A blue luminescent compound, a blue luminescent composition, and an organic electroluminescent device, a display device, and a lighting device containing the same

Abstract

The present invention discloses a blue luminescent compound, a blue luminescent composition, and an organic electroluminescent device, a display device, and a lighting device containing the same. The blue luminescent compound is selected from one of the structures shown below. The blue luminescent compound provided by the present invention is used as a main material of a blue luminescent layer, and an α-naphthalene substituent is used to improve the triplet-triplet fusion process (TTF effect) of the material, thereby increasing the theoretical exciton utilization rate of the material to 62.5%, and improving the electron transfer rate of the material by introducing oxygen atoms with large electronegativity, thereby improving the carrier balance. Furthermore, by deuterating at least a portion of the naphthyl and anthracene nuclei, and at the same time using half-deuterated dibenzofuran, the exciton energy rise caused by vibration of the material is reduced while significantly enhancing the thermal stability of the material, thereby reducing the damage and degradation of the adjacent layer materials by the excitons, and thus significantly improving the life of the organic electroluminescent device, overcoming the defects of the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of OLED, and specifically comprises a blue light-emitting compound, a blue light-emitting composition, and an organic electroluminescent device, a display device and a lighting device comprising the same. Background Art

[0002] In the field of electroluminescent organic materials, the research and development of red and green luminescent materials are relatively sufficient. Since the energy gap of red and green luminescent materials only needs to be around 2eV to 2.4eV, which is much lower than the energy of chemical bonds of commonly used organic materials, there are a wide variety of materials to choose from. At present, red and green light basically use metal organic complexes as luminescent doping materials, and the theoretical exciton utilization rate in the luminescence process is increased to 100% through the spin-orbit coupling of heavy atoms. However, for blue light materials, since the energy gap required for blue light luminescent materials is about 3.0eV, and blue phosphorescent materials have serious efficiency roll-off and life problems and cannot be mass-produced, most of them use fluorescent materials. However, the theoretical exciton utilization rate of fluorescent material electroluminescence is only 25%, which limits the further improvement of efficiency.

[0003] Studies have found that in the process of organic electroluminescence, holes and electrons recombine into excitons in the light-emitting layer, and the excitons emit photons and then recede to the ground state. Usually, the hole transfer rate of organic materials is higher than the electron transfer rate, which makes the carrier transfer in the organic electroluminescent device unbalanced, resulting in the widening of the light-emitting area and the reduction of the exciton concentration. When the light-emitting area spreads to the carrier transport area, the excitons and polarons are easily quenched when they meet, resulting in the degradation of the carrier transport material, which seriously damages the efficiency and life of the organic electroluminescent device.

[0004] The problem with the commonly used anthracene-based host materials at present is that the anthracene core skeleton is easy to dehydrogenate and form a ring with the substituent, which causes a significant change in the luminescence performance of the material, seriously restricting the life of the organic electroluminescent material. Replacing the hydrogen in the anthracene-based host material with an isotope can improve the stability of the chemical bond, but it will greatly increase the preparation cost. At the same time, the difference in the substitution site also has different effects on the degree of improvement in the life. Some studies have claimed that only the deuterated anthracene core skeleton can achieve thermal stability equivalent to that of the fully deuterated material. However, since the host material of the luminescent layer is directly connected to the electron blocking layer or the hole transport layer, the vibration of the undeuterated carbon-hydrogen bond may further increase the energy of the composite high-energy excitons and increase the destructive effect of the excitons on the adjacent layers. Therefore, when applied to different organic light-emitting devices, there are differences in the life performance. The research on the partial deuteration of the substituent is still insufficient. At the same time, it is difficult to measure and control the uniformity of the doping ratio of the host and guest materials and the degree of the host material during the evaporation preparation process of the doping system. The uneven evaporation between the organic film layers and within the film will increase the material degradation sites and is not conducive to the device life performance. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a blue light-emitting compound, a blue light-emitting composition, and an organic electroluminescent device, a display device and a lighting device comprising the same.

[0006] To achieve the above objectives, the technical solutions adopted by the present invention include:

[0007] A first aspect of the present invention provides a blue light-emitting compound, characterized in that the blue light-emitting compound is selected from one of the following structures:

[0008]

[0009] ;

[0010] In the above structure, any oxygen can be 17 O or 18 O substitution, any carbon can be 13 C substituted.

