Organic light emitting device and display device

Abstract

The present application provides an organic light-emitting device and a display device, which solves the problem of color deviation of organic light-emitting devices under high temperature conditions in the prior art. The organic light-emitting device includes a cathode, at least one functional layer and a light-emitting layer stacked in sequence; at least one functional layer includes a reversible thermotropic phase change material.

Description

Technical Field

[0001] The present application relates to the technical field of light-emitting devices, and in particular to an organic light-emitting device and a display apparatus. Background Art

[0002] In recent years, organic light-emitting display screens have gradually replaced liquid crystal displays as the mainstream product in the display field. Studies have found that as the temperature rises, organic light-emitting display screens will experience color shift, resulting in poor display effects. Summary of the invention

[0003] In view of this, the embodiments of the present application provide an organic light-emitting device and a display device to solve the problem of color shift of the organic light-emitting device under high temperature conditions in the prior art.

[0004] In the first aspect of the present application, an organic light-emitting device is provided, comprising: a cathode, at least one functional layer and a light-emitting layer stacked in sequence; at least one functional layer comprises a reversible thermotropic phase change material. By setting a reversible thermotropic phase change material, based on the variability of the properties of the reversible thermotropic phase change material, including an increase in energy level at high temperature, a decrease in energy level at high temperature, and complexation with adjacent metal materials at high temperature, the probability of electron injection under high temperature conditions can be reduced by using the reversible thermotropic phase change material, so that the change trend of the device's electronic characteristics under high temperature conditions is consistent with the change trend of the hole characteristics, thereby ensuring that the carrier balance relationship under high temperature and normal temperature conditions is consistent, thereby avoiding a significant decrease in the high temperature life of the device, resulting in a white screen color shift phenomenon after the high temperature life test of the product.

[0005] In one embodiment, at least one functional layer includes a target functional layer, the target functional layer includes a doping material, the doping material is a reversible thermotropic phase change material, and the energy level of the reversible thermotropic phase change material is inversely proportional to the temperature. In this way, as the temperature increases, the electron injection capacity of the reversible thermotropic phase change material decreases, and the electron injection capacity of the main material increases, and the two offset each other, ensuring that the electron injection capacity of the target functional layer is consistent with the normal temperature condition, thereby avoiding the color deviation problem.

[0006] In one embodiment, the target functional layer further includes a main material; at 35°C, the absolute value of the energy level difference between the main material and the doping material is less than 0.03 eV. That is, at room temperature, the energy levels of the doping material and the main material tend to be consistent. In this way, the doping material can be prevented from affecting the electron injection ability of the target functional layer at room temperature.

[0007] In one embodiment, the target functional layer further includes a main material; at 85° C., the absolute value of the energy level difference between the main material and the doping material is greater than 0.1 eV. In this way, for the electron injection capability of the target functional layer, it can be ensured that the negative effect of the reversible thermotropic phase change material is equivalent to the positive effect of the main material.

[0008] In one embodiment, the target functional layer includes any one of an electron transport layer and an electron injection layer.

[0009] In one embodiment, at least one functional layer includes a phase change material layer, and the phase change material layer is composed of a reversible thermally induced phase change material; at 35 °C, the energy levels of the overall formed by the phase change material layer and the two adjacent film layers are distributed stepwise in the film layer arrangement direction, and the energy level of the reversible thermally induced phase change material is proportional to the temperature. In this case, as the temperature increases, the phase change material layer gradually breaks the stepwise distribution law of the energy levels between adjacent film layers, thereby having a negative effect on the electron injection ability, and this negative effect cancels out the positive effect of the adjacent film layer, ensuring that the electron injection ability of the organic light-emitting device is consistent with that at normal temperature, thereby avoiding the problem of color shift.

[0010] In one embodiment, at least one functional layer further includes an electron injection layer, and the electron injection layer and the phase change material layer are stacked; the reversible thermally induced phase change material includes Schiff base materials, and the electron injection layer includes metal materials. In this way, at high temperature, the electron injection layer and the phase change material layer can undergo keto-enol tautomerism and complex with the metal. After complexation, the electron injection work function of the electron injection layer decreases, thereby further ensuring that the electron injection ability of the organic light-emitting device is consistent with that at normal temperature.

