A white organic light emitting device using blue light material and platinum or palladium aggregate state light emitting and application thereof

Abstract

This invention provides a white OLED device utilizing blue light-emitting materials and platinum or palladium aggregated-state emission, comprising: a cathode, an anode, and an organic functional layer including at least two emission layers, including a blue light layer and a low-energy emission layer. The blue light layer comprises a first matrix material doped with Ir(III) organometallic complexes, and the low-energy emission layer comprises a second matrix material comprising Pt(II) and / or Pd(II) organometallic complexes. When a DC voltage higher than its turn-on voltage is applied, the device emits white light composed of monomeric and aggregated-state emission from the blue emitter and the low-energy platinum complex. This white OLED device eliminates the need for a blue light emitter, achieving a high CRI with only a single emitter.

Description

Technical Field

[0001] This invention relates to a white OLED device that utilizes blue light-emitting materials and platinum or palladium aggregated states to emit light, and its applications. Background Technology

[0002] Organic light-emitting diodes (OLEDs), as a next-generation display technology, possess a series of excellent properties, including self-illumination, no need for backlight modules, high contrast and clarity, wide viewing angle, all-solid-state operation, suitability for flexible panels, good temperature characteristics, low power consumption, fast response speed, and low manufacturing cost. They have been widely used in industries such as flat panel displays, flexible displays, solid-state lighting, and automotive displays. However, simultaneously achieving high efficiency and a high color rendering index has remained a bottleneck and a hot topic in OLED research.

[0003] OLED devices typically employ a sandwich structure consisting of a cathode, an anode, and an organic functional layer. The organic functional layer primarily comprises a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). Additionally, in top-emitting devices, a light extraction layer (CPL) is usually introduced outside the cathode. When a DC bias is applied, holes are injected from the anode and transferred to the emissive layer via the highest occupied molecular orbital (HOMO), while electrons are injected from the cathode and transferred to the emissive layer via the lowest unoccupied molecular orbital (LUMO). Electrons and holes recombine in the emissive layer to generate excitons; when these excitons release energy in the form of light radiation, it constitutes electroluminescence. The selection of organic functional layer materials is crucial in the fabrication and optimization of OLEDs, as their properties are a key factor determining device performance.

[0004] Based on different light-emitting mechanisms, OLED materials can be classified into fluorescent materials, phosphorescent materials, triplet-triplet annihilation (TTA) materials, and thermally activated delayed fluorescence (TADF) materials.

[0005] Chelates and organometallic compounds are used as functional materials in many different types of applications. In organic-component-based OLED devices, the use of organometallic complexes with phosphorescence rather than fluorescence has been increasingly discussed. Due to theoretical spin statistics, using organometallic compounds as phosphorescent emitters can improve energy and power efficiency by up to four times. Their main advantages, making them particularly suitable for practical applications, are long operating lifetime, high temperature stress stability, and low operating voltage for mobile applications.

[0006] Many known metal complexes have low thermal stability and inevitably release organic pyrolysis products once vacuum deposited, thus significantly shortening the operating life of OLEDs (RG Charles, J. Inorg. Nucl. Chem., 1963, 25, 45).

[0007] It is known that metal complexes of group 10 transition metals (Ni, Pd, Pt) exhibit electroluminescence in the blue, red, and green regions. The central metal atom is bonded via two aromatic N atoms and two C atoms, or via two imine N atoms and two phenolic O atoms, or via two aromatic N atoms and two basic N atoms.

[0008] However, there is still a demand in the industry for white OLED devices with high color rendering index (CRI), high efficiency, and strong thermal stability. Summary of the Invention

[0009] Therefore, the purpose of this invention is to provide a white OLED device that utilizes blue light materials and platinum aggregated states to emit light, as well as its preparation method and application.

[0010] This invention provides a white OLED device utilizing blue light-emitting materials and platinum or palladium aggregated-state emission, comprising: a cathode, an anode, and an organic functional layer including at least two light-emitting layers. The at least two light-emitting layers include a blue light-emitting layer and a low-energy light-emitting layer. The blue light-emitting layer comprises a first matrix material doped with Ir(III) organometallic complexes, and the low-energy light-emitting layer comprises a second matrix material doped with Pt(II) organometallic complexes and / or Pd(II) organometallic complexes. The emission wavelength of the Ir(III) organometallic complexes is between 460 and 500 nm. The Pt(II) and Pd(II) organometallic complexes have at least two emission modes: monomeric and aggregated states. The emission wavelength of the monomeric state is between 500 and 550 nm, and the emission wavelength of the aggregated state is between 560 and 690 nm. At least one light-emitting layer employs a dual-host material.

