulas:

[0035] Energy levels refer to the molecular orbital energy levels of organic molecules, which generally include HOMO and LUMO energy levels. The HOMO energy level refers to the energy level of the highest occupied molecular orbital, equivalent to the valence band in inorganic semiconductors; the LUMO energy level refers to the energy level of the lowest unoccupied molecular orbital, equivalent to the conduction band in inorganic semiconductors. The LUMO energy level of the host material in a typical OLED device is higher than the LUMO energy level of the light-emitting material. However, in the dual host materials used in the present invention, at least one host material has a LUMO energy level lower than or equivalent to the LUMO energy level of the light-emitting material. In particular, when the host materials of the light-emitting layer are a combination of Host1-1 and Host2-1, the LUMO energy level of Host1-1 is configured so that it is lower than or close to the LUMO energy level of the light-emitting material. This protects the excited state of the platinum complex light-emitting material, reduces the excited state electron density or the negative polaron density on the platinum complex molecule, prevents the platinum complex light-emitting molecule from being destroyed, and thus enhances the lifespan of the dimmable OLED device.

[0036] When the host material of the light-emitting layer is a combination of Host1-1 and Host2-1, the HOMO energy levels and LUMO energy levels of the two host materials tetra-Pt-dbf and tetra-Pt-dbt of the present invention and the above two light-emitting materials are shown in the following table:

[0037] According to a preferred embodiment, when the main material of the light-emitting layer is selected as a combination of Host1 and Host2, the doping concentration of the light-emitting material tetra-Pt-dbf is limited to 4wt% to 20wt%, preferably 6wt% to 13wt%, so that the light-emitting device can emit light of different colors at at least two wavelengths; or the doping concentration of the light-emitting material tetra-Pt-dbt is limited to 6wt% to 10wt%, so that the light-emitting device can emit light of different colors at at least two wavelengths.

[0038] The present invention also discloses a high-efficiency, long-life, dimmable organic light-emitting device, comprising: a positive electrode and a negative electrode configured to have a driving voltage on the two electrodes; and a plurality of organic layers between the two electrodes, wherein at least one organic layer is a light-emitting layer, in which two or more host materials are mixed together and a light-emitting material is doped into the layer; the light-emitting material is a platinum complex having a monomer emission state and at least one aggregate emission state; the host material in the light-emitting layer is a combination of SF-BCZ and SF-TRZ, wherein SF-BCZ and SF-TRZ are respectively represented by the following chemical formulas:

[0039] According to a preferred embodiment, in a light-emitting device in which the host material is a combination of SF-BCZ and SF-TRZ, the light-emitting material can be any one of the aforementioned light-emitting materials.

[0040] According to a preferred embodiment, when the main material of the light-emitting layer is selected as a combination of SF-BCZ and SF-TRZ, the doping concentration of the light-emitting material tetra-Pt-dbf or tetra-Pt-dbt is limited to 4wt% to 13wt%, so that the light-emitting device can emit light of different colors at at least two wavelengths.

[0041] According to a preferred embodiment, among the several organic layers between the two electrodes, at least one organic layer is a hole transport layer, at least one organic layer is an electron blocking layer, and at least one organic layer is an electron transport layer; at least one layer attached to the positive electrode is a hole injection layer; and at least one layer attached to the negative electrode is an electron injection layer.

[0042] According to a preferred embodiment, the material of the hole injection layer includes HAT-CN, the material of the hole transport layer includes one or more of TAPC, SF-BCZ, BPBPA, and FSF4A, the material of the electron blocking layer includes one or more of SF-TRZ and ANT-BIZ, the material of the electron transport layer includes DPPyA, ANT-BIZ or one of other materials having the function of transporting electrons, or a structure in which an electron transport material is doped with a Liq material in the electron transport layer, for example, a structure in which ANT-BIZ:Liq 50wt% is used, and the material of the electron injection layer includes one or more of LiF, Liq, and Yb.

[0043] The present invention also discloses an application of a light-emitting layer and a light-emitting device prepared by using an efficient phosphorescent Pt(II) emitter coordinated by a tetradentate [O^N^C^N] ligand as a light-emitting material, and a combination of a first compound and a second compound or a combination of SF-BCZ and SF-TRZ as a main material, wherein the light-emitting device can be used for fixed visual display units, mobile visual display units, lighting units, keyboards, clothing, decorations, clothing accessories, wearable devices, medical monitoring equipment, wall paper, tablet computers, laptop computers, advertising panels, panel display units, household appliances, and office appliances. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a chemical structure diagram of the luminescent materials tetra-Pt-dbf and tetra-Pt-dbt of the present invention;

[0045] FIG2 is a synthesis route of the luminescent material tetra-Pt-dbf according to a preferred embodiment of the present invention;

[0046] FIG3 is a synthesis route of a luminescent material tetra-Pt-dbt according to a preferred embodiment of the present invention;

[0047] Figure 4 (a) to (d) are the specified luminance ranges (100 to 100,000 cd·m) when the doping concentration of tetra-Pt-dbf is 4wt%, 7wt%, 10wt% and 13wt%, respectively. -2 ) is the normalized EL spectrum of the device 1 under different doping concentrations; (e) is the brightness-EQE curve of the device 1 with different doping concentrations; (f) is a schematic diagram of the structure of the device 1 and its energy level diagram;

[0048] Figure 5 shows (a) the X-ray crystal structure and perspective view of tetra-Pt-dbf with hydrogen atoms omitted (thermal ellipsoid probability level: 30%); (b) the UV-visible absorption and emission spectra of tetra-Pt-dbf in toluene at room temperature and in 2-MeTHF at 77K, with a local magnification of the wavelengths 490-540nm; (c) the emission spectra of tetra-Pt-dbf in mCP films with different doping concentrations (2wt%, 5wt%, 8wt%, and 12wt%); (d) the calculated molecular orbital diagrams of the structurally optimized tetra-Pt-dbf monomer and dimer in the T1 excited state, and the EDA calculation results of the [tetra-Pt-dbf]2 dimer based on the X-ray crystal structure.

