Low-voltage organic light-emitting diode device
By optimizing the LUMO energy level difference between donor materials and acceptor materials in organic electroluminescent diode devices, and combining specific material combinations and spacer design, the problem of high OLEDs light-on voltage is solved, achieving low voltage and high voltage Efficient luminous performance significantly reduces power consumption and improves stability.
Patent Information
- Application Number
- CN202411360403.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-01-07
AI Technical Summary
The light-on voltage of existing organic light-emitting diodes (OLEDs) is high, resulting in high power consumption and poor stability, and the light-on voltage of different light colors varies greatly, affecting practical applications.
Organic electroluminescent diode devices using a laminated structure, including a donor material layer and an acceptor material layer, have a LUMO energy difference of ≥0.4 eV, and are designed by preferred material combinations and structural designs, such as rubrene and fullerene , hole-type materials, etc., optimize the energy level difference and material selection of devices, and add spacers to suppress energy back-pass loss.
Achieve low light-on voltage and working voltage, excellent current efficiency and luminous performance. The light-on voltage of the red light device is as low as 1.1V, and the light-on voltage of the blue light device is 1.8V, which is significantly lower than the existing technology, and the current efficiency is improved. 40%.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of light emitting devices, and in particular relates to a low voltage organic electroluminescent diode device. Background Art
[0002] Organic light-emitting diodes (OLEDs) are considered to be a new generation of display and lighting technology due to their advantages such as self-luminescence, fast response speed, rich colors, soft light, no blue light damage, thinness, and large-area flexibility. In organic semiconductors, excitons are generated by the recombination of electrons in the LUMO orbit and holes in the HOMO orbit. The energy of the excitons depends on the energy level difference between the LUMO orbit and the HOMO orbit of the luminescent material. For OLEDs, they must be driven by electrical energy higher than the energy level difference to be successfully turned on, which often results in a higher turn-on voltage of the device, resulting in higher power consumption and poor stability. Moreover, the band gap of organic materials of different light colors is quite different, which also causes different turn-on voltages of OLEDs of different light colors. The large difference in turn-on voltages brings great problems to practical applications. Summary of the invention
[0003] In order to overcome the above problems in the prior art, one of the objectives of the present invention is to provide an organic light emitting diode device.
[0004] A second object of the present invention is to provide application of the above organic light emitting diode device in light emitting electronic products.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is:
[0006] The first aspect of the present invention provides an organic electroluminescent diode device, comprising a stacked anode, a hole injection layer, a donor material layer, an acceptor material layer, an electron injection layer and a cathode; the donor material layer contains a donor material; the acceptor material layer contains an acceptor material; the difference between the absolute value of the LUMO energy level of the donor material and the LUMO energy level of the acceptor material is ≥0.4eV. .
[0007] Preferably, the singlet energy level S1-(triplet energy level T1×2 of the donor material) of the donor material is ≤ 0.2 eV.
[0008] Preferably, the donor material is selected from rubrene materials, and the acceptor material is selected from fullerene materials; further preferably, the donor material is selected from rubrene, and the acceptor material is selected from at least one of C60 and C70.
[0009] Preferably, the thickness of the donor material layer is 5-50 nm.
[0010] Preferably, the thickness of the receptor material layer is 5-50 nm.
[0011] Preferably, the singlet energy level S1-(triplet energy level T1×2) of the acceptor material is ≤ 0.2 eV. Preferably, the acceptor material is selected from at least one of pyrene compounds, phenanthrene compounds and anthracene compounds; the donor material is selected from hole-type materials; and the hole mobility of the hole-type material is greater than the electron mobility.
[0012] Preferably, the hole-type material is selected from at least one of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), 4,4',4"-tri(carbazole-9-yl)triphenylamine (TCTA), and 4,4',4"-tri(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA).
[0013] Preferably, the anthracene compound includes at least one of 2-methyl-9,10-di(2-naphthyl)anthracene (MADN), dinaphthylanthracene (ADN), and 2-(4-(10-(3-(9H-carbazole-9-yl)phenyl)anthracene-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (PAC).