[0011] In one embodiment, the energy level relationship between the phase change material layer and any one of the two adjacent film layers satisfies: at 35 °C, 丨LUMO phc -LUMO nb 丨 < 0.03 eV. In this way, it can be ensured that when the temperature rises a little, the phase change material layer can play a role, that is, the sensitivity of the phase change material layer is improved. And / or, at 85 °C, 丨LUMO phc -LUMO nb 丨 > 0.1 eV; where LUMO phc represents the energy level of the phase change material layer, and LUMO nb represents the energy level of any adjacent film layer. In this way, for the electron injection ability, it can be ensured that the negative effect of the phase change material layer is equivalent to the positive effect of any adjacent film layer.

[0012] In one embodiment, the reversible thermally induced phase change material includes any one of spiro compounds, bisanthrone organic compounds, and metal complexes.

[0013] The second aspect of the present application provides a display device, including the organic light-emitting device provided in any of the above embodiments.

[0014] According to the organic light-emitting device and display device provided by the present application, a reversible thermotropic phase change material is arranged in at least one functional layer between the cathode and the anode of the organic light-emitting device. The reversible thermotropic phase change material refers to a material whose material properties change with the change of temperature, and when it returns to the initial temperature, the material properties return to the initial state. The material properties mentioned here include energy level, molecular structure, etc. By setting a reversible thermotropic phase change material, based on the variability of the properties of the reversible thermotropic phase change material, including energy level increase at high temperature, energy level decrease at high temperature, complexation with adjacent metal materials at high temperature, etc., the reversible thermotropic phase change material can be used to reduce the injection probability of electrons under high temperature conditions, so that the change trend of the electronic characteristics of the device under high temperature conditions is consistent with the change trend of the hole characteristics, thereby ensuring that the carrier balance relationship under high temperature and normal temperature conditions is consistent, thereby avoiding a significant decrease in the high temperature life of the device, resulting in a white screen color shift phenomenon after the high temperature life test of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of an organic light-emitting device provided in one embodiment of the present application.

[0016] Figure 2 A schematic structural diagram of an organic light-emitting device provided in the second embodiment of the present application.

[0017] Figure 3 A schematic structural diagram of an organic light-emitting device provided in the third embodiment of the present application.

[0018] Figure 4a Under normal temperature conditions provided in one embodiment of the present application Figure 2 Schematic diagram of the energy level relationship of each film layer in the organic light-emitting device shown.

[0019] Figure 4b Under high temperature conditions provided by an embodiment of the present application Figure 3 Schematic diagram of the energy level relationship of each film layer in the organic light-emitting device shown.

[0020] Figure 5 A schematic structural diagram of an organic light-emitting device provided in the fourth embodiment of the present application. DETAILED DESCRIPTION

[0021] As described in the background technology, organic light-emitting display screens may have color deviation problems in high temperature environments. The inventors have found that one of the reasons for the color deviation problem is that, compared with normal temperature conditions, the electron injection capacity of light-emitting units, such as light-emitting diodes, is significantly improved under high temperature conditions, while the hole injection capacity changes relatively slowly, resulting in changes in the carrier balance relationship, causing changes in luminous efficiency and electrical properties, resulting in color deviation problems.

[0022] In view of this, the embodiments of the present application provide an organic light-emitting device and a display device, in which a reversible thermotropic phase change material is arranged in at least one functional layer between the cathode and the anode of the organic light-emitting device. The reversible thermotropic phase change material refers to a material whose material properties change with the change of temperature, and when it returns to the initial temperature, the material properties return to the initial state. The material properties mentioned here include energy level, molecular structure, etc. By setting a reversible thermotropic phase change material, based on the variability of the properties of the reversible thermotropic phase change material, including energy level increase at high temperature, energy level decrease at high temperature, complexation with adjacent metal materials at high temperature, etc., the reversible thermotropic phase change material can be used to reduce the injection probability of electrons under high temperature conditions, so that the change trend of the electronic characteristics of the device under high temperature conditions is consistent with the change trend of the hole characteristics, thereby ensuring that the carrier balance relationship under high temperature and normal temperature conditions is consistent, thereby avoiding a significant decrease in the high temperature life of the device, resulting in a white screen color shift phenomenon after the high temperature life test of the product.