[0049] Figure 6 (a) to (d) are normalized EL spectra of device 2 when the doping concentration of tetra-Pt-dbf is 4wt%, 7wt%, 10wt% and 13wt% respectively;

[0050] Figure 7 (a) to (c) are normalized EL spectra of device 3 when the doping concentration of tetra-Pt-dbf is 4wt%, 6wt% and 20wt% respectively;

[0051] In Figure 8, (a) normalized EL spectra of device 3 with a doping concentration of 7 wt% tetra-Pt-dbf at 2.4 V, 2.6 V, 2.8 V, 3 V, 4 V, 5 V, 6 V, and 7 V; (b) CIE coordinate shift diagram of device 3 from 2.4 V to 7.0 V; (c) normalized EL spectra of device 3 at 60 mA·cm -2 Relative brightness-working life graph at constant current density; (d) integral area ratio A agg / mon Dependence on the driving voltage of device 3 with tetra-Pt-dbf emitter, where the solid squares represent experimental data, the solid line represents the theoretical fitting results, and the dashed line represents the built-in voltage;

[0052] FIG9 shows (a) a voltage-CIE(x,y) curve of device 3; (b) a brightness-EQE curve of device 3; and (c) an acceleration factor (n) applicable to device 3.

[0053] FIG10 shows the color change of device 3 at the initial brightness and when it decays to 90% of the initial brightness under constant current conditions, where (a) initial brightness L0 = 20290 cd m -2 (b) Initial luminance L0 = 11063 cd m -2 ;

[0054] FIG11 shows the color coordinate change curves of the device 3 when it is operated at different constant voltages for 100 minutes, where (a) is 2.6 V; (b) is 3.0 V; (c) is 4.0 V; and (d) is 6.0 V.

[0055] FIG12 (a) to (d) are electroluminescence images of device 4 when the doping concentration of tetra-Pt-dbt is 6 wt%, 7 wt%, 8 wt% and 10 wt%, respectively;

[0056] FIG13 depicts the chemical structures of the primary organic materials used to construct the light-emitting devices described herein;

[0057] FIG14 is a cyclic voltammogram of tetra-Pt-dbf in DMF;

[0058] FIG15 is a TGA thermogram of tetra-Pt-dbf (heating rate is 10° C. / min);

[0059] Figure 16 shows the Pt-X-4 molecule in toluene (2x10 -5 M) (a) UV-visible absorption spectra and (b) normalized electroluminescence spectra at different time periods;

[0060] Figure 17 shows the tetra-Pt-dbf molecule in toluene (2x10 -5 M) (a) UV-visible absorption spectra and (b) normalized electroluminescence spectra at different time periods. DETAILED DESCRIPTION

[0061] The following is a detailed description with reference to the accompanying drawings.

[0062] According to a preferred embodiment, the present invention discloses a high-efficiency, long-life dimmable organic light-emitting device, which achieves stability in manufacturing and operation of the light-emitting device through a stable device structure and a stable emitter, so that the light-emitting device can meet the practical application requirements of human-computer interaction terminals or wearable biomedical devices.

[0063] In one or more embodiments, the emitter used as a dopant in the light-emitting layer is a metal complex having a tetragonal planar chemical structure. Preferably, the metal complex is a platinum complex. In one or more embodiments, the emitter is a compound having a Pt[O^N^C^N] structure.

[0064] The present invention discloses a series of efficient phosphorescent Pt(II) emitters coordinated by tetradentate [O^N^C^N] ligands. In a preferred embodiment, based on the luminescence of such Pt(II) complexes, a light-emitting device can achieve a high EQE of up to 30.2%. Preferably, tetra-Pt-dbf and tetra-Pt-dbt (as shown in FIG1 ) of the present invention have the potential to be used as single luminescent dopants in the fabrication of voltage-dependent, color-tunable light-emitting devices, because Pt[O^N^C^N] complexes have excellent electroluminescent (EL) properties in both monomeric and aggregated states. FIG2 and FIG3 are synthetic route diagrams of tetra-Pt-dbf and tetra-Pt-dbt of the present invention, respectively.

[0065] Preferably, tetra-Pt-dbf and tetra-Pt-dbt exhibit short τ and excellent PLQY in both the monomeric and aggregated states, enabling their use as single emitters in CT-OLEDs. Therefore, the present invention discloses stable, color-tunable OLED devices or light-emitting devices utilizing single emitters of tetra-Pt-dbf or tetra-Pt-dbt. Furthermore, such devices or light-emitting devices can employ a structure in which dual host materials dope the single emitter. By precisely controlling the doping concentration, CT-OLED devices can be achieved with high efficiency, a wide dimming range, and an extremely long lifetime.

[0066] Example 1

[0067] According to a preferred embodiment, this embodiment discloses a light-emitting device having the following device structure, a schematic diagram of the structure and an energy level diagram of which are shown in FIG4f :

[0068] Device 1: ITO / HAT-CN (5nm) / TAPC (30nm) / SF-BCZ (10nm) / SF-BCZ:SF-TRZ:tetra-Pt-dbf (xwt%) (30nm) / SF-TRZ (10nm) / DPPyA (30nm) / LiF (1.2nm) / Al (150nm),

[0069] The device comprises ITO as a transparent anode, HAT-CN as a hole injection layer, TAPC as a first hole transport layer, SF-BCZ as a second hole transport layer, responsible for transporting holes and preventing exciton quenching at the hole-host interface, SF-TRZ as an electron blocking layer, preventing electrons from leaving the luminescent layer, DPPyA as an electron transport layer, LiF as an electron injection layer, and Al as an aluminum electrode, serving as the device's cathode. In the emissive layer (EML), SF-BCZ serves as host material 1, SF-TRZ as host material 2, and tetra-Pt-dbf as the luminescent material. "x wt%" represents the doping concentration of the luminescent material, ranging from 4 wt% to 13 wt%, and more specifically, 4 wt%, 7 wt%, 10 wt%, and 13 wt%. Here, tetra-Pt-dbf is the sole emitter.

