Blue light OLED device, display panel and display device

Abstract

The present invention provides a blue light OLED device, a display panel and a display apparatus. The blue light OLED device includes a blue light emitting layer, the blue light emitting layer includes a blue light emitting main body (BH) and a blue light dopant (BD), wherein the HOMO energy level difference between the blue light emitting main body and the blue light dopant is less than or equal to 0.9 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 6%. As a result, the HOMO of the blue light dopant is not much different from the HOMO of the blue light emitting main body, and the blue light dopant will not cause a significant decrease in hole mobility due to capturing too many holes, so the blue light dopant can effectively extend the life of the blue light OLED device under the above-mentioned doping ratio.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a blue light OLED device, a display panel and a display apparatus. Background Art

[0002] At present, the blue light emitting materials in blue light OLED devices need to emit blue light. The blue light emitting materials include the blue light emitting main body BH and the blue light dopant BD. The HOMO energy level (highest molecular occupied orbital) and LUMO (lowest unoccupied molecular orbital) energy levels of the commonly used BD materials are both shallow. Therefore, in blue light OLED devices, BD is doped into BH. Since the HOMO energy level of BD is shallow, it will form a hole trap, causing the overall hole mobility of the light-emitting layer to decrease rapidly. The hole mobility of BH is usually smaller than the electron mobility. Therefore, after the shallow HOMO energy level BD is doped, the mobility difference between holes and electrons in the light-emitting layer will be further enlarged, which will cause the exciton recombination area to be biased to one side, reducing the life of the blue light OLED device.

[0003] Therefore, research on blue light OLED devices needs to be further deepened. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a blue light OLED device having a long service life.

[0005] In one aspect of the present invention, the present invention provides a blue light OLED device. According to an embodiment of the present invention, the blue light OLED device includes a blue light emitting layer, the blue light emitting layer includes a blue light emitting host (BH) and a blue light dopant (BD), wherein the HOMO energy level difference between the blue light emitting host and the blue light dopant is less than or equal to 0.9 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 6%. As a result, the HOMO of the blue light dopant is not much different from the HOMO of the blue light emitting host, and the blue light dopant will not cause a significant decrease in hole mobility due to capturing too many holes, so the blue light dopant can effectively extend the life of the blue light OLED device under the above-mentioned doping ratio.

[0006] According to an embodiment of the present invention, the HOMO energy level difference between the blue light emitting host and the blue light dopant is greater than 0.4 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 3%.

[0007] According to an embodiment of the present invention, the HOMO energy level difference between the blue light emitting host and the blue light dopant is greater than 0.6 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 2%.

[0008] According to an embodiment of the present invention, the HOMO energy level difference between the blue light emitting host and the blue light dopant is less than or equal to 0.4 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 6%.

[0009] According to an embodiment of the present invention, the chemical structural formula of the blue light emitting host is

[0010]

[0011] Wherein, Ar1, Ar2 and R are each independently hydrogen, substituted or unsubstituted C6-C30 aryl, heteroaryl or biphenyl.

[0012] According to an embodiment of the present invention, the chemical structural formula of the blue light emitting host is

[0013]

[0014] According to the embodiments of the present disclosure, the blue light emitting host satisfies at least one of the following conditions: the HOMO energy level is -6.2 to -5.3 eV; the LUMO energy level is -2.5 to -3.2 eV; the hole mobility is 1*10 -7 ~1*10 -10 ; The electron mobility is 1*10 -6 ~1*10 -8 .

[0015] According to an embodiment of the present invention, the chemical structural formula of the blue light dopant is

[0016]

[0017] Wherein, X and Y represent N, O or S respectively, wherein R1 and R2 are each independently a substituted or unsubstituted C6-C12 aryl or biphenyl; m, n are 0 or 1; R3, R4 and R5 are each independently hydrogen or a nitrogen-containing C6-C30 aryl, heteroaryl or biphenyl.

[0018] According to an embodiment of the present invention, the chemical structural formula of the blue light dopant is

[0019]

[0020] According to an embodiment of the present disclosure, the blue light dopant satisfies at least one of the following conditions: the HOMO energy level is -5.8 to -5.2 eV; the LUMO energy level is -2.1 to -3.1 eV;

[0021] According to an embodiment of the present disclosure, a blue light OLED device includes an anode, a hole injection layer, a hole transport layer, the blue light emitting layer, an electron injection layer, an electron transport layer and a cathode which are sequentially stacked.

[0022] In another aspect of the present invention, the present invention provides a display panel. According to an embodiment of the present invention, the display panel includes the above-mentioned blue light OLED device. As a result, the blue light OLED device of the display panel has a longer service life, thereby helping to extend the service life of the display panel. Those skilled in the art can understand that the display panel has all the features and advantages of the above-mentioned blue light OLED device, which will not be described in detail here.