[0014] Preferably, the material of the anode is selected from at least one of ITO, IZO, and AZO (aluminum-doped zinc oxide).
[0015] Preferably, the cathode material is selected from at least one of Ag, magnesium-silver alloy and Al.
[0016] Preferably, the thickness of the electron transport layer is 10 to 50 nm.
[0017] Preferably, the hole injection layer has a thickness of 10 to 50 nm.
[0018] Preferably, the cathode layer has a thickness of 100-200 nm.
[0019] Preferably, the thickness of the anode layer is 100-200 nm.
[0020] Preferably, the organic light-emitting diode device further comprises a spacer layer, which is located between the donor material layer and the acceptor material layer. The function of the spacer layer is to suppress the energy return loss during the light-emitting process.
[0021] Preferably, the spacer layer contains a barrier material; the singlet energy level S1 of the barrier material is higher than the singlet energy level S1 of the donor material; the triplet energy level T1 of the barrier material is not lower than the triplet energy level T1 of the donor material; the triplet energy level T1 of the barrier material is not higher than the triplet energy level T1 of the acceptor material.
[0022] Preferably, the barrier material is a bipolar material, and the hole mobility and electron mobility thereof differ within an order of magnitude.
[0023] Preferably, the barrier material is selected from 4,4-bis(9-carbazole)biphenyl.
[0024] Preferably, the thickness of the spacer layer is 1-10 nm.
[0025] Preferably, the organic electroluminescent diode device further comprises a hole transport material layer and / or an electron transport material layer; the hole transport material layer is located between the hole injection layer and the donor material layer; the electron transport material layer is located between the acceptor material layer and the electron injection layer.
[0026] Preferably, the method for preparing the organic electroluminescent diode device comprises the following steps: sequentially evaporating a hole injection layer, a donor material layer, an acceptor material layer, an electron injection layer and a cathode on the anode to obtain the device.
[0027] The second aspect of the present invention provides use of the organic light emitting diode device described in the first aspect of the present invention in a light emitting electronic product.
[0028] The beneficial effects of the present invention are as follows: the organic electroluminescent diode device in the present invention has a lower turn-on voltage and operating voltage, as well as excellent current efficiency and luminescence performance. Specifically, when the device is a red light device, its turn-on voltage is as low as 1.1V, and the operating voltage is 1.5V; when the device is a blue light device, its turn-on voltage is 1.8V, and the operating voltage is 2.4V, which are significantly lower than the organic electroluminescent diodes in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 This is an energy level diagram of each material used in Examples 1 to 3.
[0030] Figure 2 This is a light emission spectrum diagram of the low voltage organic light emitting diode device of Example 1.
[0031] Figure 3 This is a light emission spectrum diagram of the low voltage organic light emitting diode device of Example 2.
[0032] Figure 4This is a light emission spectrum diagram of the low voltage organic light emitting diode device of Example 3.
[0033] Figure 5 It is an IVL curve diagram of the low voltage organic light emitting diode device of Example 1.
[0034] Figure 6 It is an IVL curve diagram of the low voltage organic light emitting diode device of Example 2.
[0035] Figure 7 It is an IVL curve diagram of the low voltage organic light emitting diode device of Example 3. DETAILED DESCRIPTION
[0036] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.
[0037] The raw material information used in the embodiments of the present invention is as follows:
[0038] ITO: Indium Tin Oxide;
[0039] HAT-CN: 1,4,5,8,9,11-hexaazatriphenylhexanitrile;
[0040] Rubrene: 5,6,11,12-tetraphenyltetracene, with a singlet energy level S1 of 2.23 eV and a triplet energy level T1 of 1.14 eV.
[0041] C70: Fullerene;
[0042] TmPyPB: 3,3'-(5'-(3-(3-pyridyl)phenyl)-[1,1':3',1"-terphenyl]-3,3"-diyl)bipyridine, CAS No.: 921205-03-0;
[0043] m-MTDATA: 4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine;
[0044] AND: 9,10-di(2-naphthyl)anthracene, whose singlet energy level S1 is 3.2 eV and triplet energy level T1 is 1.7 eV;
[0045] CBP: 4,4-di(9-carbazole)biphenyl; its singlet energy level S1 is 3.4eV, and triplet energy level T1 is 2.6eV. Its electron mobility is about 2*10 -5 cm 2 ·V–1 ·s –1 , the hole mobility is 6*10 -5 cm 2 ·V –1 ·s –1 .