[0011] D in the above compounds means that hydrogen is replaced by deuterium, which is present at least 100 times the natural abundance.

[0012] A second aspect of the present invention provides a blue light-emitting composition, which comprises two or more of the blue light-emitting compounds described above.

[0013] The third aspect of the present invention provides a use of the above-mentioned blue light-emitting compound or the above-mentioned composition as a main material of a blue light-emitting layer in an organic electroluminescent device.

[0014] The fourth aspect of the present invention provides an organic electroluminescent device, which includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode arranged in sequence on a substrate; wherein the light-emitting layer includes one or more blue light-emitting compounds as described above or the composition as described above.

[0015] Furthermore, the light-emitting layer includes a host material and a guest material, wherein the light-emitting layer includes a host material and a guest material, wherein the host material includes one or more of the blue light-emitting compounds as described above or the combination as described above.

[0016] A fourth aspect of the present invention provides a display device, comprising the organic electroluminescent device as described above.

[0017] A fifth aspect of the present invention provides a lighting device, comprising the organic electroluminescent device as described above.

[0018] Beneficial effects of the present invention:

[0019] The present invention provides a blue light-emitting compound as a main material of a light-emitting layer of a blue organic electroluminescent device. The blue light-emitting compound provided by the present invention can improve the triplet-triplet fusion process (TTF effect) of the material by using an α-naphthalene substituent, and improve the theoretical exciton utilization rate of the material to 62.5%. The electron transfer rate of the material can be improved by introducing oxygen atoms with large electronegativity, so that the transmission of carriers in the organic electroluminescent device can be balanced. Furthermore, the blue light-emitting compound provided by the present invention deuterates at least a part of the naphthyl and anthracene nuclei, and is combined with semi-deuterated dibenzofuran, so that the thermal stability of the material can be significantly enhanced, and the exciton energy rise caused by vibration of the material can be significantly reduced, thereby reducing the damage and degradation of the adjacent layer materials by the excitons, and further significantly improving the life of the organic electroluminescent device, thereby overcoming the defects of the prior art.

[0020] The present invention also provides a blue light-emitting composition as a main material of a light-emitting layer of a blue organic electroluminescent device. The blue light-emitting composition provided by the present invention comprises two blue light-emitting compounds with different deuterium substitution sites. The two main materials with different deuterium substitution sites are used as the main body of the light-emitting layer, which can be used as a stable co-evaporation source in a vacuum deposition process, and can improve the film formation of the organic layer of the device and thus improve the life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the organic electroluminescent device of the present invention.

[0022] In the figure: 1-substrate, 2-anode, 3-hole injection layer, 4-hole transport layer, 5-luminescence auxiliary layer, 6-luminescent layer, 7-hole blocking layer, 8-electron transport layer, 9-electron injection layer, 10-cathode. DETAILED DESCRIPTION

[0023] In order to more clearly understand the content of the present invention, it will be described in detail with reference to the drawings and embodiments.

[0024] The compounds of the present invention are suitable for use in light-emitting elements, display panels and electronic devices, and are particularly suitable for use in organic electroluminescent devices. The electronic device described in the present invention is a device comprising a layer of at least one organic compound, and the device may also comprise an inorganic material or a layer formed entirely of an inorganic material. The electronic device is preferably an organic electroluminescent device (OLED), an organic integrated circuit (O-IC), an organic field effect transistor (O-FET), an organic thin film transistor (O-TFT), an organic light-emitting transistor (O-LET), an organic solar cell (O-SC), an organic dye-sensitized solar cell (O-DSSC), an organic optical detector, an organic photoreceptor, an organic field quenching device (O-FQD), a light-emitting electrochemical cell (LEC), an organic laser diode (O-laser) and an organic plasma emission device. The electronic device is preferably an organic electroluminescent device (OLED). The structural schematic diagram of an exemplary organic electroluminescent device is shown in FIG. Figure 1 shown.