[0023] In another aspect of the present invention, the present invention provides a display device. According to an embodiment of the present invention, the display device includes the display panel described above. The display device has a long service life and a high cost performance. Those skilled in the art can understand that the display device has all the features and advantages of the display panel described above, and no further elaboration is given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the relationship between the HOMO energy level difference between BD and BH and the BD doping ratio in one embodiment of the present invention.

[0025] Figure 2 It is a schematic structural diagram of a blue OLED device in another embodiment of the present disclosure.

[0026] Figure 3 It is a schematic diagram of the structure of a display panel in yet another embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0028] In one aspect of the present invention, the present invention provides a blue light OLED device. According to an embodiment of the present invention, the blue light OLED device includes a blue light emitting layer, the blue light emitting layer includes a blue light emitting host (BH) and a blue light dopant (BD), wherein the HOMO energy level difference between the blue light emitting host and the blue light dopant is less than or equal to 0.9 eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 6%. As a result, the HOMO of the blue light dopant is not much different from the HOMO of the blue light emitting host, and the blue light dopant will not cause a significant decrease in hole mobility due to capturing too many holes, so the blue light dopant can effectively extend the life of the blue light OLED device under the above-mentioned doping ratio.

[0029] According to the embodiments of the present invention, the inventors have found that, under the premise of ensuring a long life of the blue light OLED device, as the HOMO energy level difference between the blue light emitting host and the blue light dopant increases, the doping ratio of the blue light dopant tends to decrease, such as Figure 1 As shown (the horizontal axis is the HOMO energy level difference between the blue light emitting body and the blue light emitting body). In some embodiments, the HOMO energy level difference between the blue light emitting body and the blue light dopant is less than or equal to 0.4eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 6%; in other embodiments, the HOMO energy level difference between the blue light emitting body and the blue light dopant is greater than 0.4eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 3%; in some other embodiments, the HOMO energy level difference between the blue light emitting body and the blue light dopant is greater than 0.6eV; based on the total mass of the light emitting layer, the content of the blue light dopant is less than or equal to 2%. Under the above HOMO energy level difference and the doping ratio of the blue light dopant, the blue light OLED device has a longer lifespan.

[0030] It should be noted that the above-mentioned “HOMO energy level difference” refers to the absolute value of the HOMO energy level difference between the blue light dopant and the blue light emitting host.

[0031] According to an embodiment of the present invention, the blue light emitting host material has a core structure of anthracene, and the blue light dopant has a core structure containing boron. In this way, the blue light emitting host material containing anthracene has good electron-hole mobility and good thermal stability, and the boron-containing blue light dopant has a rigid core structure, high fluorescence quantum yield and thermal stability. Among them, by changing the substituent in the chemical structure formula of the blue light dopant, the HOMO energy level of the blue light dopant can be flexibly adjusted, and then the HOMO energy level difference between the blue light emitting host and the blue light dopant can be flexibly adjusted.

[0032] According to an embodiment of the present invention, the chemical structural formula of the blue light emitting host is

[0033]

[0034] Wherein, Ar1, Ar2 and R are each independently hydrogen, substituted or unsubstituted C6-C30 aryl, heteroaryl or biphenyl.

[0035] In some specific embodiments, the chemical structural formula of the blue light emitting host is the following chemical structural formula 1-1, chemical structural formula 1-2 and chemical structural formula 1-3:

[0036]

[0037] According to the embodiments of the present disclosure, the blue light emitting body satisfies at least one of the following conditions: the HOMO energy level is -6.2 to -5.3 eV (for example, the HOMO energy level is -6.2 eV, -6.0 eV, -5.8 eV, -5.6 eV, -5.36 eV, -5.3 eV); the LUMO energy level is -2.5 to -3.2 eV (for example, -2.5 eV, -2.6 eV, -2.7 eV, -2.8 eV, -2.9 eV, -3.0 eV, -3.1 eV, -3.2 eV); the hole mobility is 1*10 -7 ~1*10 -10 (For example, 1*10 -10 , 1*10 -9 , 5*10 -9 , 1*10 -8 , 5*10 -8 , 1*10 -7 ); the electron mobility is 1*10 -6 ~1*10 -8 (For example, 1*10 -8 , 5*10 -8 , 1*10 -7 , 5*10 -7 , 1*10 -6 ). As a result, the blue light-emitting main body has better performance, which helps to further extend the service life of the blue light OLED device.

[0038] According to an embodiment of the present invention, the chemical structural formula of the blue light dopant is

[0039]

[0040] Wherein, X and Y represent N, O or S respectively, wherein R1 and R2 are each independently a substituted or unsubstituted C6-C12 aryl or biphenyl; m, n are 0 or 1; R3, R4 and R5 are each independently hydrogen or a nitrogen-containing C6-C30 aryl, heteroaryl or biphenyl.