[0046] Example 1
[0047] This example provides a low-voltage organic electroluminescent diode device, including a transparent anode layer, a hole injection layer, a donor material layer, an acceptor material layer, an electron transport layer, an electron injection layer and a cathode layer stacked in sequence; wherein the material of the transparent anode layer is ITO, and the thickness of the transparent anode layer is 170nm; the material of the hole injection layer is HAT-CN, and the thickness of the hole injection layer is 50nm; the material of the donor material layer is Rubrene, and the thickness of the donor material layer is 20nm; the material of the acceptor material layer is C 70 The thickness of the acceptor material layer is 20nm; the material of the electron transport layer is TmPyPB, the thickness of the electron transport layer is 25nm; the material of the electron injection layer is LiF, the thickness of the electron injection layer is 1nm; the material of the cathode layer is Al metal, the thickness of the cathode layer is 150nm. The energy level diagram of each material used in this example is shown in Figure 1 (a) shows that the device in this example is denoted as device 1: ITO / HAT-CN (50nm) / Rubrene (20nm) / C 70 (20nm) / TmPyPB(25nm) / LiF(1nm) / Al(150nm).
[0048] Example 2
[0049] This example provides a low-voltage organic electroluminescent diode device, including a transparent anode layer, a hole injection layer, a donor material layer, an acceptor material layer, an electron transport layer, an electron injection layer and a cathode layer stacked in sequence; wherein the material of the transparent anode layer is ITO, and the thickness of the transparent anode layer is 170nm; the material of the hole injection layer is HAT-CN, and the thickness of the hole injection layer is 50nm; the material of the donor material layer is m-MTDATA, and the thickness of the donor material layer is 25nm; the material of the acceptor material layer is AND, and the thickness of the acceptor material layer is 25nm; the material of the electron transport layer is TmPyPB, and the thickness of the electron transport layer is 25nm; the material of the electron injection layer is LiF, and the thickness of the electron injection layer is 1nm; the material of the cathode layer is Al metal, and the thickness of the cathode layer is 150nm. The energy level diagram of each material used in this example is shown as follows: Figure 1As shown in (b), the device in this example is recorded as device 2: ITO / HAT-CN (50nm) / m-MTDATA (25nm) / AND (25nm) / TmPyPB (25nm) / LiF (1nm) / Al (150nm).
[0050] Example 3
[0051] This example provides a low-voltage organic electroluminescent diode device, including a transparent anode layer, a hole injection layer, a donor material layer, a spacer layer, an acceptor material layer, an electron transport layer, an electron injection layer and a cathode layer stacked in sequence; wherein the material of the transparent anode layer is ITO, and the thickness of the transparent anode layer is 170nm; the material of the hole injection layer is HAT-CN, and the thickness of the hole injection layer is 50nm; the material of the donor material layer is m-MTDATA, and the thickness of the donor material layer is 25nm; the material of the spacer layer is CBP, and the thickness of the spacer layer is 5nm; the material of the acceptor material layer is AND, and the thickness of the acceptor material layer is 25nm; the material of the electron transport layer is TmPyPB, and the thickness of the electron transport layer is 25nm; the material of the electron injection layer is LiF, and the thickness of the electron injection layer is 1nm; the material of the cathode layer is Al metal, and the thickness of the cathode layer is 150nm. The energy level diagram of each material used in this example is shown as follows: Figure 1 (b) shows that the device in this example is denoted as device 3: ITO / HAT-CN (50nm) /
[0052] m-MTDATA(25nm) / CBP(5nm) / AND(25nm) / TmPyPB(25nm) / LiF(1nm) / Al(150nm).