[0025] Experimental Section

[0026] In order to understand the content of the present invention more clearly, the polycyclic compound, the preparation method of the compound and the luminescent characteristics of the device will be explained in detail in conjunction with the examples. Various chemical reactions can be applied to the synthetic method of the compound of an embodiment of the present invention. However, it should be noted that the synthetic method of the compound of an embodiment of the present invention is not limited to the synthetic method described below. Unless otherwise indicated, the subsequent synthesis is carried out in anhydrous solvent under a protective gas atmosphere. Solvents and reagents can be purchased from conventional reagent suppliers.

[0027] Synthesis Example 1

[0028]

[0029] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol and 25 mL of water were added under nitrogen protection, and then A01 (3.98 g, 10 mmol), B01 (2.16 g, 10 mmol), potassium carbonate (4.15 g, 30 mmol) and tetrakistriphenylphosphine palladium (0.35 g, 0.3 mmol) were added, and the mixture was heated to 80 °C for 12 h. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was dissolved in toluene and then filtered to remove the solid insoluble matter. It was then recrystallized to obtain compound BH01: 4.08 g (yield: 83%), MS: m / z (M+): 491.

[0030] Synthesis Example 2

[0031]

[0032] The preparation method is the same as that of Synthesis Example 1, except that A02 (3.91 g; 10 mmol) and B02 (2.16 g; 10 mmol) replace A01 and B01, and the final product BH02 is 3.73 g (yield: 77%), MS (m / z) (M+): 484.

[0033] Synthesis Example 3

[0034]

[0035] The preparation method is the same as that of Synthesis Example 1, except that A03 (3.9 g; 10 mmol) and B03 (2.16 g; 10 mmol) replace A01 and B01, and finally the product BH03 is obtained: 3.77 g (yield: 78%), MS (m / z) (M+): 483.

[0036] Synthesis Example 4

[0037]

[0038] The preparation method is the same as that of Synthesis Example 1, except that A04 (3.98 g; 10 mmol) and B04 (2.15 g; 10 mmol) replace A01 and B01, and the final product BH04 is 4.12 g (yield: 84%), MS (m / z) (M+): 490.

[0039] Synthesis Example 5

[0040]

[0041] The preparation method is the same as that of Synthesis Example 1, except that A05 (3.91 g; 10 mmol) and B05 (2.15 g; 10 mmol) replace A01 and B01, and finally the product BH05 is obtained: 3.77 g (yield: 78%), MS (m / z) (M+): 483.

[0042] Synthesis Example 6

[0043]

[0044] The preparation method is the same as that of Synthesis Example 1, except that A06 (3.9 g; 10 mmol) and B06 (2.15 g; 10 mmol) replace A01 and B01, and finally the product BH06 is obtained: 3.9 g (yield: 81%), MS (m / z) (M+): 482.

[0045] Comparative Example Compound

[0046] .

[0047] Fabrication and characterization of OLEDs

[0048] Device Embodiment

[0049] The organic electroluminescent device provided by the present invention comprises an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode which are sequentially arranged on a substrate;

[0050] Furthermore, the hole transport region includes a hole injection layer, a hole transport layer and a light-emitting auxiliary layer; and the electron transport region includes an electron transport layer and an electron injection layer.

[0051] Furthermore, the light-emitting layer is composed of a host material and a guest material, and the host material of the light-emitting layer can be composed of one molecular material or multiple molecular materials.

[0052] The composition of the present invention can be used for the light-emitting layer of the above-mentioned organic electroluminescent device.

[0053] The anode in the embodiment adopts anode materials commonly used in the art, such as ITO, Ag or their multilayer structures. The hole injection layer adopts hole injection materials commonly used in the art, and F4TCNQ, HATCN, NDP-9, etc. are added for doping. The hole transport layer adopts hole transport materials commonly used in the art. The light-emitting layer adopts the host and guest material composition provided by the present invention. The electron transport layer adopts electron transport materials commonly used in the art. The electron injection layer adopts electron injection materials commonly used in the art, such as Liq, LiF, Yb, etc. The cathode adopts materials commonly used in the art, such as metal Al, Ag or metal mixtures (Ag-doped Mg, Ag-doped Ca, etc.).