[0070] As shown in Figure 4, the color-tunable EL characteristics of device 1 with different doping concentrations of the light-emitting materials can be seen. Specifically, at a low doping concentration of 4 wt%, the EL spectrum (shown in Figure 4a) shows a single peak at 525 nm, which can be classified as the monomer emission of tetra-Pt-dbf compared with the PL spectrum in Figure 5b. As the brightness increases from 100 cd·m -2 Increased to 100,000 cd·m -2 , these EL spectra remain consistent, keeping the CIE coordinates around (0.342, 0.618), with a deviation of (±0.01, ±0.01). However, as shown in Figures 4b to 4d, as the dopant concentration increases from 7wt% to 13wt%, a new emission peak appears near 670nm, which can be classified as the aggregated emission of tetra-Pt-dbf compared with the PL spectrum in Figure 5b. As can be seen from Figure 4d, the color-tunable phenomenon can be clearly observed in device 1 with a doping concentration of 13wt%. Combined with Table 1, it can be seen that the CIE coordinates move from (0.479, 0.508) at 2.8V to (0.449, 0.533) at 7V. This shows that the device 1 of the present invention is capable of emitting light of different colors at two wavelengths to achieve color tunability.

[0071] Table 1 Partial performance of various OLED devices when doped with different concentrations of tetra-Pt-dbf

[0072] a CIE comes from the French Commission Internationale de L'Eclairage, which refers to the International Commission on Illumination. The corresponding data in the table are obtained with reference to the chromaticity coordinate diagram specified by CIE in 1931.

[0073] bThe initial brightness is 1000 nits (1000 cd m -2 ) when the device brightness decays to 90% of the initial brightness.

[0074] c The initial brightness is 100 nits (100 cd m -2 ) when the device brightness decays to 90% of the initial brightness.

[0075] As shown in FIG4e , the device 1 with different doping concentrations is in the range of 1000 to 10000 cd·m -2 The device with 4 wt% tetra-Pt-dbf exhibits the highest EQE. max , is 30.2%. Even at 1000cd·m -2 and 10000 cd·m -2 At high brightness, the EQE of the device is maintained at 30.0% and 27.8% respectively. Its maximum brightness is as high as 148300cd·m -2 (As shown in Table 1). Meanwhile, the device containing 13 wt% tetra-Pt-dbf not only has a wide color tuning range, but also exhibits an EQE as high as 28.1%. max , and respectively at 1000 cd·m -2 and 10000 cd·m -2 The low efficiency roll-off (EQE 1000 EQE 10000 is 25.0%).

[0076] It can be seen from this that this CT-OLED is one of the most efficient CT-OLEDs, EQE max The EL efficiency reaches approximately 30%, surpassing most existing CT-OLEDs. This high EL efficiency can be attributed to the high PLQY of the emitter tetra-Pt-dbf in both the monomeric and aggregated states. Furthermore, the well-aligned energy levels from the ETL to the EML reduce the energy barrier and prevent associated quenching. The short excited-state lifetime and high thermal stability of tetra-Pt-dbf also help suppress triplet-related annihilation or thermal degradation, thereby suppressing efficiency roll-off at high brightness.

[0077] Therefore, the device 1 in this embodiment can not only emit light of different colors at two wavelengths to achieve color tunability, but also has a high EQE max , making its EL efficiency higher than the existing CT-OLED.

[0078] Example 2

[0079] According to a preferred embodiment, this embodiment discloses a light emitting device having the following device structure:

[0080] Device 2: ITO / HAT-CN(5nm) / BPBPA(120nm) / FSF4A(10nm) / SF-BCZ:SF-TRZ:tetra-Pt-dbf(ywt%)(20nm) / ANT-BIZ(10nm) / ANT-BIZ:Liq 50wt%(40nm) / Liq(1.2nm) / Al(100nm),

[0081] The device comprises ITO as a transparent anode, HAT-CN as a hole injection layer, BPBPA as a first hole transport layer, FSF4A as a second hole transport layer, responsible for transporting holes and preventing exciton quenching at the hole-host interface, ANT-BIZ as a first electron transport layer, responsible for transporting electrons and blocking holes from entering the non-emissive region, ANT-BIZ:Liq 50 wt% as a second electron transport layer, Liq as an electron injection layer, and Al as an aluminum electrode, serving as the device's cathode. In the emitting layer (EML), SF-BCZ is the host material 1, SF-TRZ is the host material 2, and tetra-Pt-dbf is the luminescent material. "y wt%" represents the doping concentration of the luminescent material, ranging from 4 wt% to 13 wt%, and more specifically, 4 wt%, 7 wt%, 10 wt%, and 13 wt%. Here, tetra-Pt-dbf is a single emitter.

[0082] Preferably, as shown in FIG6 and Table 1, the device 2 exhibits a color-tunable EL spectrum, good efficiency and operational stability. EQE of the device 2 with different doping concentrations max All above 15%, LT 90 When L0 is 100 cd·m -2 Among these devices, assuming an acceleration factor n of 1.75, the device with a doping concentration of 7 wt% has an L0 of 100 cd·m -2 LT 90 The longest is about 77772 hours. When the doping concentration is increased to 10wt%, a larger color range and longer service life can be achieved, and its CIE coordinates move from (0.476, 0.510) at 2.8V to (0.434, 0.541) at 7V. 90 As long as 37,789 hours.

[0083] The device 2 of this embodiment uses SF-BCZ and SF-TRZ as the main materials and tetra-Pt-dbf as the luminescent material. When the doping concentration is 4wt% to 13wt%, the light emitting device can emit light of different colors at two wavelengths, and its device life LT 90@100nits The lifespan is approximately between 37,000 hours and 77,000 hours, which is significantly improved compared to conventional color-tunable OLED devices.