[0053] The low voltage organic light emitting diode devices in Examples 1 to 3 can be prepared by a preparation method comprising the following steps, specifically:
[0054] First, the ITO glass substrate was cleaned twice in a cleaning machine with glass cleaning liquid and pure water, and then dried in an 80°C oven for 30 minutes. After drying, the ITO glass substrate was placed in a vacuum thermal evaporation machine for evaporation. During the evaporation process, the system was kept at 10 -7 The vacuum degree is about 1000 Torr, and the rate and thickness of the deposited film are monitored by a quartz crystal. The evaporation rate of organic materials is The evaporation rate of LiF is The evaporation rate of Al cathode is When one material is evaporated to a specified thickness, the evaporation is stopped, and then the evaporation of the next layer of material is started. When all materials are evaporated, they are packaged with a glass packaging plate and epoxy resin in a nitrogen environment, and cut in an atmosphere at room temperature to obtain low-voltage organic electroluminescent diode devices in Examples 1 to 3.
[0055] Device performance test:
[0056] The low voltage organic light emitting diode devices in Examples 1 to 3 are connected to a power source to emit light. The light emission spectra are shown in FIG. Figure 2 to Figure 4 As shown by Figure 2 to Figure 4 It can be seen that the device in Example 1 is a red light device, and the devices in Examples 2 and 3 are all blue light devices. After adding the spacer layer in Example 3, the device luminescence spectrum does not change, and the central wavelength of the blue light luminescence spectrum is 464nm. Then test the device performance, the specific test method is: first, under a constant current I1, use a spectroradiometer to test the brightness L1 and spectrum of the OLED device, then transfer the device to the test black box of the IVL system, use the constant current mode interface, select the corresponding RGB channel, set the same current value I1 as the previous spectroradiometer to test the brightness of the OLED device, measure the silicon photodiode sensing brightness L2 of the device in the test black box, and obtain the corresponding test brightness ratio (also called correction factor) γ=L1 / L2, then switch the constant current mode interface to the test interface, set the test voltage range and the number of test points, start the test, and the software automatically obtains the IVL curve. The brightness corresponds to the brightness value sensed by the silicon photodiode. Multiply this brightness by the correction factor γ to obtain the actual brightness L of the OLED device, and finally draw the device IVL curve, as shown in the following figure. Figure 5 to Figure 7 As shown in Figure 2, the device current efficiency (LE) refers to the ratio of the device's outward luminance to the device's current density, with the unit being candela per ampere (cd A -1 ); can be expressed by the following formula:
[0057]
[0058] Where B is the luminous brightness, unit is cd m -2 ; S is the effective light-emitting area of the device, unit: cm 2 ; J is the current density of the device when it is working, in mA cm -2 .
[0059] The performance of the low voltage organic light emitting diode devices in Examples 1 to 3 measured according to the above test method is shown in Table 1 below, where the turn-on voltage (denoted as V on ) is the brightness of the device reaches 1cd / m 2 Working voltage at 100cd / m 2 Indicates brightness at 100cd / m 2 The device performance is shown below, where V represents the corresponding device voltage, J represents the corresponding current density, and LE represents the corresponding current efficiency of the device.
[0060] Table 1 Device performance test results of Examples 1 to 3
[0061]
[0062]
[0063] From Table 1 and Figure 5 It can be seen that the turn-on voltage of the device 1 in Example 1 of the present invention is only 1.1V. Compared with the OLEDs red light device in the prior art (whose turn-on voltage is about 1.8V), the turn-on voltage of the device in Example 1 is significantly reduced. At the same time, the device 1 has a turn-on voltage of only 1.1V at 100cd / m 2 Under full brightness, the voltage is only 1.5V and the current efficiency reaches 2.1cd / A. The extremely low device start-up voltage is conducive to reducing device power consumption, which plays an important role in OLEDs lighting applications.
[0064] From Table 1 and Figure 6 It can be seen that the turn-on voltage of the device 2 in Example 2 of the present invention is only 1.8V. Compared with the OLED blue light device in the prior art (whose turn-on voltage is about 2.2V), the turn-on voltage of the device in Example 2 is significantly reduced. At the same time, the device 2 has a turn-on voltage of only 1.8V at 100cd / m 2 At low brightness, the voltage is only 2.4V, and the current efficiency reaches 5.3cd / A. This lower device start-up voltage is conducive to reducing device power consumption and is conducive to the design of portable OLEDs display application devices (the rated voltage of the lithium-ion battery loaded in most mobile devices is 3.7V).
