High-power organic light-emitting diode

Abstract

The invention discloses a high-power organic light emitting diode. The organic light-emitting material suitable for a high-power organic light-emitting diode is obtained by testing the triplet exciton lifetime of the organic light-emitting material. The high-power organic light-emitting diode comprises an optical radiation layer, the optical radiation layer comprises an organic light-emitting material, and the triplet exciton lifetime of the organic light-emitting material is smaller than or equal to 1 microsecond. The high-power organic light-emitting diode provided by the invention has an extremely low efficiency roll-off effect, and when the external quantum efficiency is reduced to half of the maximum value, the driving current density of the device is greater than 3 amperes / cm < 2 >; the laser has the characteristics of high radiation exitance (greater than 15 milliwatts / cm < 2 >), continuously adjustable spectrum, simple structure, long service life, capability of solution processing, capability of large-area processing and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic light emitting diodes, and in particular relates to a high-power organic light emitting diode. Background Art

[0002] Over the past few decades, organic light-emitting materials, with their low cost, flexibility, and excellent color quality, have been essential components in today's display technology. Organic light-emitting diodes (OLEDs), based on organic semiconductors, offer outstanding advantages such as abundant material resources, simple preparation processes, low cost, and biocompatibility. Their tunable spectral shape, wide spectral half-width, and low temporal coherence make them ideal light sources for applications such as optical coherence tomography, biometric security identification such as facial, iris, and fingerprint recognition, night vision lighting, and food monitoring.

[0003] However, compared with other new luminescent materials, such as perovskites or quantum dots, their performance still has a big gap. In particular, when used in scenes such as lighting, optical communications, and biological imaging systems, the light output power of the device is still relatively weak. In these optical system applications, higher radiant light power density (for example, exceeding the surface solar spectrum irradiation intensity, 100 mW / cm2) or higher near-infrared light power (greater than 10 mW) and good operating stability are beneficial to detection and imaging quality. However, under high current density injection conditions, there are many annihilation and competitive loss processes of excitons or carriers in OLEDs. The annihilation-induced high-order exciton decay significantly reduces the total exciton concentration in the device, and the device efficiency is seriously reduced. This phenomenon of device efficiency decreasing with increasing current density is called "efficiency roll-off" (Advanced Materials. 2013, 25, 6801-6827.), which greatly limits the light output power obtained by increasing current injection to meet practical applications. Currently, efficient and bright organic light-emitting light sources that meet practical application scenarios still face great technical difficulties. New material systems and technical routes are urgently needed to achieve high-brightness organic light-emitting diodes. Summary of the Invention

[0004] In response to the shortcomings of the prior art, the first object of the present invention is to provide a method for screening organic light-emitting materials suitable for high-power organic light-emitting diodes. The triplet exciton lifetime of this type of organic light-emitting material is relatively short, much lower than the triplet lifetime of common fluorescent molecules (less than 1 millisecond).

[0005] A second objective of the present invention is to provide a high-power organic light-emitting diode, in which the triplet exciton lifetime of the organic light-emitting material in the light-radiating layer is less than 1 microsecond. The prepared device has a maximum radiation emittance of greater than 15 milliwatts per square centimeter under DC drive, and has the advantages of low driving voltage and long operating life. The critical current density (the driving current density of the device when the external quantum efficiency drops to half of the maximum value) is greater than 3 amperes per square centimeter, which greatly alleviates the efficiency roll-off effect of the OLED and preliminarily solves the technical difficulties in preparing high-brightness, high-power organic light sources.

[0006] The third object of the present invention is to provide a light gain device, wherein the light gain layer includes the above-selected organic light-emitting material.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for screening organic light-emitting materials suitable for high-power organic light-emitting diodes comprises the following steps:

[0009] The triplet exciton lifetime of an organic light-emitting material is tested. If the triplet exciton lifetime is 1 microsecond or less, the material is suitable for high-power organic light-emitting diodes. The resulting device exhibits a maximum radiant output greater than 15 milliwatts per square centimeter under DC drive, while also offering advantages such as low drive voltage and long operating life, and can achieve continuous adjustment of the emission wavelength.