[0011] According to the white OLED device provided by the present invention, the Ir(III) organometallic complex can be any Ir(III) organometallic complex known in the art capable of emitting blue light, for example, it can be one or more of bis(4,6-difluorophenylpyridine-N,C2)pyridinecarboxyiridium (FIrpic), bis(4,6-difluorophenylpyridine)-(3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazole)iridium (FIrtaz), and bis(4,6-difluorophenylpyridine)(5-(pyridin-2-yl)-tetraazole)iridium (FIrN4).

[0012] Preferably, in the blue light layer, the Ir(III) organometallic complex is mixed with the first matrix material at a content of 1-10 wt%, more preferably 1-6 wt%. The first matrix material preferably transports holes and / or electrons and has a wider band gap than the Ir(III) organometallic complex. In a preferred embodiment of the invention, the first matrix material may be an organic compound, such as, but not limited to, one or more of the following: compound MCP of Formula I, compound B3PYMPM of Formula II, DMIC-TRZ (Formula A), DMIC-CZ (Formula B), 3,3′-bis(9H-carbazol-9-yl)-1,1′-biphenyl (MCBP), and MCP-cn (Formula C).

[0013]

[0014] In a preferred embodiment, the first matrix material is a mixture of two main materials, with a preferred molar ratio of 1:0.5 to 2. More preferably, the first matrix material is a mixture of MCP and B3PYMPM, wherein the molar ratio of MCP:B3PYMPM is 1:0.5 to 2, more preferably 1:0.8 to 1.2.

[0015] According to the white OLED device provided by the present invention, preferably, the Pt(II) organometallic complex and the Pd(II) organometallic complex are selected from compounds represented by Formula III:

[0016]

[0017] M, CY1, CY2, Rn, Rm, R1, R2, R3, R4, R5, and R6 are defined as follows:

[0018] (a) M is either Pt or Pd;

[0019] (b) CY1 is selected from pyridine rings, 5-membered rings, 6-membered rings, nitrogen heterocycles or thioheterocycles, or their derivatives;

[0020] (c)CY2 is selected from 5-membered rings, 6-membered rings, nitrogen heterocycles or oxygen bridges, or their derivatives;

[0021] (d) Rn and Rm are respectively attached to a CY1 ring or a CY2 group; wherein Rn and Rm are selected from straight-chain or branched C groups having at least one functional group. 1～8 hydrocarbon group;

[0022] (e) R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen or C. 1～20 Straight-chain or branched alkyl groups.

[0023] More preferably, the low-energy light-emitting layer comprises a second matrix material doped with a Pt(II) organometallic complex, wherein the Pt(II) organometallic complex is the compound Tetra-Pt-2 represented by Formula IV, where tBu represents tert-butyl.

[0024]

[0025] Preferably, in the low-energy light-emitting layer, the Pt(II) organometallic complex and / or Pd(II) organometallic complex are mixed with the second matrix material at a content of 10-30 wt%, more preferably 15-25 wt%. The second matrix material preferably transports holes and / or electrons and has a wider band gap than the organometallic complex in this invention. The second matrix material can be an organic compound, for example, but not limited to, one or more of the following: compound TCTA of formula V, compound B3PYMPM of formula II, compound PO-T2T of formula VI, 4,6-bis(3,5-di(4-pyridinylphenyl)-2-methylpyrimidine (B4PYMPM), compound DMIC-TRZ of formula A, and compound DMIC-CZ of formula B.

[0026]

[0027] According to the white OLED device provided by the present invention, the thickness of the blue light layer can be 5-15 nm, preferably 6-8 nm. The thickness of the low-energy layer can be 2-10 nm, preferably 5-7 nm.

[0028] In a preferred embodiment of the present invention, the organic functional layer may include two blue light-emitting layers, the two blue light-emitting layers being made of the same or different materials. Preferably, the two blue light-emitting layers are respectively arranged on both sides of the low-energy light-emitting layer, forming a "sandwich" structure.

[0029] In a preferred embodiment of the present invention, in addition to the blue light layer and the low-energy layer, the organic functional layer may further include one or more of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. In a preferred embodiment, the hole injection layer is the compound HAT-CN represented by Formula VII. In a preferred embodiment, the electron transport layer is the compound TMPYPB represented by Formula VIII.