[0041] In some specific embodiments, the chemical structural formula of the blue light dopant is the following chemical structural formula 2-1, chemical structural formula 2-2 and chemical structural formula 2-3:

[0042]

[0043] According to the embodiments of the present disclosure, the blue light dopant satisfies at least one of the following conditions: HOMO energy level is -5.8 to -5.2 eV (for example, HOMO energy level is -5.8 eV, -5.7 eV, -5.6 eV, -5.5 eV, -5.4 eV, -5.3 eV,); LUMO energy level is -2.1 to -3.1 eV (for example, -2.1 eV, -2.3 eV, -2.5 eV, -2.8 eV, -2.9 eV, -3.0 eV, -3.1 eV). As a result, the blue dopant has better performance, which helps to further extend the service life of the blue light OLED device.

[0044] According to the embodiments of the present disclosure, referring to Figure 2 The blue OLED device includes an anode (ITO) 10, a hole injection layer (HIL) 20, a hole transport layer (HTL) 30, the blue light emitting layer 40, an electron injection layer (EIL) 50, an electron transport layer (ETL) 60 and a cathode 70 which are stacked in sequence. There are no special requirements for the materials for forming the hole injection layer (HIL), the hole transport layer (HTL), the electron injection layer (EIL) and the electron transport layer (ETL), and those skilled in the art can flexibly select the materials used in conventional technologies according to actual conditions.

[0045] In another aspect of the present invention, the present invention provides a display panel. According to an embodiment of the present invention, the display panel includes the above-mentioned blue light OLED device. As a result, the blue light OLED device of the display panel has a longer service life, thereby helping to extend the service life of the display panel. Those skilled in the art can understand that the display panel has all the features and advantages of the above-mentioned blue light OLED device, which will not be described in detail here.

[0046] Those skilled in the art will appreciate that the blue light OLED device described above in the display panel also includes the necessary structures and components of a conventional display panel, such as a red light OLED device, a green light OLED device, a TFT substrate, an encapsulation layer for encapsulating the OLED device, a glass cover plate, and other necessary structures and components.

[0047] In some specific embodiments, referring to Figure 3 Based on the same inventive concept, the embodiment of the present disclosure further provides a display panel, such as Figure 3As shown, it includes a plurality of the above-mentioned blue light OLED devices, red light OLED devices, and green light OLED devices provided by the embodiments of the present disclosure. Specifically, the display panel includes: a substrate 01, a thin film transistor 02 located on the substrate 01, an anode 100 connected to the drain of the thin film transistor 02, a pixel defining layer 03 for defining the light-emitting area of ​​each pixel, a spacer 04, a first auxiliary functional layer 400 such as a hole injection layer and a hole transport layer formed in sequence on the pixel defining layer 03, a light-emitting layer 300, a second auxiliary functional layer 500 such as an electron transport layer, a cathode 200, etc., wherein the first auxiliary functional layer 400, the second auxiliary functional layer 500, and the cathode 200 are film layers disposed on the entire surface of the substrate 01, and the light-emitting layer 300 in different pixel light-emitting areas has different materials and thicknesses. Figure 3 Only one feasible structure of the pixel light emitting areas of R, G, and B and a thin film transistor of one pixel is illustrated, and the structure of the display panel is not limited thereto.

[0048] In another aspect of the present invention, the present invention provides a display device. According to an embodiment of the present invention, the display device includes the display panel described above. The display device has a long service life and a high cost performance. Those skilled in the art can understand that the display device has all the features and advantages of the display panel described above, and no further elaboration is given here.

[0049] According to the embodiments of the present invention, there is no special requirement for the specific type of the display device, and those skilled in the art can flexibly select it according to the actual situation. In some embodiments, the specific type of the display device includes but is not limited to mobile phones, televisions, notebooks, iPads, kindles, game consoles and other display devices with display functions.

[0050] Example

[0051] Example 1

[0052] The blue OLED device includes an anode, a hole transport layer HTL, a blue light emitting layer, an electron blocking layer EBL, an electron transport layer ETL and a cathode stacked in sequence. The blue light emitting layer includes a blue light emitting host BH and a blue light dopant BD, wherein:

[0053] The chemical structure of the blue light emitting host BH is the chemical structure 1-1 described above, and its HOMO energy level is -5.92eV, LUMO is -3.01eV, and the hole mobility is 3.2*10 -9 , the electron mobility is 9.6*10 -8The chemical formula of the blue light dopant BD is the chemical formula 2-1 mentioned above, and its HOMO is -5.36eV ​​and LUMO is -2.71eV. Thus, the HOMO energy level difference between BH and BD is 0.56eV. Among them, based on the total mass of the blue light emitting layer, the doping content of BD is 5%.