[0010] The key parameter for screening these organic light-emitting materials for the production of high-power organic light-emitting diodes lies in scientifically measuring the triplet exciton lifetime (τ) of the organic light-emitting materials. The triplet exciton lifetime of organic light-emitting materials can be measured using transient absorption spectroscopy (TAS). Transient absorption spectroscopy is a time-resolved measurement method widely used in photophysics, photochemistry, and photobiology to study the evolution mechanisms of transient substances, such as the diffusion, dissociation, and decay of charges and excitons. It plays a crucial role in predicting fluorescence, phosphorescence, and non-radiative decay mechanisms. For the construction of relevant test systems, please refer to relevant patents CN116879208B, CN116165141A, CN218823921U, CN218823919U, and CN108534896B. For specific experimental principles and data processing, please refer to: Advanced Energy Materials 2024, 14, 2301890; Journal of Chemical Education 2018, 95, 864-871.

[0011] Preferably, if the triplet exciton lifetime of the organic light-emitting material is less than or equal to 0.5 microseconds, it is suitable for high-power organic light-emitting diodes.

[0012] A high-power organic light-emitting diode (OLED) comprises a light-emitting layer comprising an organic light-emitting material having a triplet exciton lifetime of 1 microsecond or less. The resulting OLED device has a maximum radiant output of 15 milliwatts per square centimeter or greater and a critical current density (the driving current density of the device when the external quantum efficiency drops to half its maximum value) of 3 amperes per square centimeter or greater, thereby improving brightness and mitigating the efficiency roll-off effect of OLEDs.

[0013] Preferably, the triplet exciton lifetime of the organic light-emitting material is less than or equal to 0.5 microseconds.

[0014] Preferably, the organic luminescent material is an organic conjugated molecule of an acceptor-donor-acceptor structure (ADA) or an acceptor-π-donor-π-acceptor structure (A-π-D-π-A); according to the core structure of the molecule, it can be derived into organic conjugated molecules such as A-DA'DA type or A-DD'DA type (hereinafter collectively referred to as ADA type organic conjugated molecules), which can achieve high-power and high-efficiency near-infrared band electroluminescence.

[0015] Further preferably, the organic conjugated molecule of the acceptor-donor-acceptor structure or acceptor-π-donor-π-acceptor structure is a molecule of the following structural formula and its isomers:

[0016]

[0017] Preferably, the light emitting wavelength of the organic light emitting material is in the range of 0.7 to 1.3 microns, and the high-power organic light emitting diode is a high-power near-infrared organic light emitting diode.

[0018] The light radiating layer of the present invention comprises one organic light emitting material or a mixture of a plurality of them in any mixing ratio.

[0019] Preferably, the mass percentage of the organic light-emitting material in the light radiation layer is 1-100%;

[0020] Preferably, the light radiating layer is prepared by solution processing.

[0021] Further preferably, the solution processing comprises one of doctor blade coating, spin coating, dip coating, inkjet printing, roll-to-roll printing, screen printing, and lithographic printing;

[0022] Further preferably, the solvent used in the solution processing includes at least one of pentane, dichloromethane, carbon disulfide, carbon disulfide, 1,1-dichloroethane, chloroform, tetrahydrofuran, hexane, trifluoroacetic acid, 1,1,1-trichloroethane, carbon tetrachloride, benzene, acetonitrile, isopropyl alcohol, 1,2-dichloroethane, ethylene glycol dimethyl ether, nitromethane, trichloroethylene, toluene, chlorobenzene, 1,4-dioxane, pyridine, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, p-xylene, xylene, xylene, o-xylene, N,N-dimethylformamide, cyclohexanone, phenol, 1,2-propylene glycol, dimethyl sulfoxide, and acetamide.

[0023] The substrate has a certain degree of transparency in the 600-1500 nanometer region of the electromagnetic spectrum. The substrate should have a smooth surface, and substrates without surface defects are particularly ideal. The substrate can be rigid or elastic. Generally, the selected substrate should have good thermal stability sufficient to withstand temperatures above 150°C, preferably exceeding 300°C, without mechanical property changes. Substrates used for high-power organic light-emitting diodes should have a high thermal conductivity to promote heat dissipation and cooling. Options include metal foil, semiconductor compound wafers, or glass.