[0030]

[0031] In some implementations, the organic functional layer of the white OLED device may also contain other organic compounds, metals, or metal compounds as dopants.

[0032] The present invention also provides a method for fabricating the above-mentioned white OLED device, wherein the fabrication method includes forming the blue light layer and the low energy layer on a substrate by one or more methods such as vacuum evaporation, spin coating, printing and printing.

[0033] The present invention also provides a light source device, wherein the light source device includes the white OLED device provided by the present invention.

[0034] The present invention also provides an apparatus including the white OLED device of the present invention, the apparatus comprising a fixed visual display unit, a mobile visual display unit, an illumination unit, a keyboard, clothing, furniture, and wallpaper. The apparatus may include a fixed visual display unit, a mobile visual display unit, an illumination unit, a keyboard, clothing, furniture, and wallpaper. The mobile visual display unit may be a tablet computer, a mobile phone, a laptop computer, a digital camera, a music player, a visual display unit in a vehicle, or a destination display on or inside a bus or train. Preferably, the fixed visual display unit is a visual display unit in an information panel. Preferably, the mobile visual display unit is a visual display unit in a smartphone.

[0035] The white OLED device provided by this invention emits blue light from Ir(III) complexes and low-energy light from excimer emission of Pt complexes. When a DC voltage higher than its turn-on voltage is applied to the device, it emits white light composed of blue emission and monosodium and aggregated emission from low-energy platinum complex emitters. This white OLED device utilizes monosodium and aggregated emission from platinum complexes, achieving a very high CRI (CRI can reach 86) using only two luminescent materials. Attached Figure Description

[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0037] Figure 1 The device prepared in Embodiment 1 of the present invention has a density of 100 cd / m². 2 1000cd / m 2 and 5000cd / m 2 Normalized EL spectrum at brightness;

[0038] Figure 2 The device obtained in Embodiment 2 of the present invention has a density of 100 cd / m². 2 1000cd / m 2 and 5000cd / m 2 Normalized EL spectrum at brightness;

[0039] Figure 3The figures show the brightness-external quantum efficiency (EQE) curves of the devices prepared in Examples 1 and 2 of this invention. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0041] Example 1

[0042] White OLED devices with multiple emissive layers (EMLs) were fabricated using the SPECTROS vacuum evaporation system from Kurt J. Lesker. Device 1 has the following structure:

[0043] Substrate-ITO / HAT-CN(5nm) / TAPC(40nm) / MCP(10nm) / MCP:6wt%FIrpic(EML1,8nm) / TCTA:B3PYMPM:20w t%tetra-Pt-2(EML2, 6nm) / MCP:6wt%FIrpic(EML3, 8nm) / TMPYPB(50nm) / LiF(1.2nm) / Al(100nm)

[0044] Example 2

[0045] A white OLED device with multiple EMLs was fabricated using the same method as in Example 1, except that the blue light layer used a two-component matrix material. The structure of device 2 is as follows:

[0046] Substrate-ITO / HAT-CN(5nm) / TAPC(40nm) / MCP(10nm) / MCP:B3PYMPM:6wt%FIrpic(EML1,8nm) / TCTA:B3PYMPM:20w t%tetra-Pt-2(EML2, 6nm) / MCP:B3PYMPM:6wt%FIrpic(EML3, 8nm) / B3PYMPM(50nm) / LiF(1.2nm) / Al(100nm)

[0047] Performance testing

[0048] The performance of the white OLED devices prepared in Examples 1 and 2 was tested using a Keithley 2400 power supply and a Hamamatsu Photonics C9920-12 OLED testing system. The EL spectra are as follows: Figure 1 and Figure 2 As shown, Figure 3The brightness-EQE curves of the devices are shown in Table 1. The OLED performance data are listed in Table 1.

[0049] Table 1

[0050]

[0051] Note: CIE = COMMISSION INTERNATIONALE DE L'ECLAIRAGE, i.e., the International Commission on Illumination; turn-on voltage refers to a luminance of 1 cd / m². 2 Voltage at time; CRI = Color Rendering Index

[0052] exist Figure 1 and Figure 2 In the results, the spectra of devices 1 and 2 both have three peaks, located at 470 nm, 520 nm, and 650 nm, respectively. Here, the peak at 470 nm is attributed to the emission of FIRPIC, and the emission peak at 650 nm is attributed to the excimer emission of tetra-Pt-2. However, there is a peak with very high emission intensity at 520 nm. This emission peak should be attributed to the monomer emission of tetra-Pt-2, since the doping concentration of tetra-Pt-2 is reduced to 20 wt%. Therefore, at this concentration, the monomeric and excimer states can coexist.