[0084] Example 3

[0085] According to a preferred embodiment, in order to further improve the service life of the CT-OLED, this embodiment discloses a light-emitting device having the following device structure:

[0086] Device 3: ITO / HAT-CN (5 nm) / BPBPA:HAT-CN 3 wt% (10 nm) / BPBPA (50 nm) / FSF4A (10 nm) / Host1-1:Host2-1:tetra-Pt-dbf (z wt%) (20 nm) / ET:Liq 50 wt% (40 nm) / Yb (1 nm) / Ag (100 nm),

[0087] Among them, ITO is the transparent anode; HAT-CN is the hole injection layer; BPBPA:HAT-CN is the first hole transport layer; BPBPA is the second hole transport layer; FSF4A is the electron blocking layer, used to prevent electrons from leaving the light-emitting layer; Host1-1+Host2-1 constitute the light-emitting layer, which is also doped with a certain proportion of the light-emitting material tetra-Pt-dbf; and the electron transport layer uses a structure in which the electron transport material doped with Liq material, such as ET:Liq 50wt%, where the electron transport material can also be selected from one of ANT-BIZ, DPPyA, etc.; Yb is used as the electron injection layer, and Ag is used as the cathode. In the light-emitting layer (EML), Host1-1 is the host material 1, Host2-1 is the host material 2, tetra-Pt-dbf is the light-emitting material, and z wt% represents the doping concentration of the light-emitting material, where z wt% can be 4wt% to 20wt%, and can be further specifically a doping concentration of 4wt%, 6wt%, 7wt%, and 20wt%; here, tetra-Pt-dbf is a single emitter.

[0088] Preferably, as shown in Figure 7, for device 3, when the doping concentration is 4wt%, the device has no dimming effect. When the doping concentration of the luminescent material is increased to 6wt%, the device begins to show obvious spectral changes. When the doping concentration is increased to 20wt%, the device basically emits concentrated deep red light, and the dimming effect basically disappears. Therefore, the doping concentration of the luminescent material can be selected from 4wt% to 20wt%, and more preferably from 6wt% to 13wt%.

[0089] Figure 8a shows the different EL spectra of device 3 with a doping concentration of 7wt% at driving voltages of 2.4V, 2.6V, 2.8V, 3V, 4V, 5V, 6V, and 7V. At low voltages of 2.4 to 2.6V, the aggregated emission of tetra-Pt-dbf (peak value is about 670nm) is dominant, and as the voltage increases, the stably enhanced monomer emission (peak value is about 525nm) gradually becomes dominant. As shown in Table 1 and Figure 8b, device 3 has a wide color adjustment range, and the CIE coordinates move from (0.510, 0.475) at 2.4V to (0.379, 0.584) at 7.0V. As shown in Figures 8c and 9, when L0 is 20290cd·m -2 When its working life LT 90 The degradation acceleration factor n calculated by the exponential decay model is 1.7485, and the brightness is 10000 cd·m -2 , 1000cd·m -2 and 100 cd·m -2 Case LT 90 The lifetimes are approximately 166 hours, 9,288 hours, and 520,536 hours, respectively. These lifetimes are more than 20 times longer than the most advanced existing CT-OLEDs and are even comparable to the lifetimes of most existing stable single-color OLED devices. This demonstrates that the color-tunable light-emitting device of the present invention, which utilizes a light-emitting layer comprising the aforementioned host material and light-emitting material combination, overcomes the technical bottleneck of CT-OLED lifetimes being significantly lower than that of single-color OLEDs, enabling the lifespan of CT-OLEDs to reach or even exceed that of single-color OLEDs. This addresses the technical bias in the art of not considering the impact of intermolecular π-π stacking interactions on device lifetime and stability during the material combination process when combining host and light-emitting materials. This opens up a new research and development approach for significantly extending the lifetime of color-tunable light-emitting devices by utilizing the π-π stacking interactions in light-emitting materials and doping them with specific host material combinations.

[0090] As shown in Figure 10 and Table 2, at 30 or 60 mA·cm -2Under the constant driving current density of , the driving voltage of device 3 only shows a slight increase of 0.6V or 0.4V, resulting in the offset of CIEx and CIEy of 0.008% or 0.004% and 0.006% or 0.004%, respectively, which is negligible, indicating that the stability of device 3 is excellent. Further, Figure 11 shows the color coordinate change curve of the luminescence of device 3 of the present invention after working at a constant voltage for 100 minutes. It can be seen from the figure that the color coordinates of device 3 have basically not changed, indicating that the stability of the device is excellent. However, the existing CT-OLED usually changes its luminous color after working at a constant current or voltage for a long time, and it is difficult to achieve the stability of the light-emitting device of the present invention. Therefore, the light-emitting device of the present invention has excellent practical value. On the other hand, considering the estimated service life of device 3 (LT 90@100nits =520536 hours), at 100 cd m -2 When the device 3 is actually used at low brightness, no significant device degradation will occur. Therefore, after long-term use, the color tunable performance of the device 3 of the present invention is basically not affected.

[0091] Table 2 Changes in voltage and color coordinates CIE before and after device decay for device 3 under constant current

[0092] Compared with the prior art CN116602071A which uses Pt-X-4 as the emitter CT-OLED (LT 90@100nits =19105 hours), the CT-OLED of the present invention using tetra-Pt-dbf as the emitter not only has a service life far exceeding that of the prior art CT-OLED by dozens of times, but also shows more excellent device stability. The excellent operational stability of the CT-OLED of the present invention can be attributed to the short excited state lifetime of tetra-Pt-dbf in the monomeric and aggregated states (τ<2us). Due to the "heavy atom effect", phosphorescent metal organic emitters usually have a short triplet excited state lifetime, which promotes rapid radiative decay from the triplet excited state to the ground state. This greatly suppresses triplet-related annihilation, not only reducing the efficiency roll-off at high current density, but also extending the device life. Both the monomeric emission and the aggregated emission of tetra-Pt-dbf have short excited state lifetimes, which is different from other complexes that have short excited state lifetimes only in the monomeric or aggregated states.