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] Figure 1 This is a schematic diagram of the structure of an organic light-emitting device provided in one embodiment of the present application. Figure 1 As shown, the organic light-emitting device 10 includes a cathode 11, at least one functional layer and a light-emitting layer 12 stacked in sequence. At least one functional layer includes a target functional layer 13, and the target functional layer 13 can be, for example, an electron transport layer, an electron injection layer, a hole blocking layer, etc. Among them, the electron injection layer is used to inject electrons into the organic light-emitting device. The electron transport layer is used to transfer the electrons injected into the organic light-emitting device to the light-emitting layer 12. The hole blocking layer is used to prevent holes from moving toward the cathode 11.

[0025] The target functional layer 13 includes a main material and a doping material 130. The doping material 130 is a reversible thermotropic phase change material. The energy level of the reversible thermotropic phase change material is inversely proportional to the temperature. In this way, as the temperature rises, the electron injection capacity of the reversible thermotropic phase change material decreases, and the electron injection capacity of the main material increases. The two offset each other, ensuring that the electron injection capacity of the target functional layer 13 is consistent with the normal temperature condition, thereby avoiding the color deviation problem.

[0026] In one example, the reversible thermotropic phase change material is any one of a spirocyclic organic compound, a dianthrone organic compound, and a metal complex.

[0027] In one embodiment, the volume ratio of the doping material 130 in the target functional layer 13 is 3% to 50%.

[0028] In one embodiment, at 35°C, the energy level relationship between the doping material 130 and the host material satisfies: |LUMO dopant -LUMO ETL | < 0.03 eV, where LUMO dopant represents the energy level of the doping material 130, and LUMO ETL represents the energy level of the host material. That is, at room temperature, the energy levels of the doping material 130 and the host material tend to be consistent. In this way, the influence of the doping material 130 on the electron injection ability of the target functional layer 13 can be avoided at room temperature.

[0029] In one embodiment, at 85°C, the energy level relationship between the doping material 130 and the host material satisfies: |LUMO dopant -LUMO ETL | > 0.1 eV, and as the temperature increases, the absolute value of the energy level difference between the doping material 130 and the host material shows a gentle upward trend. In this way, for the electron injection ability of the target functional layer 13, it can be ensured that the negative effect of the reversible thermally induced phase change material is equivalent to the positive effect of the host material.

[0030] In one embodiment, as Figure 1 shown, the organic light-emitting device further includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer stacked in sequence on the side of the light-emitting layer 12 away from the cathode 11, and an anode. Among them, the anode is used to inject holes, the hole injection layer is used to inject holes from the anode into the organic light-emitting device, the hole transport layer is used to transport the holes injected into the organic light-emitting device to the light-emitting layer, and the electron blocking layer is used to prevent electrons from moving towards the anode.

[0031] Figure 2 This is a schematic structural diagram of the organic light-emitting device provided in the second embodiment of the present application. As Figure 2 shown, the organic light-emitting device 20 includes a cathode 11, an electron injection layer 21, an electron transport layer 22, and a light-emitting layer 12 stacked in sequence. In this embodiment, the electron injection layer 21 and the electron transport layer 22 respectively include a host material and a doping material. The doping material is a reversible thermally induced phase change material, and the energy level of the reversible thermally induced phase change material is inversely proportional to the temperature. For the specific technical details of the reversible thermally induced phase change material, reference can be made to Figure 1 the embodiment shown, which will not be elaborated here.