[0053] The spectra of devices 1 and 2 are in the range of 100–5000 cd / m 2 The brightness is relatively stable. As shown in Table 1, the CIE coordinate of device 1 is 100 cd / m. 2 At (0.52, 0.43); while at 1000 cd / m 2 At that time, the CIE coordinates only change to (0.50, 0.45); even at 5000 cd / m 2 At high brightness, the CIE coordinates are (0.48, 0.46). Device 1 has a CRI of 85, which meets the requirements for general white light. However, device 1 has limitations at 1000 cd / m². 2 The CIE coordinates at that time were outside the white light region of the CIE color chart; it actually belonged to the yellow light region.

[0054] For device 2, the CIE coordinates are at 100 cd / m. 2 1000cd / m 2 and 5000cd / m 2 The coordinates are (0.52, 0.42), (0.48, 0.43), and (0.47, 0.43), respectively. The CIE coordinates are at 1000 cd / m. 2 and 5000cd / m 2 Both are located in the warm white area of ​​the CIE color diagram. Device 2 is at 1000 cd / m². 2The CRI is as high as 86, which can meet the requirements of general lighting.

[0055] like Figure 3 As shown in Table 1, compared with device 2, device 1's EQE max Higher, at 16.7%. (For device 2, EQE) max =16.4%) Even at 100 cd / m 2 At the same brightness, device 1 also outperforms device 2 in terms of EQE. This is likely due to the higher triplet energy of the matrix material MCP. However, device 1 exhibits lower EQE in the range of 1000–5000 cd / m². 2 At actual high brightness levels, the efficiency of the matrix material will decrease. At 1000 cd / m², this is a concern. 2 At that time, its EQE 1000 It can maintain 15.5%, but at 5000 cd / m 2 At that time, EQE 5000 It dropped to 8.9%.

[0056] In comparison, the EQE of device 2 1000 It can maintain 16.1%, while EQE 5000 It can still reach 13.2%, which is much higher than the EQE of device 1. 1000 This is attributed to the composite matrix material structure of EML1 and EML3, which can broaden the exciton recombination region and suppress TTA quenching (triplet-triplet quenching).

Claims

1. A white OLED device utilizing blue light-emitting materials and platinum or palladium aggregated states to emit light, comprising: The device comprises a cathode, an anode, and an organic functional layer including at least two light-emitting layers, wherein the at least two light-emitting layers include a blue light-emitting layer and a low-energy light-emitting layer, the blue light-emitting layer comprising a first matrix material doped with Ir(III) organometallic complexes, and the low-energy light-emitting layer comprising a second matrix material doped with Pt(II) organometallic complexes and / or Pd(II) organometallic complexes, wherein the emission wavelength of the Ir(III) organometallic complexes is between 460 and 500 nm; the Pt(II) organometallic complexes and Pd(II) organometallic complexes have at least two light-emitting forms, namely monomeric and aggregated states, wherein the emission wavelength of the monomeric state is between 500 and 550 nm, and the emission wavelength of the aggregated state is between 560 and 690 nm; At least one of the light-emitting layers uses a dual-substrate material; The Ir(III) organometallic complex is one or more of bis(4,6-difluorophenylpyridine-N,C2)pyridinecarboxylated iridium, bis(4,6-difluorophenylpyridine)-(3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazole)iridium, and bis(4,6-difluorophenylpyridine)(5-(pyridin-2-yl)-tetraazole)iridium; The Pt(II) organometallic complex and Pd(II) organometallic complex are selected from compounds represented by Formula III: Formula III M, CY1, CY2, Rn, Rm, R1, R2, R3, R4, R5, and R6 are defined as follows: (a) M is either Pt or Pd; (b) CY1 is selected from pyridine rings, 5-membered rings, 6-membered rings, nitrogen heterocycles or thioheterocycles, or their derivatives; (c)CY2 is selected from 5-membered rings, 6-membered rings, nitrogen heterocycles or oxygen bridges, or their derivatives; (d) Rn and Rm are respectively attached to a CY1 ring or a CY2 group; wherein Rn and Rm are selected from straight-chain or branched C groups having at least one functional group. 1-8 hydrocarbon group; (e) R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen or C. 1-20 Straight-chain or branched alkyl groups.