[0093] To better explain this excellent color tunable mechanism, the “capture and energy transfer model” can be applied to simulate the experimental data, where the model can be expressed as follows:

[0094] The above formula is derived for single-layer OLED and can be applied to multi-layer OLED to explain color-tunable OLED. Unlike previous literature reports that only use the intensity ratio of different emission bands, the integrated area ratio A is used in this invention. agg / mon (obtained by "Guass" fitting) to describe the emission ratio q(U) in the above formula. This method is adopted because the full width at half maximum (FWHM) of the aggregate emission band is larger than that of the monomer emission band. If q(U) is described by the intensity ratio, it will lead to serious deviations in the simulation process. In the above formula, D is the diffusion coefficient of the captured electron, μ is the mobility of the carrier, d is the thickness of the EML, and L T is the average diffusion distance before the carriers reach the capture center, U is the driving voltage, and U0 is the built-in electron field. Furthermore, D / μ is the Einstein relationship that describes the ratio between diffusion rate and mobility. By using the above equation to fit the experimental data, the curve fit matches the experimental data, and the correlation coefficient R 2 The experimental data are highly consistent with the fitted curve, indicating that this color tunability can be attributed to a competition between charge trapping and direct energy transfer mechanisms.

[0095] Example 4

[0096] According to a preferred embodiment, this embodiment discloses a light emitting device having the following device structure:

[0097] Device 4: ITO / HAT-CN (5 nm) / BPBPA:HAT-CN 3 wt% (10 nm) / BPBPA (50 nm) / FSF4A (10 nm) / Host1-1:Host2-1:tetra-Pt-dbt (a wt%) (20 nm) / ET:Liq 50 wt% (40 nm) / Yb (1 nm) / Ag (100 nm),

[0098] Among them, ITO is the transparent anode; HAT-CN is the hole injection layer; BPBPA:HAT-CN is the first hole transport layer; BPBPA is the second hole transport layer; FSF4A is the electron blocking layer, used to prevent electrons from leaving the light-emitting layer; Host1-1+Host2-1 constitute the light-emitting layer, which is also doped with a certain proportion of the light-emitting material tetra-Pt-dbt; and the electron transport layer uses a structure in which the electron transport material doped with Liq material, such as ET:Liq 50wt%, where the electron transport material can also be selected from one of ANT-BIZ, DPPyA, etc.; Yb is used as the electron injection layer, and Ag is used as the cathode. In the light-emitting layer (EML), Host1-1 is host material 1, Host2-1 is host material 2, tetra-Pt-dbt is the light-emitting material, and a wt% represents the doping concentration of the light-emitting material, where a wt% can be 6wt% to 10wt%, and can be further specifically a doping concentration of 6wt%, 7wt%, 8wt%, and 10wt%; here, tetra-Pt-dbt is a single emitter.

[0099] FIG12 shows the electroluminescence graphs of the device 4 doped with different concentrations of tetra-Pt-dbt at driving voltages of 6wt%, 7wt%, 8wt% and 10wt% respectively. When the doping concentration of the luminescent material tetra-Pt-dbt is in the range of 6wt% to 10wt%, the device 4 can emit light of different colors at two wavelengths at a driving voltage of 2.6 to 10V to achieve color tunability. Therefore, the CT-OLED of the present invention uses a single luminescent material tetra-Pt-dbf or tetra-Pt-dbt to simultaneously achieve monomer (high energy band) emission and aggregate (low energy band) emission, and has a short excited state lifetime, thereby extending the service life of the light-emitting device. Taking tetra-Pt-dbf as an example, compared with the emitter Pt-X-4 (T d =430℃), the tetra-Pt-dbf of the present invention has higher thermal stability (T d =508°C). Furthermore, due to strong intermolecular π-π stacking interactions, the dimer [tetra-Pt-dbf]2 exhibits a higher intermolecular bond energy (-52.0 kcal / mol), for example, higher than the -44.2 kcal / mol of Pt-X-4. This indicates that the tetra-Pt-dbf aggregates possess high chemical stability, which can inhibit their decomposition in OLED devices. This reduces thermal degradation and improves the stability of devices fabricated using tetra-Pt-dbf. Furthermore, the same applies to tetra-Pt-dbt.

[0100] Furthermore, unlike existing CT-OLEDs that use multiple emitters, the present invention's single-emitter CT-OLEDs essentially avoid the "color aging problem" and eliminate quenching between different dopants in the EML, thereby extending the lifetime. The present invention's CT-OLEDs, doped with a single tetra-Pt-dbf or tetra-Pt-dbt emitter, exhibit a wide color tuning range, high EQE, low efficiency roll-off, and excellent operational stability. This suggests that CT-OLEDs using planar luminescent Pt(II) complexes as single emitters have broad application prospects, such as in smart lighting, decoration, and wearable biomedical sensors.

[0101] Example 5

[0102] Table 3 shows relevant performance data of the light-emitting device of the present invention when using different combinations of host materials.

[0103] Table 3 Comparison of device performance of light-emitting devices using different combinations of host materials and doped with the same luminescent material tetra-Pt-dbf

[0104] Preferably, the chemical structures of Host1-2 to Host1-5 are as follows:

[0105] Preferably, the chemical formulas of Host2-2 and Host2-3 are as follows:

[0106] Experimental part

[0107] Materials: HAT-CN, TAPC, ANT-BIZ, Al, Yb, Ag, and LiF were purchased from Luminescence Technology Corp., and BPBPA, DPPyA, SF-BCZ, SF-TRZ, Host1, and Host2 were purchased from PURI Materials. All of these materials were used as received without further purification. Tetra-Pt-dbf was synthesized and purified by gradient sublimation before use. The chemical structures of all organic materials are shown in Figure 13.