[0032] In other embodiments, a reversible thermotropic phase change material may be provided in the electron injection layer 21 alone. In this case, the electron injection layer 21 includes a main material and a doping material, the doping material is a reversible thermotropic phase change material, and the energy level of the reversible thermotropic phase change material is inversely proportional to the temperature. Alternatively, a reversible thermotropic phase change material may be provided in the electron transport layer 22 alone. In this case, the electron transport layer 22 includes a main material and a doping material, the doping material is a reversible thermotropic phase change material, and the energy level of the reversible thermotropic phase change material is inversely proportional to the temperature.

[0033] Figure 3 This is a schematic diagram of the structure of an organic light-emitting device provided in the third embodiment of the present application. Figure 3 As shown, the organic light emitting device 30 includes a cathode 11, at least one functional layer and a light emitting layer 12 stacked in sequence. At least one functional layer includes a phase change material layer 33, and the phase change material layer 33 is composed of a reversible thermotropic phase change material. That is, in this embodiment, the reversible thermotropic phase change material constitutes a single functional layer. In this way, compared with Figure 1 and Figure 2 As shown, using the reversible thermotropic phase change material as a doping material can reduce the interaction between the reversible thermotropic phase change material and the main material, thereby avoiding affecting the transmission characteristics of the main material, that is, the electron mobility.

[0034] In this embodiment, if Figure 3 As shown, under the condition of 35° C., the energy level of the whole composed of the phase change material layer 33 and the two adjacent film layers is distributed in a step-like manner in the film layer arrangement direction, and the energy level of the reversible thermotropic phase change material is proportional to the temperature.

[0035] For example, Figure 4a Under normal temperature conditions provided in one embodiment of the present application Figure 2 Schematic diagram of the energy level relationship of each film layer in the organic light-emitting device shown. Figure 4b Under high temperature conditions provided by an embodiment of the present application Figure 3 Schematic diagram of the energy level relationship of each film layer in the organic light-emitting device shown. Figure 4a , and the two film layers adjacent to the phase change material layer 33 are the electron injection layer 34 and the electron transport layer 35. Under the condition of 35°C, the energy level of the whole composed of the phase change material layer 33 and the two adjacent film layers is distributed in a step-like manner in the film layer arrangement direction, including three situations: first, the energy levels of the electron injection layer 34, the phase change material layer 33 and the electron transport layer 35 decrease in sequence; second, the energy levels of the electron injection layer 34 and the phase change material layer 33 are equivalent and less than the energy level of the electron transport layer 35, such as Figure 4a As shown; Third, the energy levels of the phase change material layer 33 and the electron transport layer 35 are equivalent and greater than the energy level of the electron injection layer 34. When the temperature rises, as Figure 4bAs shown, for example, at 85°C, the energy level of the phase change material layer 33 rises to be lower than that of the electron injection layer 34. In this case, the phase change material layer 33 breaks the stepped distribution rule of the energy levels between adjacent film layers, which will have a negative effect on the electron injection ability. This negative effect cancels out the positive effect of the electron injection layer 34 and the electron transport layer 35, ensuring that the electron injection ability of the organic light-emitting device 30 is consistent with that at room temperature, thus avoiding the problem of color shift.

[0036] In one embodiment, the energy level relationship between the phase change material layer and any one of the two adjacent film layers satisfies: at 35°C, |LUMO phc -LUMO nb | < 0.03 eV, where LUMO phc represents the energy level of the phase change material layer, and LUMO nb represents the energy level of any adjacent film layer. For example, as Figure 4a shown, the energy levels of the electron injection layer 34 and the phase change material layer 33 satisfy this condition. In this way, it can be ensured that when the temperature rises a little, the phase change material layer 33 can play a role, that is, the sensitivity of the phase change material layer 33 is improved.

[0037] In one embodiment, the energy level relationship between the phase change material layer 33 and any one of the two adjacent film layers satisfies: at 85°C, |LUMO phc -LUMO nb | > 0.1 eV, where LUMO phc represents the energy level of the phase change material layer 33, and LUMO nb represents the energy level of any adjacent film layer. As the temperature rises, the absolute value of the energy level difference between the phase change material layer 33 and any one of the two adjacent film layers shows a gentle upward trend. For example, as Figure 4b shown, the energy levels of the electron injection layer 34 and the phase change material layer 33 satisfy this condition. In this way, for the electron injection ability, it can be ensured that the negative effect of the phase change material layer 33 is equivalent to the positive effect of the electron injection layer 34.