[0054] Example 2

[0055] The structure of the blue light OLED device is the same as that in Example 1. The difference between this embodiment and Example 1 is that the doping content of BD is 3% based on the total mass of the blue light emitting layer.

[0056] Example 3

[0057] The structure of the blue light OLED device is the same as that in Example 1. The difference between this embodiment and Example 1 is that the doping content of BD is 1% based on the total mass of the blue light emitting layer.

[0058] Example 4

[0059] The blue OLED device includes an anode, a hole transport layer HTL, a blue light emitting layer, an electron blocking layer EBL, an electron transport layer ETL and a cathode stacked in sequence. The blue light emitting layer includes a blue light emitting host BH and a blue light dopant BD, wherein:

[0060] The chemical structure of the blue light emitting host BH is the chemical structure 1-1 described above, and its HOMO energy level is -5.92eV, LUMO is -3.01eV, and the hole mobility is 3.2*10 -9 , the electron mobility is 9.6*10 -8 The chemical formula of the blue light dopant BD is the chemical formula 2-2 described above, and its HOMO is -5.68eV and LUMO is -3.08eV. Thus, the HOMO energy level difference between BH and BD is 0.24eV. ​​Among them, based on the total mass of the blue light emitting layer, the doping content of BD is 5%.

[0061] Example 5

[0062] The structure of the blue light OLED device is the same as that in Example 1. The difference between this embodiment and Example 1 is that the doping content of BD is 3% based on the total mass of the blue light emitting layer.

[0063] Example 6

[0064] The structure of the blue light OLED device is the same as that in Example 1. The difference between this embodiment and Example 1 is that the doping content of BD is 1% based on the total mass of the blue light emitting layer.

[0065] The voltage, luminous efficiency and life of the blue OLED devices in the above embodiments 1-6 were tested. The test results are shown in Table 1 below.

[0066] Table 1

[0067] BD doping ratio Voltage (V) <![CDATA[Luminous efficiency (cd / cm 2 )]]> Lifespan (hours) Example 1 5％ 100 100％ 100％ Example 2 3％ 99 104％ 110％ Example 3 1％ 99 106％ 117％ Example 4 5％ 100 103％ 111％ Example 5 3％ 100 103％ 104％ Example 6 1％ 99 104％ 95％

[0068] It should be noted that the data of luminous efficiency in Table 1 are calculated based on Example 1, that is, the luminous efficiency of the implemented blue OLED device is defined as 100%, and the luminous efficiency of the blue OLED device in Example 2 is 104% compared with Example 1. Similarly, the lifespan data in Table 1 are also based on the blue OLED device in Example 1, and its lifespan is defined as 100%, and the lifespan of the blue OLED device in Example 2 is 110% compared with Example 1.

[0069] By comparing Examples 1-3, it can be seen that when the chemical formula of BH is the chemical formula 1-1 described above, and the chemical formula of BD is the chemical formula 2-1 described above (the energy level difference is 0.56 eV, which is greater than 0.4 eV), as the BD doping ratio decreases, the luminous efficiency and life of the blue light OLED device gradually improve.

[0070] By comparing Examples 4-6, it can be seen that when the chemical formula of BH is the chemical formula 1-1 described above, and the chemical formula of BD is the chemical formula 2-2 described above (the energy level difference is 0.24 eV, less than 0.4 eV), as the BD doping ratio decreases, the luminous efficiency and life of the blue light OLED device gradually decrease.

[0071] It can be seen from the above results that when different materials are selected for BH and BD, as the doping ratio of BD decreases, the life span or luminous efficiency of the device gradually increases or decreases.

[0072] By comparing Example 1 and Example 4, it can be seen that when the BD material is selected as 2-1, the luminous efficiency and life of the blue light OLED device are better than those of the device using the BD material of 2-2.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A blue light OLED device, characterized in that: The invention comprises a blue light emitting layer, wherein the blue light emitting layer comprises a blue light emitting main body and a blue light dopant, wherein the content of the blue light dopant is less than or equal to 6% based on the total mass of the light emitting layer; The chemical structural formula of the blue light emitting main body is ； The chemical structural formula of the blue light dopant is 。 2. The blue light OLED device according to claim 1, characterized in that: The invention comprises an anode, a hole injection layer, a hole transport layer, the blue light emitting layer, an electron injection layer, an electron transport layer and a cathode which are stacked in sequence.

3. A display panel, characterized in that: The invention comprises the blue light OLED device as claimed in claim 1 or 2.

4. A display device, characterized in that: Comprising the display panel as claimed in claim 3.

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