[0024] Preferably, the high-power organic light-emitting diode further comprises a substrate having a transmittance greater than or equal to 60% in the 600-1500 nm region of the electromagnetic spectrum and a thermal conductivity greater than or equal to 5.0 W / mK. Thermal conductivity is a parameter that indicates an object's ability to conduct heat, and those skilled in the art will understand the testing process and principles involved. The resulting organic light-emitting diode device has a maximum radiant output greater than or equal to 100 milliwatts per square centimeter and a critical current density (the device's driving current density at which the external quantum efficiency drops to half its maximum value) greater than or equal to 20 amperes per square centimeter, significantly improving brightness and mitigating the efficiency roll-off effect of OLEDs.

[0025] Further preferably, the substrate is at least one of silicon dioxide (quartz), silicon carbide (including intrinsic silicon carbide and silicon carbide of different crystal forms, such as 4H-SiC, 6H-SiC, 3C-SiC, etc.), aluminum nitride, gallium nitride, aluminum oxide (sapphire), and diamond.

[0026] Preferably, the high-power organic light-emitting diode is a face-up structure or an inverted structure; the face-up structure comprises, from bottom to top, substrate, anode, anode modification layer, hole injection (transport) layer / anode buffer layer, light radiation layer, electron injection (transport) layer / cathode buffer layer, cathode modification layer, and cathode; the inverted structure comprises, from bottom to top, substrate, cathode, cathode modification layer, electron injection (transport) layer / cathode buffer layer, light radiation layer, hole injection (transport) layer / anode buffer layer, anode modification layer, and anode.

[0027] The anode is composed of a layer of at least one of a conductive metal, metal oxide, or conductive polymer. The anode should have good electrical conductivity (low resistivity) and a small absolute difference in the HOMO energy level or valence band energy level between the p-type semiconductor material in the hole injection (transport) layer / anode buffer layer or light radiation layer in contact with it (0.2 to 0.5 electron volts), thereby forming a good ohmic contact and facilitating hole injection.

[0028] Further preferably, the anode is made of at least one of aluminum, copper, gold, silver, magnesium, iron, nickel, manganese, platinum, aluminum-doped zinc oxide (AZO), silver nanowires, indium tin oxide (ITO), fluorine tin oxide (FTO), and poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonic acid) (PEDOT:PSS), with a thickness of 80 to 180 nanometers and a sheet resistance of 10 to 15 ohms / □ (unit of sheet resistance), and is constructed by a vacuum deposition method;

[0029] The cathode is composed of a layer of at least one of a conductive metal, metal oxide, or conductive polymer. The cathode should have good electrical conductivity (low resistivity) and a small absolute difference in the LUMO energy level or valence band energy level of the n-type semiconductor material in the electron injection (transport) layer / cathode buffer layer with which it contacts, to form a good ohmic contact and facilitate electron injection.

[0030] Further preferably, the cathode is made of at least one of aluminum, gold, silver, calcium, barium, magnesium, lithium fluoride / aluminum, magnesium-silver alloy, barium fluoride / aluminum, indium tin oxide (ITO) and fluorine tin oxide (FTO), has a thickness of 80 to 280 nanometers, a sheet resistance of 10 to 15 ohms / □, and is constructed by a vacuum deposition method.

[0031] Further preferably, at least one of the cathode or anode (conductive electrode) has a length and width less than or equal to 500 microns; this is beneficial to improving the critical current density of the device and improving the radiation output of the device.

[0032] More preferably, the hole injection (transport layer) is poly (3,4-ethylenedioxythiophene) - poly (styrene sulfonic acid) (PEDOT:PSS) with a thickness of 5 to 100 nm, and the hole injection (transport layer) is constructed by spin coating.

[0033] Further preferably, the electron injection (transport layer) is at least one of poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (abbreviated as PFN), poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide (abbreviated as PFN-Br) and (N,N-dimethyl-ammonium N-oxide)propylperylene diimide and its derivatives PDIN, PDINN, PDINO, PNDIT-F3N, PNDIT-F3N-Br, and its thickness is 5 to 100 nanometers. The electron injection (transport layer) is constructed by spin coating.