[0065] From Table 1 and Figure 7 It can be seen that in order to suppress the energy return process, device 3 in Example 3 introduces a spacer layer on the basis of Example 2 to prepare high-efficiency low-voltage device OLEDs. A thin layer of CBP is added between m-MTDATA and ADN as a spacer layer. The triplet energy level of CBP is similar to that of m-MTDATA. The triplet excitons can be transferred to ADN, but the singlet energy level of CBP is higher than that of ADN, which can effectively prevent the singlet energy from being returned. After the introduction of the spacer layer, the maximum external quantum efficiency of device 3 increased from 2.1% to 3.07%. The turn-on voltage of device 3 in Example 3 is 1.8V, which is consistent with the turn-on voltage of device 2 in Example 2. Compared with the OLED blue light device in the prior art (whose turn-on voltage is about 2.2V), the turn-on voltage of the device is greatly reduced. At the same time, device 3 has a turn-on voltage of 100cd / m 2 Under brightness, the voltage is also 2.4V, and the current efficiency reaches 7.4cd / A. Compared with the current efficiency of 5.3cd / A in Example 2 without an insertion layer, the current efficiency of device 3 in Example 3 is increased by about 40%, showing a better effect.
[0066] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.
Claims
1. An organic light emitting diode device, characterized in that: It comprises a stacked anode, a hole injection layer, a donor material layer, an acceptor material layer, an electron injection layer and a cathode; the donor material layer contains a donor material; the acceptor material layer contains an acceptor material; the difference between the absolute value of the LUMO energy level of the donor material and the LUMO energy level of the acceptor material is ≥0.4eV.
2. The organic light emitting diode device according to claim 1, characterized in that: The singlet energy level S1-(triplet energy level T1×2 of the donor material) of the donor material is ≤0.2 eV.
3. The organic light emitting diode device according to claim 1 or 2, characterized in that: The donor material is selected from rubrene materials, and the acceptor material is selected from fullerene materials; the thickness of the donor material layer is 5 to 50 nm; the thickness of the acceptor material layer is 5 to 50 nm.
4. The organic light emitting diode device according to claim 1, characterized in that: The singlet energy level S1-(triplet energy level T1×2) of the acceptor material is ≤ 0.2 eV.
5. The organic light emitting diode device according to claim 1 or 4, characterized in that: The acceptor material is selected from at least one of pyrene compounds, phenanthrene compounds and anthracene compounds; the donor material is selected from hole-type materials; the hole mobility of the hole-type material is greater than the electron mobility; the thickness of the donor material layer is 5 to 50 nm; the thickness of the acceptor material layer is 5 to 50 nm.
6. The organic light emitting diode device according to claim 1, characterized in that: The organic electroluminescent diode device further comprises a spacer layer; the spacer layer is located between the donor material layer and the acceptor material layer.
7. The organic light emitting diode device according to claim 6, characterized in that: The spacer layer contains a barrier material; the singlet energy level S1 of the barrier material is higher than the singlet energy level S1 of the donor material; the triplet energy level T1 of the barrier material is not lower than the triplet energy level T1 of the donor material; the triplet energy level T1 of the barrier material is not higher than the triplet energy level T1 of the acceptor material.
8. The organic light emitting diode device according to claim 7, characterized in that: The barrier material is a bipolar material, the hole mobility and electron mobility of which differ within an order of magnitude, and the thickness of the spacer layer is 1-10 nm.
9. The organic light emitting diode device according to claim 1, characterized in that: The organic electroluminescent diode device further comprises a hole transport material layer and / or an electron transport material layer; the hole transport material layer is located between the hole injection layer and the donor material layer; the electron transport material layer is located between the acceptor material layer and the electron injection layer.
10. Use of the organic light emitting diode device according to any one of claims 1 to 9 in light emitting electronic products.