[0108] PLQY measurements and electrochemical measurements: The steady-state emission spectra of the complexes in solution, glass, and solid were studied using a Horiba Fluorolog-3 spectrophotometer. The emission of the glassy state was measured in 2-methyltetrahydrofuran at 77 K. The solutions used for the photophysical studies were degassed using a high vacuum line in a two-chamber cell and subjected to five freeze-pump-thaw cycles. The glassy and solid samples were recorded in quartz tubes (4 mm inner diameter) placed in a liquid nitrogen dewar with a quartz window. The emission quantum yields of the samples in thin films and solutions were measured using a Hamamatsu C11347 Quantaurus-QY absolute PL quantum yield measurement system. The films were prepared by drop casting from chlorobenzene solutions containing PMMA complexes (2 wt% to 12 wt%) and the solvent was evaporated at 80°C to obtain translucent films. The emission lifetime measurements were performed on a Quanta Ray GCR 150-10 pulsed Nd:YAG laser system. The errors of λ value (±1 nm), τ value (±10%) and Φ value (±10%) were estimated. Cyclic voltammetry measurements were performed on a CHI620E electrochemical analyzer / workstation with a conventional three-chamber cell. A 0.1 M (nBu4N)-PF6 solution in DMF was used as the supporting electrolyte for the electrochemical measurements. All solutions used in the electrochemical measurements were degassed by argon bubbling, and the measurements were performed at room temperature. A saturated calomel electrode was used as the reference electrode, a glassy carbon electrode was used as the working electrode, a platinum wire was used as the counter electrode, and ferrocene was used as the internal reference.

[0109] Device Fabrication and Characterization: Indium tin oxide (ITO)-coated glass with a sheet resistance of 10 Ω / sq was used as the anode substrate. The patterned ITO substrate was cleaned with detergent, rinsed with deionized water, acetone, and isopropyl alcohol, and then dried in a cleanroom oven for 1 hour. The glass slide was then treated in a UV ozone chamber for 5 minutes. The OLEDs were fabricated in a Kurt J. Lesker SPECTROS vacuum deposition system with a base pressure of 10 -8 In a vacuum chamber, organic materials have a speed of 0.02 to 0.1 nm·s -1 The doping process of the light-emitting layer is realized by co-deposition technology. LiF (or Liq) and Yb are deposited at a rate of 0.03nm·s -1 Al or Ag is thermally deposited at a rate of 0.2 nm·s by the metal source of the vacuum deposition system. -1 The film thickness was determined in situ using a calibrated oscillating quartz crystal sensor.

[0110] EL spectra, JLV characteristics, CIE coordinates, CRI, EQE, CE, and PE were measured using a Keithley 2400 source meter and an absolute external quantum efficiency measurement system (C9920-12, Hamamatsu Photonics). EL distribution was measured using an angle-dependent device test system (C9920-11, Hamamatsu Photonics). The OLED was encapsulated in a 200nm thick Al2O3 film deposited by atomic layer deposition (ALD) on a Kurt J. Lesker SPECTROS ALD system.

[0111] Mass spectra (ESI) were recorded on a Bruker Impact IIQT mass spectrometer. Elemental analyses were performed at the Institute of Chemistry, Chinese Academy of Sciences.

[0112] Some experimental results are shown below:

[0113] Preferably, the X-ray crystal structure of tetra-Pt-dbf is shown in FIG5a , and the selected bond lengths, bond angles, and crystallographic data are summarized in Tables 4 and 5 . Two tetra-Pt-dbf molecules are arranged in a head-to-head orientation with a Pt-Pt distance of In the crystal structure, intermolecular π-π interactions can be observed between each pair of tetra-Pt-dbf molecules, and the intermolecular distance is approximately

[0114] Table 4 Some bond lengths of tetra-Pt-dbf and bond angles ( o )

[0115] Table 5 Crystallographic data of tetra-Pt-dbf

[0116] Preferably, the electrochemical properties of tetra-Pt-dbf were investigated by cyclic voltammetry (CV) in N,N-dimethylformamide (DMF), and the electrochemical data are shown in FIG14 . For this complex, at -1.58 V (E red ) was observed at 0.79 V (E ox ) and an irreversible oxidation wave was observed. Both the reduction peak and the irreversible oxidation wave are attributed to the ligand-centered reaction of the O^N^C^N molecule. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the complex were estimated based on the onset oxidation and reduction potentials of -5.12 eV and -2.74 eV, respectively. The photophysical data for tetra-Pt-dbf are shown in Table 6.

[0117] Table 6 Photophysical data of tetra-Pt-dbf

[0118] Figure 5b depicts the UV-visible absorption spectrum of the complex in toluene solution. The strong absorption band at wavelengths below 320 nm (ε>4×10 4 dm 3 ·mol -1 cm -1 ) corresponds to the π-π of the O^N^C^N ligand * Transition. A relatively weak absorption band (ε=(0.076–1.2)×10 4 dm 3 ·mol -1 cm -1 ) can be attributed to mixed singlet intra-ligand charge transfer (ILCT) and singlet metal-to-ligand charge transfer (MLCT) transitions. tetra-Pt-dbf exhibits a strong yellow-green color (λ max =529nm) emission, the emission lifetime τ is 2.44us, and the emission quantum yield is as high as 0.82. The unstructured yellow-green emission band (λ max =529 nm) indicates that the emission excited state has a mixed MLCT / ILCT spectrum.

[0119] Different concentrations of tetra-Pt-dbf were doped into mCP films to study the solid-state photophysical properties of the complex. As shown in Figure 5c, all films exhibited strong emission with a maximum range of 523 nm (2 wt%) to 526 nm (12 wt%), which is attributed to the monomer emission of tetra-Pt-dbf. However, as the doping concentration increased from 2 wt% to 12 wt%, another low-energy emission (λ max =657-665nm), which is attributed to triplet metal-metal-ligand charge transfer (MMLCT) emission in the aggregated state. The tetra-Pt-dbf / mCP film exhibits a high PLQY (e.g., 0.66 at a doping concentration of 12wt% and 0.87 at a doping concentration of 2wt%), and a shorter τ of the emission band (e.g., τ = 2.10-1.34µs for the 523-526nm emission band and τ = 1.61-1.13µs for the 657-667nm emission band), demonstrating excellent photoluminescence performance in both the monomeric and aggregated states.