[0054] The electrode preparation method and the deposition method of each functional layer in this embodiment are conventional methods in the art, such as vacuum thermal evaporation or inkjet printing, etc., which will not be described in detail here. Only some process details and test methods in the preparation process are supplemented as follows:

[0055] Device Example 1

[0056] The substrates used in the present invention were subjected to the following operations: the ITO substrate was patterned so that its luminous area had a size of 3 mm×3 mm, and then water / isopropanol ultrasound, UV / ozone irradiation, and then dried at 100°C. After that, the ITO substrate was mounted on a substrate holder of a vacuum deposition device and the pressure was adjusted so that the vacuum rate became 1×10 -7 torr. Then the following operations were performed: first, on the ITO layer (anode) formed on the substrate, HT01 and PD01 (the mass ratio of HT01 to PD01 was 97:3) were vacuum deposited with a thickness of 10 nm to form a hole injection layer; secondly, on the hole injection layer, HT01 was vacuum deposited with a thickness of 120 nm to form a hole transport layer; secondly, on the hole transport layer, BP01 was vacuum deposited with a thickness of 5 nm to form an electron blocking layer; secondly, on the electron blocking layer, a mixture of BH01 and BD01 provided by the present invention was vacuum deposited with a thickness of 20 nm to form a light-emitting layer, wherein BH01 was used as a host material and BD01 was used as a guest material, and the mass ratio of the host material to the guest material was 98:2; then, on the light-emitting layer, HB01 was vacuum deposited with a thickness of 5 nm to form a hole blocking layer; then, on the above-mentioned vacuum On the hole blocking layer, ET01 and LiQ (the mass ratio of ET01 to LiQ is 1:1) are vacuum deposited with a thickness of 20nm to form an electron transport layer; then on the above electron transport layer, Yb is vacuum deposited with a thickness of 1nm to form an electron injection layer, and then on the above electron injection layer, Mg / Ag (the mass ratio of Mg to Ag is 1:9) is deposited with a thickness of 15nm to form a cathode, and then on the above cathode, CP01 is deposited with a thickness of 50nm to form a covering layer. Finally, the vapor-deposited substrate is packaged, and the cleaned cover plate is coated with UV glue using a glue coating equipment, and then the coated cover plate is moved to the pressing section, and the vapor-deposited substrate is placed on the upper end of the cover plate. Finally, the substrate and the cover plate are bonded under the action of the bonding equipment, and the UV glue is light-cured at the same time to prepare a top-emitting organic electroluminescent device.

[0057] Except for the host and guest materials of the light-emitting layer, the molecular structures of the materials in the remaining layers are as follows:

[0058]

[0059]

[0060] Device Examples 2-6

[0061] The above method is used to prepare organic electroluminescent devices from the compounds described in other embodiments in Table 1, specifically, blue light organic electroluminescent device embodiments 2-6 are prepared by replacing BH01 in device embodiment 1 with the host materials shown in the embodiments in Table 1.

[0062] Device Examples 7-9

[0063] The above method is used to prepare organic electroluminescent devices from the compounds described in other embodiments in Table 1, specifically, blue light organic electroluminescent device embodiments 7-9 are prepared by replacing BH01 in device embodiment 1 with the host materials shown in the embodiments in Table 1.

[0064] Device Comparison Examples 1-14

[0065] The above method is used to prepare organic electroluminescent devices from the compounds described in the comparative examples in Table 1, specifically, blue light organic electroluminescent device comparative examples 1-14 are prepared by replacing BH01 in device example 1 with the host material compositions shown in the comparative examples in Table 1.

[0066] The OLED devices described above were tested by standard methods. For this purpose, at J = 10 mA / cm 2 The driving voltage and luminous efficiency of the organic electroluminescent device are determined at a current density of J = 20 mA / cm 2 When working under LT95, the luminous brightness drops to 95% of its initial value L0 after time LT95.

[0067] The test instruments and methods for testing the performance of the OLED devices in the above embodiments and comparative examples are as follows:

[0068] The luminous efficiency CE (cd / A) and color coordinates (CIEy) were tested using a spectrum scanner PhotoResearch PR-635;

[0069] Current density and lighting voltage: tested using a digital source meter Keithley 2400;

[0070] The luminous efficiency of blue light devices is greatly affected by chromaticity. The industry generally uses BI value as the basis for the efficiency of blue light devices. BI (Blue index) is obtained by dividing the luminous efficiency CE (cd / A) by the color coordinate (CIEy);

[0071] Life test: Use silicon photoelectric OLED device life test system.