[0034] A light gain device comprises a light gain layer, wherein the light gain layer comprises the above-mentioned organic light-emitting material.

[0035] Preferably, the light gain layer comprises a mixture of one or more organic light-emitting materials in any mixing ratio, and can achieve continuously adjustable emission spectrum.

[0036] Preferably, the mass percentage of the organic light-emitting material in the light gain layer is 1-100%.

[0037] Preferably, the spontaneous radiation amplification peak of the optical gain device is in the near-infrared band.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) The preparation method of the present invention is simple, the material cost is low, and it is feasible.

[0040] (2) The organic light-emitting diode provided by the present invention has high radiation emittance (greater than 15 mW / cm2) and high brightness; it also has an extremely low efficiency roll-off effect. When the external quantum efficiency drops to half of the maximum value, the driving current density of the device is greater than 3 amperes / cm2, which is suitable for high power.

[0041] (3) Compared with the traditional organic light-emitting diodes with a turn-on voltage of 5 to 10 volts (Nature Photonics, 2020, 14, 570-577; Advanced Materials 2009, 21111-21116), the light-emitting diodes prepared by the present invention have a lower turn-on voltage (0.8-3 volts). At the same driving current density, they have a lower driving voltage, resulting in lower power consumption and more energy-saving and environmentally friendly.

[0042] (4) The organic light emitting diode provided by the present invention also has the characteristics of long service life, simple structure, solution processing, and low-cost large-area processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the structure of the upright organic light-emitting device provided by the present invention, wherein: 1 - substrate; 2 - anode; 3 - anode modification layer; 4 - hole injection (transport) layer / anode buffer layer; 5 - light radiation layer; 6 - electron injection (transport) layer / cathode buffer layer; 7 - cathode modification layer; 8 - cathode.

[0044] Figure 2 The electroluminescence spectra of the near-infrared light-emitting diode devices of the ADA-type compounds in Examples 1, 2, 3, and 4 are shown.

[0045] Figure 3 The current density-voltage characteristic curves of the near-infrared light-emitting diode devices of the ADA-type compounds in Examples 1, 2, 3, and 4 are shown.

[0046] Figure 4 The current density-radiant brightness characteristic curves of the near-infrared light-emitting diode devices of the ADA-type compounds in Examples 1, 2, 3, and 4 are shown.

[0047] Figure 5 The external quantum efficiency-current density characteristic curves of the near-infrared light-emitting diode devices of the ADA-type compounds in Examples 1, 2, 3, and 4 are shown.

[0048] Figure 6 In Examples 5-8, a blend of F8TBT as the host and compound 3 as the guest (the mass fraction of compound 3 is 50%, 70%, 80% and 100%, respectively) is used as the light radiation layer to achieve the electroluminescent emission spectrum of the organic OLED device with continuously adjustable emission wavelength.

[0049] Figure 7 This is the triplet exciton decay curve of compound 2 in test example 1. According to exponential fitting, the triplet exciton lifetime of compound 2 is 0.17 microseconds.

[0050] Figure 8 In Test Example 2, a blend of CBP as the host and Compound 2 as the guest (the mass fraction of Compound 2 is 5%) is used as the optical gain layer. The relationship curve of the emission spectrum intensity, spectral half-maximum width and pump light intensity is obtained, and the spontaneous radiation amplification pump threshold as the optical gain layer is fitted.

[0051] Figure 9 In Test Example 2, a blend of CBP as the host and compound 2 as the guest (the mass fraction of compound 2 is 2%, 5%, and 10%, respectively) is used as the light gain layer to achieve the emission spectrum of an organic laser device with a continuously adjustable emission wavelength by a spontaneous radiation amplification effect. DETAILED DESCRIPTION

[0052] The structures of the organic light emitting diode or organic electroluminescent device, photoluminescent film or components in the present invention are described below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] Example 1