[0038] In one embodiment, the electron injection layer 34 includes a metal material, and the reversible thermally induced phase change material includes a Schiff base material. In this way, at high temperature, the electron injection layer 34 and the phase change material layer 33 can undergo keto-enol tautomerism and complex with the metal. After complexation, the electron injection work function of the electron injection layer 34 decreases, further ensuring that the electron injection ability of the organic light-emitting device 30 is consistent with that at room temperature.

[0039] Figure 5 This is a schematic structural diagram of the organic light-emitting device provided by the fourth embodiment of the present application. As Figure 5As shown, the organic light-emitting device 40 includes a cathode 11, a first phase change material layer 41, an electron injection layer 42, a second phase change material layer 43, an electron transport layer 44, a third phase change material layer 45 and a light-emitting layer 12 stacked in sequence. The first phase change material layer 41, the second phase change material layer 43 and the third phase change material layer 45 are all composed of reversible phase change materials, and the reversible phase change materials in the first phase change material layer 41, the second phase change material layer 43 and the third phase change material layer 45 are the same or different. The specific technical details of the reversible thermotropic phase change material can be referred to. Figure 1 The illustrated embodiments are not described in detail here.

[0040] In other embodiments, any one or any two of the first phase-change material layer 41 , the second phase-change material layer 43 and the third phase-change material layer 45 may be selectively provided.

[0041] The present application also provides a display device, comprising the organic light-emitting device provided by any of the above embodiments.

[0042] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. An organic light-emitting device, characterized in that: include: A cathode, at least one functional layer and a light-emitting layer are stacked in sequence; at least one of the functional layers comprises a reversible thermotropic phase change material; The at least one functional layer includes a target functional layer, the target functional layer includes a doping material, the doping material is the reversible thermotropic phase change material, and the energy level of the reversible thermotropic phase change material is inversely proportional to the temperature; or The at least one functional layer includes a phase change material layer, and the phase change material layer is composed of the reversible thermotropic phase change material. Under the condition of 35°C, the overall energy level of the phase change material layer and the two adjacent film layers is distributed in a stepped manner in the arrangement direction of the film layers, and the energy level of the reversible thermotropic phase change material is proportional to the temperature.

2. The organic light-emitting device according to claim 1, characterized in that: The target functional layer also includes a main material; under the condition of 35° C., the absolute value of the energy level difference between the main material and the doping material is less than 0.03 eV.

3. The organic light-emitting device according to claim 1, characterized in that: The target functional layer also includes a main material; under the condition of 85° C., the absolute value of the energy level difference between the main material and the doping material is greater than 0.1 eV.

4. The organic light-emitting device according to any one of claims 1 to 3, characterized in that: The target functional layer includes any one of an electron transport layer and an electron injection layer.

5. The organic light-emitting device according to claim 1, characterized in that: The at least one functional layer further includes an electron injection layer, and the electron injection layer and the phase change material layer are stacked; the reversible thermotropic phase change material of the phase change material layer includes a Schiff base material, and the electron injection layer includes a metal material.

6. The organic light-emitting device according to claim 1, characterized in that: The energy level relationship between the phase change material layer and any one of the two adjacent film layers satisfies: at 35 °C, 丨LUMO phc -LUMO nb 丨 < 0.03 eV; and / or At 85 °C, |LUMO phc - LUMO nb | > 0.1 eV; Among them, LUMO phc Represents the energy level of the phase change material layer, LUMO nb Represents the energy level of any adjacent film layer.

7. The organic light-emitting device according to claim 1, characterized in that: The reversible thermotropic phase change material of the target functional layer includes any one of spirocyclic organic compounds, dianthrone organic compounds, and metal complexes.

8. A display device, characterized in that: An organic light-emitting device comprising any one of claims 1 to 7.

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