2. The white OLED device according to claim 1, wherein, The first matrix material is one or more of the following: compound MCP of Formula I, compound B3PYMPM of Formula II, compound DMIC-TRZ of Formula A, compound DMIC-CZ of Formula B, 3,3′-bis(9H-carbazol-9-yl)-1,1′-biphenyl, and compound MCP-cn of Formula C. Formula I Formula II Formula A Formula B Formula C.

3. The white OLED device according to claim 1, wherein, In the blue light layer, the Ir(III) organometallic complex is mixed with the first matrix material at a content of 1-10 wt%.

4. The white OLED device according to claim 3, wherein, In the blue light layer, the Ir(III) organometallic complex is mixed with the first matrix material at a content of 1-6 wt%.

5. The white OLED device according to claim 2, wherein, The first matrix material is a mixture of two main materials.

6. The white OLED device according to claim 5, wherein, The molar ratio of the two main materials is 1:0.5-2.

7. The white OLED device according to claim 5, wherein, The first matrix material is a mixture of MCP and B3PYMPM, wherein the molar ratio of MCP to B3PYMPM is 1:0.5-2.

8. The white OLED device according to claim 7, wherein, The molar ratio of MCP to B3PYMPM is 1:0.8-1.

2.

9. The white OLED device according to claim 1, wherein, The low-energy light-emitting layer comprises a second matrix material doped with a Pt(II) organometallic complex, wherein the Pt(II) organometallic complex is the compound Tetra-Pt-2 represented by Formula IV, where tBu represents tert-butyl. Formula IV.

10. The white OLED device according to claim 1, wherein, The second matrix material is one or more of the following: compound TCTA (Formula V), compound B3PYMPM (Formula II), compound PO-T2T (Formula VI), 4,6-bis(3,5-di(4-pyridylphenyl)-2-methylpyrimidine, compound DMIC-TRZ (Formula A), and compound DMIC-CZ (Formula B). Formula V and Formula II Formula VI Formula A Formula B.

11. The white OLED device according to claim 1, wherein, In the low-energy light-emitting layer, the Pt(II) organometallic complex and / or Pd(II) organometallic complex are mixed with the second matrix material at a content of 10-30 wt%.

12. The white OLED device according to claim 11, wherein, In the low-energy light-emitting layer, the Pt(II) organometallic complex and / or Pd(II) organometallic complex are mixed with the second matrix material at a content of 15-25 wt%.

13. The white OLED device according to claim 11, wherein, The second matrix material is a mixture of TCTA and B3PYMPM, wherein the molar ratio of TCTA to B3PYMPM is 1:0.5-2.

14. The white OLED device according to claim 13, wherein, The molar ratio of TCTA to B3PYMPM is 1:0.8-1.

2.

15. The white OLED device according to any one of claims 1 to 14, wherein, The thickness of the blue light layer is 5-15 nm.

16. The white OLED device according to claim 15, wherein, The thickness of the blue light layer is 6-8 nm.

17. The white OLED device according to any one of claims 1 to 14, wherein, The thickness of the low-energy light-emitting layer is 2-10 nm.

18. The white OLED device according to claim 17, wherein, The thickness of the low-energy light-emitting layer is 5-7 nm.

19. A method for fabricating a white OLED device according to any one of claims 1 to 18, the method comprising forming the blue light layer and the low energy light-emitting layer on a substrate using one or more methods selected from vacuum evaporation, spin coating, printing and printing.

20. A light source device, wherein, The light source device includes the white OLED device according to any one of claims 1 to 18.

21. An apparatus comprising a white OLED device according to any one of claims 1 to 18, the apparatus comprising a fixed visual display unit, a movable visual display unit, an illumination unit, a keyboard, clothing, furniture, and wallpaper.

22. The apparatus according to claim 21, wherein, The mobile visual display unit is one of a tablet computer, mobile phone, laptop computer, digital camera, music player, visual display unit in a vehicle, and destination display on or inside a bus or train.

23. The apparatus according to claim 22, wherein, The mobile visual display unit is the visual display unit of a smartphone.

24. The apparatus according to claim 21, wherein, The fixed visual display unit is the visual display unit in the information panel.

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