[0054] Several 15 mm × 15 mm indium tin oxide (ITO) conductive sapphire substrates from the same batch were prepared. The ITO thickness was approximately 130 nm, and the sheet resistance was approximately 15 ohms / square. The substrates were ultrasonically cleaned in acetone, semiconductor cleaning agent, deionized water, and isopropyl alcohol, dried with nitrogen, and placed in a constant-temperature oven for later use. Prior to use, the ITO sapphire substrates were plasma bombarded in a plasma etcher for 10 minutes. The substrates were then placed on a spin coater and an appropriate amount of a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) suspension (Xi'an Biolight Optoelectronics Technology Co., Ltd., Model AI4083) was dripped onto the surface. The suspension was filtered through a 0.45 μm polyvinylidene fluoride (PVDF) membrane before addition. The spin coater was then spin-coated at 3000 rpm for 30 seconds to form a 30-nm-thick hole injection (transport) layer / anode buffer layer. After film formation, the ITO conductive glass substrate coated with PEDOT:PSS was placed on a heating platform at 150°C to remove the residual solvent to obtain a stable film.

[0055] The film was then transferred to a nitrogen-filled glove box and placed on a suitable spin coater. A 20 mg / mL solution of Compound 1 (a mixture of toluene and chloroform, with a volume ratio of 1:1) was dropwise added to the surface of the hole injection (transport) layer / anode buffer layer. The spin coater was then turned on and operated at a speed of 900 to 3000 rpm. The resulting light radiating layer had a thickness of 60 to 200 nm, preferably 80 to 100 nm. In this embodiment, the spin coating speed was 1800 rpm, and the thickness of the light radiating layer was 90 nm. After the film is formed stably, the pre-configured electron injection (transport) layer / cathode buffer layer poly (9,9-bis (3'- (N,N-dimethyl) -N-ethylaminopropyl-2,7-fluorene) -alt-2,7- (9,9-dioctylfluorene)) dibromide (abbreviated as PFN-Br, the solvent is methanol, the concentration is 0.6 mg / ml) is spin-coated to prepare a PFN-Br film. The thickness of the PFN-Br film in this embodiment is 10 nm. Then, the film is moved into a vacuum evaporation chamber and the vacuum reaches 3 × 10 -4After the Pa, a 3-nanometer barium film is deposited via thermal evaporation as the cathode modification layer, followed by a 100-nanometer silver film as the electrode. Using a pre-customized mask, each electrode and active layer can be patterned into a specific pattern. In this example, the pattern is square, and the light-emitting area is 200 x 200 square microns.

[0056] Example 2

[0057] The process for preparing an organic light-emitting diode device is the same as that in Example 1, except that Compound 2 is used as the luminescent material of the light-emitting layer. The light-emitting layer solvent used in this example is toluene with a concentration of 22 mg / ml. The spin coating speed is 1400 rpm, and the thickness of the light-emitting layer film is 120 nm.

[0058] Example 3

[0059] The fabrication process for the organic light-emitting diode device was identical to that of Example 1, except that Compound 3 was used as the luminophore for the light-emitting layer. The solvent used for the light-emitting layer in this example was chloroform at a concentration of 18 mg / ml. The spin coating speed was 1800 rpm, and the thickness of the light-emitting layer film was 110 nm. The electron injection (transport) layer / cathode buffer layer used in this example was a solution of (N,N-dimethyl-ammonium N-oxide)propylperylene diimide (PDINO) in methanol at a concentration of 1.5 mg / ml, and the film thickness was 10 nm.

[0060] Example 4

[0061] The process for fabricating an organic light-emitting diode device was the same as that in Example 1, except that Compound 4 was used as the luminophore of the light-emitting layer. The light-emitting layer solvent used in this example was chlorobenzene at a concentration of 22 mg / ml, the spin coating speed was 1300 rpm, and the light-emitting layer film thickness was 130 nm. The electron injection (transport) layer / cathode buffer layer used in this example was a mixed solution of (N,N-dimethyl-ammonium N-oxide)propylperylene diimide (PDINO) and poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide (PFN-Br) (mass fraction ratio 1:1) in methanol at a concentration of 1.5 mg / ml, and the film thickness was 10 nm.