[0120] Since the stability of solid-state complexes is closely related to intermolecular interactions, the present invention performs energy decomposition analysis (EDA) on the dimer [tetra-Pt-dbf]2. The EDA results show that the dimer [tetra-Pt-dbf]2 has a strong intermolecular bonding energy of -52.0 kcal / mol (as shown in FIG5d). The present invention optimizes the ground state S0 structure and the lowest triplet excited state T1 structure of the dimer [tetra-Pt-dbf]2. Calculations on the dimer [tetra-Pt-dbf]2 show that the Pt-Pt distance in the T1 state is and The molecular orbital (MO) diagrams of the T1-optimized structure of monomer tetra-Pt-dbf and dimer [tetra-Pt-dbf]2 are shown in Figure 5d. For monomer tetra-Pt-dbf, Pt-5dz 2 The orbital is HOMO-5. After dimerization, the short Pt-Pt contact distance of the dimer [tetra-Pt-dbf]2 in the T1 state leads to the two Pt-5dz 2 There is a large energy split between the orbitals. Such a large energy split will 2 ) orbital is elevated to the HOMO in the [tetra-Pt-dbf]2 dimer, while the LUMO is primarily localized on the ligand. Therefore, the excited state of the tetra-Pt-dbf aggregate is essentially a metal-metal-ligand charge transfer (MMLCT) process. Calculated emission energy from the [tetra-Pt-dbf]2 dimer in the T1 state is 1.67 eV, which is consistent with the experimentally observed emission energy of 1.77 eV in OLED devices.

[0121] Preferably, the present invention studies the thermal stability of tetra-Pt-dbf by thermogravimetric analysis, and the decomposition temperature T d is 508°C (as shown in Figure 15), where T d Defined as 5 wt% loss, Figure 15 shows that tetra-Pt-dbf has excellent thermal stability. Compared with the single emitter Pt-X-4 (T d =430 °C), tetra-Pt-dbf has a higher decomposition temperature than that of tetra-Pt-dbf, indicating that dibenzo[b,d]furan substitution can enhance the thermal stability of Pt emitters.

[0122] Preferably, the present invention further compares the molecular stability of tetra-Pt-dbf and existing Pt-X-4 under continuous irradiation with a 455nm LED (25W power) in toluene, obtaining UV-visible absorption and emission spectra as shown in Figures 16 and 17 . As can be seen from the figures, the UV-visible absorption spectrum of tetra-Pt-dbf remains nearly unchanged over 420 minutes, while the UV-visible absorption spectrum of Pt-X-4 exhibits significant changes. The PL spectrum of tetra-Pt-dbf at 0 minutes and 420 minutes also remains unchanged, while the PL spectrum of Pt-X-4 at 0 minutes and 420 minutes also exhibits significant changes. This demonstrates that the tetra-Pt-dbf selected in the present invention exhibits superior molecular stability, resulting in improved stability in OLED devices fabricated using this complex. Similarly, OLED devices fabricated using tetra-Pt-dbf can also exhibit improved stability.

[0123] As shown in Table 6, tetra-Pt-dbf has a higher PLQY, which ranges from 0.66 to 0.87; while the PLQY of the existing Pt-X-4 is much lower, specifically, it is all below 0.60. This is because the dibenzofuran unit of tetra-Pt-dbf can make the tetra-Pt-dbf molecular aggregate have a relatively rigid structure, thereby reducing the non-radiative decay of the 3MMLCT excited state of tetra-Pt-dbf. Furthermore, the dibenzothiophene unit of tetra-Pt-dbt may also have similar properties that reduce the non-radiative decay of the 3MMLCT excited state of tetra-Pt-dbt. Therefore, the light-emitting device of the present invention using tetra-Pt-dbf or tetra-Pt-dbt as the light-emitting material can have an ultra-long life while also having an EQE higher than the existing Pt-X-4 CT-OLED. max Table 7 is a comparison table of the CT-OLED of the present invention and some existing CT-OLEDs.

[0124] Table 7 Comparison of the CT-OLED of the present invention and some existing CT-OLEDs

[0125] Note: The data of CT-OLED device No. 1 is the data of the present invention, and the data of CT-OLED devices No. 2 to No. 10 are taken from the following documents:

[0126] a)M.Mao,T.-L.Lam,W.-P.To,X.Lao,W.Liu,S.Xu,G.Cheng,C.-M.Che,Adv.Mater.2021,33,2004873;

[0127] b)G.Cheng,KTChan,W.-P.To,C.-M.Che,Adv.Mater.2014,26,2540-2546;

[0128] c)C.Zhang,D.Zhang,Z.Bin,Z.Liu,Y.Zhang,H.Lee,JHKwon,L.Duan,Adv.Mater.2021,2103102;

[0129] d)S.Ying,Y.Wu,Q.Sun,Y.Dai,D.Yang,X.Qiao,J.Chen,D.Ma,Appl.Phys.Lett.2019,114,033501;

[0130] e)JHKoo,S.Jeong,HJShim,D.Son,J.Kim,DCKim,S.Choi,J.-I.Hong,D.-H.Kim,ACS nano.2017,11,10032-10041;

[0131] f)S.Liu,R.Wu,J.Huang,J.Yu,Appl.Phys.Lett.2013,103,133307;

[0132] g)M. T.Schwab,M.Kliem,S.Hofmann,K.Leo,MCGather,Light:Sci.&Appl.2015,4,DOI:10.1038 / lsa.2015.20;

[0133] h)G.Mu,T.Rao,Y.Qi,S.Ma,Q.Hao,M.Chen,X.Tang,Adv.Funct.Mater.2023,2301280;

[0134] i)W.Sun,S.Jiao,S.Li,D.Zhang,X.Xia,L.Zhou,Adv.Optical Mater.2023,11,2300902.

[0135] It should be noted that the above specific embodiments are exemplary, and those skilled in the art may come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of disclosure of the present invention and fall within the scope of protection of the present invention.

Claims

1. A high-efficiency, long-life, dimmable organic light-emitting device, characterized in that: It includes: a light-emitting layer in which two or more host materials are mixed together and a light-emitting material is doped into the layer; Wherein, the luminescent material is a platinum complex, and it has monomer emission state luminescence and at least one aggregate emission state luminescence; There is at least one host material containing a triazine group, and the LUMO energy level of the host material is lower than the LUMO energy level of the light-emitting material, or the difference between the LUMO energy levels of the two is less than 0.2 eV.