[0072] The performance test results of the above devices are listed in Table 1.

[0073] Table 1 Blue-light device performance test results

[0074]

[0075] It can be seen from the above table that the present invention can achieve a life improvement effect equivalent to that of a full-deuterated compound by introducing deuterium at key sites of dibenzofuran, such as the device containing BH01 and BH04 has a lifespan substantially equivalent to that of a device containing full-deuterium DBL01, the device containing BH02 and BH05 has a lifespan substantially equivalent to that of a device containing anthracene and dibenzofuran fully deuterated DBL05, and the device containing BH03 and BH06 has a lifespan substantially equivalent to that of a device containing naphthalene and full-deuterated dibenzofuran DBL08, indicating that the compounds of the present invention can improve the stability of the material after deuterium is introduced at specific sites, especially that half-deuterated dibenzofuran can achieve the device lifespan effect of fully deuterated segments of the same device.

[0076] In particular, it can be seen that the life of the device embodiment 1 of the present invention is significantly improved when compared with the device comparative examples 2 and 3, indicating that when the degree of deuteration of the condensed ring part is the same but undeuterated dibenzofuran or dibenzofuran with too little deuteration is used, the same life improvement effect as that of full deuteration cannot be obtained. Compared with DBL04 which only has half-deuterated dibenzofuran and the condensed ring part is not deuterated, the device life is significantly improved, indicating that the improvement of the device life by only using half-deuterated benzofuran is limited. Although the half-deuterated dibenzofuran improves the stability of the main material itself to a certain extent, the lack of deuteration of the condensed ring part may make the main material in the excited state have a higher energy, which makes the degradation effect on the adjacent layer materials obvious, thereby showing a poor life performance.

[0077] By comparing BH02 with DBL06, DBL07 and DBL04, comparing BH03 with DBL09, DBL10 and DBL04, comparing BH04 with DBL11, DBL03 and DBL12, comparing BH05 with DBL13, DBL03 and DBL12, and comparing BH06 with DBL14, DBL03 and DBL12, similar conclusions can be drawn, that is, when the degree of deuteration of the naphthyl and anthracene core skeletons is the same, the life of the present invention is improved compared with the control examples in which the dibenzofuran part is not deuterated or all specific sites are not deuterated. Compared with the materials of DBL04 and DBL12 in which only half-deuteration is performed on dibenzofuran, the deuteration of the anthracene core or naphthyl of the present invention also greatly improves the life of the device, indicating that the compound of the present invention can achieve a life improvement effect equivalent to that of the full-deuterated compound by only using fewer deuterium atoms.

[0078] Compared with DBL01, the lifespan of Example 7 using a dual-body is basically equivalent to that of the fully deuterated material and is also improved compared with that using only one body. This is because the use of a dual-body stable co-evaporation is beneficial to the film formation process of the evaporation process, reducing the defects between the organic film layer and the film gap, thereby reducing the material degradation sites and improving the lifespan performance of the device.

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A blue luminescent compound, characterized in that: The blue light-emitting compound is selected from one of the following structures: 。 2. A blue light-emitting composition, characterized in that: The composition comprises two or more blue light-emitting compounds as claimed in claim 1.

3. Use of the blue light-emitting compound as described in claim 1 or the blue light-emitting composition as described in claim 2 as a main material of a blue light-emitting layer in an organic electroluminescent device.

4. An organic electroluminescent device, characterized in that: It includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode which are sequentially arranged on a substrate; wherein the light-emitting layer includes the blue light-emitting compound as claimed in claim 1 or the blue light-emitting composition as claimed in claim 2.

5. The organic electroluminescent device according to claim 4, characterized in that: The light-emitting layer includes a host material and a guest material, wherein the host material includes at least one of the blue light-emitting compounds according to claim 1 or the blue light-emitting composition according to claim 2.

6. A display device, characterized in that: Comprising the organic electroluminescent device as claimed in claim 4 or 5.

7. A lighting device, characterized in that: Comprising the organic electroluminescent device as claimed in claim 4 or 5.

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