[0062] Table 1

[0063]

[0064]

[0065] Table 1 lists the current-voltage curves and emission spectrum parameters of the devices manufactured according to Examples 1 to 4, which fully demonstrates the applicability of ADA-type compounds as light-radiating layers in OLEDs. The spectral range is in the near-infrared band, and they have the characteristics of high brightness, low turn-on voltage, tolerance to high current density, high efficacy, low efficiency roll-off, continuous spectrum adjustment, simple structure, long life, solution processing, and continuous large-area processing.

[0066] Examples 5-8

[0067] An OLED device was fabricated in the same manner as in Example 3, except that glass was used as the transparent substrate; a blend of poly[(9,9-dioctylfluorene)-2,7-diglycol(4,7-bis(3-hexylthiophen-5-yl)-2,1,3-benzothiadiazole)-2',2"-diyl] (hereinafter referred to as F8TBT) as the host and Compound 3 as the guest (the mass ratios of Compound 3 were 50%, 70%, 80%, and 100%, respectively) was used as the light radiation layer. In this example, the solvent was chloroform at a concentration of 12 mg / ml, the spin coating speed was 1800 rpm, and the thickness of the light radiation layer was 100 nm.

[0068] Table 2

[0069]

[0070] The advantages of using this hybrid solution are: by using an appropriate compound as the main body (here F8TBT) to dilute the ADA-type compound, the occurrence of aggregation quenching effect can be effectively suppressed, thereby improving the quantum efficiency and irradiance of the device; it can also achieve continuous adjustment of the radiation spectrum within a certain wavelength range, unlike inorganic materials that use molecular beam epitaxial growth or lithography to adjust the emission wavelength of the device through gratings or quantum wells; this solution is easy to manufacture and extremely low cost.

[0071] Comparative Example 1

[0072] An OLED device was fabricated in the same manner as in Example 8, using glass as the transparent substrate; the difference being that poly[2-methoxy-5-(2-ethylhexyloxy-1,4-phenylene vinylene]] (hereinafter referred to as MEH-PPV) was used as the light radiating layer. Over the past few decades, organic fluorescent molecules based on polythiophene and ladder-shaped poly(p-phenyl) have been widely used in organic light-emitting diodes, and their excited state properties have been extensively studied. According to relevant research reports, their triplet exciton lifetimes have been determined to be 20 to 200 microseconds, with MEH-PPV having a triplet exciton lifetime of 92 microseconds (Triplet state dynamics on isolated conjugated polymer chains. Chem. Phys. 285, 3-11, (2002)). In this example, the solvent was toluene at a concentration of 10 mg / ml, the spin coating speed was 1500 rpm, and the light radiating layer film thickness was 80 nm.

[0073] Table 3

[0074]

[0075] Table 3 lists the OLED devices prepared according to Comparative Example 1 using the luminescent material MEH-PPV with a triplet exciton lifetime of 92 microseconds as the light radiation layer. When the external quantum efficiency drops to half of the maximum value, the corresponding critical current density is less than 1 ampere / square centimeter, and the maximum radiation brightness is also relatively low.

[0076] Test Example 1

[0077] Several quartz substrates from the same batch, measuring 15×15 mm, were ultrasonically cleaned using acetone, semiconductor cleaning agent, deionized water, and isopropyl alcohol, followed by nitrogen drying and placement in a constant-temperature oven. Prior to use, the quartz substrates were plasma-bombarded in a plasma etcher for 10 minutes. The substrates were then placed in a nitrogen-filled glove box and placed on a suitable spin coater. A 20 mg / ml toluene solution of Compound 2 was dropwise applied to the substrate surface. The spin coater was then turned on and operated at a speed of 900–2000 rpm. The resulting light-emitting layer film, spin-coated in this manner, had a thickness of 60–150 nm, preferably 90–130 nm. In this embodiment, the spin coating speed was 1200 rpm, resulting in a light-emitting layer film thickness of 120 nm.