2. The light emitting device according to claim 1, wherein The luminescent material in the luminescent layer is selected to be an efficient phosphorescent Pt(II) emitter coordinated by a tetradentate [O^N^C^N] ligand, wherein the emitter is represented by the following chemical formula: In this chemical formula, X is independently a 5- or 6-membered heterocyclic ring, R1 to R3 are independently selected from the group consisting of hydrogen, halogen, hydroxy, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, mercapto, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl groups, R4 is independently selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, sulfonyl, phosphino, and combinations thereof, Each pair of adjacent R groups in R1 to R3 is independently one or two independent groups or atoms or is selected to form a 5-6 membered ring, R1 to R3 represent mono-, di-, tri-, tetra- or unsubstituted.

3. The light emitting device according to claim 1 or 2, characterized in that: R4 is independently selected from: dibenzofuranyl or dibenzothienyl.

4. The light emitting device according to any one of claims 1 to 3, characterized in that: The luminescent material in the luminescent layer is tetra-Pt-dbf or tetra-Pt-dbt, wherein tetra-Pt-dbf and tetra-Pt-dbt are represented by the following chemical formulas respectively:

5. The light emitting device according to any one of claims 1 to 4, characterized in that: The host material in the light-emitting layer can be selected from a combination of a first compound and a second compound, wherein: The first chemical formula of the first compound is represented by: Among them, in the first chemical formula, X is O or S, Z is hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, or substituted or unsubstituted phenyl, L 1 and L 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group, R a 、R b and R 1 to R 7 are each independently hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, or substituted or unsubstituted C6 to C20 aryl; The second chemical formula of the second compound is represented by: Among them, in the second chemical formula, Y 1 and Y 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group, Ar 1 and Ar 2 are each independently a substituted or unsubstituted C6 to C20 aryl group or a substituted or unsubstituted C2 to C30 heterocyclic group, R c and R 8 to R 13 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C30 heterocyclyl group, a cyano group, or a combination thereof, m is 0, 1, or 2.

6. The light emitting device according to any one of claims 1 to 5, characterized in that: The first host material in the light-emitting layer is selected as Host1, and the second host material is selected as Host2, so that in the combined host materials, the LUMO energy level of Host1 is lower than the LUMO energy level of the light-emitting material tetra-Pt-dbf or tetra-Pt-dbt, or the difference between the LUMO energy level of Host1 and the light-emitting material is less than 0.2 eV. in, Host1 is selected from the following compounds: Host2 is selected from the following compounds: Among them, * is the bonding point, *-Y 1 -Ar 1 and *-Y 2 -Ar 2 Is one of the following groups:

7. The light emitting device according to any one of claims 1 to 6, characterized in that: Host1 uses Host1-1, and Host2 uses Host2-1. Their chemical structures are:

8. A high-efficiency, long-life, dimmable organic light-emitting device, characterized in that: It includes: a light-emitting layer in which two or more host materials are mixed together and a light-emitting material is doped into the layer; Wherein, the luminescent material is a platinum complex, and it has monomer emission state luminescence and at least one aggregate emission state luminescence; The host material in the light-emitting layer is a combination of SF-BCZ and SF-TRZ, wherein SF-BCZ and SF-TRZ are represented by the following chemical formulas respectively:

9. The light emitting device according to claim 8, characterized in that The luminescent material in the luminescent layer is selected to be an efficient phosphorescent Pt(II) emitter coordinated by a tetradentate [O^N^C^N] ligand, wherein the emitter is represented by the following chemical formula: In this chemical formula, X is independently a 5- or 6-membered heterocyclic ring, R1 to R3 are independently selected from the group consisting of hydrogen, halogen, hydroxy, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, mercapto, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl groups, R4 is independently selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, sulfonyl, phosphino, and combinations thereof, Each pair of adjacent R groups in R1 to R3 is independently one or two independent groups or atoms or is selected to form a 5-6 membered ring, R1 to R3 represent mono-, di-, tri-, tetra- or unsubstituted.

10. The light emitting device according to claim 8 or 9, characterized in that: The luminescent material in the luminescent layer is tetra-Pt-dbf or tetra-Pt-dbt, wherein tetra-Pt-dbf and tetra-Pt-dbt are represented by the following chemical formulas respectively:

11. An application of an efficient phosphorescent Pt(II) emitter coordinated by a tetradentate [O^N^C^N] ligand as a luminescent material, and a combination of a first compound and a second compound or a combination of SF-BCZ and SF-TRZ as a host material to prepare a luminescent layer and a luminescent device, characterized in that: in, The emitter is represented by the following chemical formula: In this chemical formula, X is independently a 5- or 6-membered heterocyclic ring, R1 to R3 are independently selected from the group consisting of hydrogen, halogen, hydroxy, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, mercapto, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl groups, R4 is independently selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, sulfonyl, phosphino, and combinations thereof, Each pair of adjacent R groups in R1 to R3 is independently one or two independent groups or atoms or is selected to form a 5-6 membered ring, R1 to R3 represent mono-, di-, tri-, tetra- or unsubstituted; The first chemical formula of the first compound is represented by: Among them, in the first chemical formula, X is O or S, Z is hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, or substituted or unsubstituted phenyl, L 1 and L 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group, R a 、R b and R 1 to R 7 are each independently hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, or substituted or unsubstituted C6 to C20 aryl; The second chemical formula of the second compound is represented by: Among them, in the second chemical formula, Y 1 and Y 2 are each independently a single bond or a substituted or unsubstituted C6 to C20 arylene group, Ar 1 and Ar 2 are each independently a substituted or unsubstituted C6 to C20 aryl group or a substituted or unsubstituted C2 to C30 heterocyclic group, R c and R 8 to R 13 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C30 heterocyclyl group, a cyano group, or a combination thereof, m is 0, 1, or 2; SF-BCZ and SF-TRZ are represented by the following chemical formulas: The light-emitting layer or the light-emitting device can be used for fixed visual display units, mobile visual display units, lighting units, keyboards, clothing, decorations, clothing accessories, wearable devices, medical monitoring equipment, wall paper, tablet computers, laptop computers, advertising panels, panel display units, household appliances, and office appliances.

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