[0078] The transient absorption spectroscopy test uses a titanium sapphire femtosecond laser (Astrella, Coherent Inc) to generate femtosecond pulse light with a central wavelength of 800 nanometers, a repetition rate of 1000 Hz, and a laser pulse width of 100 femtoseconds. It then enters an optical parametric amplifier (OPerASolo, Coherent Inc) to generate pump light of the wavelength required for the experiment (670 nanometers, 540 nanometers), and the probe light (supercontinuum white light, wavelength range 350-950 nanometers) is generated by a nanosecond laser triggered by an electrical pulse. The pump light and probe light enter the transient absorption spectrometer (Helios-Eos Fire, Ultrafast system) and are focused on the sample. Time-resolved detection is achieved by electrically triggering the delayed probe light. The probe light absorbed by the sample carries information about the excited state and ground state of the particle and is finally incident on the optical fiber probe. During the measurement, a time delay line is used to change the time when the probe light is delayed relative to the pump light to reach the sample, so that the spectral information of the sample particles at different time delays after being excited can be obtained, such as Figure 7 As shown. The decay process of the excited state excitons of compound 2 is characterized by the superposition of singlet excitons with a shorter lifetime and triplet excitons with a relatively longer lifetime. Combined with the exponential decay model fitting, the triplet exciton lifetime of compound 2 is 0.16 microseconds. According to Example 2, the emission peak of the organic near-infrared light-emitting diode using compound 2 as the light radiation layer is located at 0.74 microns. In the DC drive mode, the maximum radiation brightness is greater than 1600 watts / steradian / square meter, and the maximum radiation emittance is greater than 500 milliwatts / square centimeter. It is precisely because of the shorter triplet exciton lifetime that these compounds have achieved more excellent technical effects.

[0079] Test Example 2

[0080] Several quartz substrates from the same batch, measuring 15×15 mm, were ultrasonically cleaned using acetone, semiconductor cleaning agent, deionized water, and isopropyl alcohol, dried with nitrogen, and placed in a constant-temperature oven for later use. The light-gain layer solution consisted of a mixture of Compound 2 and 4,4-bis(9-carbazole)biphenyl (CBP), with the mass fractions of Compound 2 at 2%, 5%, and 10%, respectively. The solvent was chloroform at a concentration of 15 mg / ml. Before use, the quartz substrates were plasma-bombarded in a plasma etcher for 10 minutes. The substrates were then placed in a nitrogen-filled glove box and placed on a suitable spin coater. The prepared light-gain layer solution was dripped onto the surface of the quartz substrates. The spin coater was then turned on and operated at a speed of 900–2000 rpm. The resulting light-radiating layer film, spin-coated in this manner, had a thickness of 60–150 nm, preferably 90–130 nm. In this embodiment, the spin coating speed was 1200 rpm, resulting in a light-radiating layer film with a thickness of 120 nm.

[0081] The spontaneous emission amplification effect of the optical gain material in organic laser devices was tested using an Nd:YAG laser (QuantelLaser, Q-smart, QSM-100-20-G) to excite the optical gain film at a repetition rate of 20 Hz, a pulse width of 5 nanoseconds, and an excitation wavelength of 532 nanometers. After passing through an aperture and a neutral attenuator plate, the laser was focused by a cylindrical lens to produce a uniform, small spot (0.5 mm × 4 mm). The mass fraction of compound 2 in the optical gain film was 2%, 5%, and 10%, respectively. The emission spectra and the excitation light intensity were collected and recorded perpendicular to the excitation light using a spectrometer (QEPro, Ocean Optics).

[0082] like Figure 8 The figure shows the trend of the emission intensity (solid circles, left axis) and the full width at half maximum (FWHM) of the emission spectrum (open squares, right axis) of an optical gain film containing 5% compound 2, as compared to the excitation light intensity. References (such as CN113437641A) often use this trend to determine the threshold energy for spontaneous emission amplification, judging the potential of the molecule as a laser gain layer. In this test example, the threshold energy was 13.6 μJ / cm², demonstrating its potential as an optical gain layer in organic laser devices. Figure 9 The emission spectra of optical gain films with mass fractions of compound 2 of 2%, 5% and 10% were recorded, and the spontaneous radiation amplification peaks were 710 nm, 715 nm and 726 nm, respectively, achieving continuous adjustment of the emission wavelength.

[0083] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for screening organic light-emitting materials suitable for high-power organic light-emitting diodes, characterized in that: The following steps are involved: The triplet exciton lifetime of the organic light-emitting material is tested. If the triplet exciton lifetime of the organic light-emitting material is less than or equal to 1 microsecond, it is suitable for high-power organic light-emitting diodes.

2. A high-power organic light-emitting diode, characterized in that: The method comprises a light radiation layer, wherein the light radiation layer comprises an organic light emitting material, and the triplet exciton lifetime of the organic light emitting material is less than or equal to 1 microsecond.

3. The high-power organic light-emitting diode according to claim 2, characterized in that: The organic light-emitting material is an organic conjugated molecule of an acceptor-donor-acceptor structure or an acceptor-π-donor-π-acceptor structure; The organic conjugated molecules of the acceptor-donor-acceptor structure or acceptor-π-donor-π-acceptor structure are molecules of the following structural formula and their isomers:

4. The high-power organic light-emitting diode according to claim 2, characterized in that: The mass percentage of the organic light-emitting material in the light radiation layer is 1-100%; The light radiating layer is prepared by solution processing.

5. The high-power organic light-emitting diode according to claim 4, characterized in that: The solution processing includes one of blade coating, spin coating, dip coating, inkjet printing, roll-to-roll printing, screen printing, and lithographic printing; The solvent used in the solution processing includes at least one of pentane, dichloromethane, carbon disulfide, carbon disulfide, 1,1-dichloroethane, chloroform, tetrahydrofuran, hexane, trifluoroacetic acid, 1,1,1-trichloroethane, carbon tetrachloride, benzene, acetonitrile, isopropyl alcohol, 1,2-dichloroethane, ethylene glycol dimethyl ether, nitromethane, trichloroethylene, toluene, chlorobenzene, 1,4-dioxane, pyridine, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, p-xylene, xylene, xylene, o-xylene, N,N-dimethylformamide, cyclohexanone, phenol, 1,2-propylene glycol, dimethyl sulfoxide, and acetamide.

6. The high-power organic light-emitting diode according to claim 2, characterized in that: The high-power organic light-emitting diode further comprises a substrate, wherein the substrate has a transmittance greater than or equal to 60% in the 600-1500 nanometer region of the electromagnetic spectrum and a thermal conductivity greater than or equal to 5.0 W / mK.

7. The high-power organic light-emitting diode according to claim 6, characterized in that: The substrate is at least one of silicon dioxide, silicon carbide, aluminum nitride, gallium nitride, aluminum oxide, and diamond.

8. The high-power organic light-emitting diode according to claim 2, characterized in that: The high-power organic light-emitting diode has a face-up structure or an inverted structure; the face-up structure comprises, from bottom to top, a substrate, an anode, an anode modification layer, a hole injection (transport) layer / an anode buffer layer, a light radiation layer, an electron injection (transport) layer / anode buffer layer, a cathode modification layer, and a cathode; the inverted structure comprises, from bottom to top, a substrate, a cathode, a cathode modification layer, an electron injection (transport) layer / anode buffer layer, a light radiation layer, a hole injection (transport) layer / anode buffer layer, an anode modification layer, and an anode.

9. The high-power organic light-emitting diode according to claim 8, characterized in that: The anode is made of at least one of aluminum, copper, gold, silver, magnesium, iron, nickel, manganese, platinum, aluminum-doped zinc oxide, silver nanowires, indium tin oxide, fluorine tin oxide, and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), has a thickness of 80 to 180 nanometers, a sheet resistance of 10 to 15 ohms / square, and is constructed by a vacuum deposition method; The cathode is made of at least one of aluminum, gold, silver, calcium, barium, magnesium, lithium fluoride / aluminum, magnesium-silver alloy, barium fluoride / aluminum, indium tin oxide, and fluorine tin oxide, has a thickness of 80 to 280 nanometers, a sheet resistance of 10 to 15 ohms / square, and is constructed by a vacuum deposition method; The length and width of at least one of the cathode or anode is less than or equal to 500 microns; The electron injection (transport layer) is at least one of poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)], poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide and (N,N-dimethyl-ammonium N-oxide)propylperylene diimide and its derivatives PDIN, PDINN, PDINO, PNDIT-F3N, PNDIT-F3N-Br.

10. An optical gain device, characterized in that: The light gain layer comprises the organic light emitting material according to claim 2 or 3.

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