Organic light-emitting device and preparation method thereof

Abstract

The present invention discloses an organic light-emitting device and a method for preparing the same. The organic light-emitting device comprises: a first electrode, a first transmission layer, an organic light-emitting layer and a second electrode; the material used in the first transmission layer comprises a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different. The embodiments of the present invention can improve the light-emitting efficiency and the light-emitting brightness.

Description

Technical Field

[0001] The present invention relates to the field of organic light emitting technology, and in particular to an organic light emitting device and a preparation method thereof. Background Art

[0002] In the actual application of organic light-emitting devices, the brightness needs to be improved in many cases. However, the carrier mobility of organic light-emitting materials is low, which leads to carrier accumulation. The carrier density in the device is low, and the luminous efficiency of the organic light-emitting device is reduced, making it difficult for the device to achieve high brightness. Summary of the invention

[0003] The invention provides an organic light emitting device and a preparation method thereof, so as to improve the light emitting efficiency and the light emitting brightness.

[0004] According to one aspect of the present invention, there is provided an organic light emitting device, comprising:

[0005] A first electrode, a first transmission layer, an organic light-emitting layer, and a second electrode;

[0006] The material used for the first transmission layer includes a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different.

[0007] Optionally, the difference in refractive index between different grains of the first polycrystalline metal oxide is greater than 0.1.

[0008] Optionally, the grain size of the first polycrystalline metal oxide is in the range of 50 nm to 900 nm.

[0009] Optionally, the first polycrystalline metal oxide includes polycrystalline zinc oxide, polycrystalline titanium oxide or polycrystalline molybdenum oxide.

[0010] Optionally, the first electrode is a cathode, the second electrode is an anode, and the first transport layer is an electron transport layer; or,

[0011] The first electrode is an anode, the second electrode is a cathode, the first transport layer is a hole transport layer, the material used by the first transport layer includes a first polycrystalline metal oxide doped with N atoms, and a second transport layer is also included between the second electrode and the organic light-emitting layer, and the material of the second transport layer includes an organic polymer.

[0012] Optionally, the first transmission layer is multiplexed as an anti-short circuit layer.

[0013] Optionally, the material used for the organic light-emitting layer includes a non-doped aggregation-inducing material or an aggregation-inducing TADF material.

[0014] Optionally, a first injection layer is further arranged between the first electrode and the first transmission layer, and the material of the first injection layer includes a second polycrystalline metal oxide, and the crystal plane orientations of the grains of the second polycrystalline metal oxide are different; the second polycrystalline metal oxide includes polycrystalline zinc oxide, polycrystalline titanium oxide or polycrystalline molybdenum oxide.

[0015] According to another aspect of the present invention, there is provided a method for preparing an organic light-emitting device, comprising:

[0016] preparing a first electrode;

[0017] A first transmission layer is prepared on one side of the first electrode; wherein the material used for the first transmission layer includes a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different;

[0018] An organic light-emitting layer is formed on a side of the first transport layer away from the first electrode;

[0019] A second electrode is prepared on a side of the organic light emitting layer away from the first electrode.

[0020] Optionally, a first transport layer is prepared on one side of the first electrode, comprising:

[0021] A first polycrystalline metal oxide solution is prepared by a sol-gel method, and the first polycrystalline metal oxide solution is disposed on one side of the first electrode to form a first transmission layer;

[0022] Alternatively, the first transport layer is formed on one side of the first electrode by using a metal organic compound chemical vapor deposition process.

[0023] In this embodiment, the first transmission layer is made of metal oxide. Since the carrier mobility of metal oxide is relatively high, the current density in the organic light-emitting device can be increased, the luminous efficiency of the device can be increased, and the luminous brightness can be increased. In addition, the first transmission layer is made of first polycrystalline metal oxide, and the crystal plane orientations between the grains of the first polycrystalline metal oxide are different, so that different grains in the first polycrystalline metal oxide have different refractive indices, so that the first transmission layer has a higher light extraction efficiency, and the luminous brightness of the organic light-emitting device is further improved.

[0024] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 It is a schematic diagram of an organic light-emitting device provided by an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of another organic light-emitting device provided by an embodiment of the present invention.

[0028] Figure 3 is a schematic diagram of a light emitting device provided by an embodiment of the present invention.

[0029] Figure 4 It is a flow chart of a method for preparing an organic light-emitting device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] An embodiment of the present invention provides an organic light emitting device, Figure 1 is a schematic diagram of an organic light-emitting device provided by an embodiment of the present invention, with reference to Figure 1 , the organic light emitting device comprises:

[0033] A first electrode 10, a first transmission layer 20, an organic light emitting layer 30 and a second electrode 40;

[0034] The material used for the first transmission layer 20 includes a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different.

[0035] Among them, the first electrode 10 is a light-transmitting electrode, and the second electrode 40 is a reflective electrode. The first electrode 10 is an anode, and the second electrode 40 is a cathode, or the first electrode 10 is a cathode, and the second electrode 40 is an anode. The first polycrystalline metal oxide is a metal oxide with a variety of grain sizes. The metal oxide can be zinc oxide or titanium oxide. Electrons (holes) are transmitted to the organic light-emitting layer 30 via the first electrode 10 and the first transport layer 20, and holes (electrons) are transmitted to the organic light-emitting layer 30 via the second electrode 40. Holes and electrons recombine in the organic light-emitting layer 30 to generate excitons, and the excitons de-excite to emit light. In the existing organic light-emitting structure, the carrier mobility of the first transport layer 20 is low, resulting in low luminous efficiency of the organic light-emitting device.

[0036] In this embodiment, the first transmission layer 20 is made of metal oxide. Since the carrier mobility of metal oxide is relatively high, the current density in the organic light-emitting device can be increased, the luminous efficiency of the device can be increased, and the luminous brightness can be increased. In addition, the first transmission layer 20 is made of a first polycrystalline metal oxide, and the crystal plane orientations between the grains of the first polycrystalline metal oxide are different, so that different grains in the first polycrystalline metal oxide have different refractive indices, so that the first transmission layer 20 has a higher light extraction efficiency, and the luminous brightness of the organic light-emitting device is further improved.

[0037] Based on the above embodiment, optionally, the difference in refractive index between different grains of the first polycrystalline metal oxide is greater than 0.1.

[0038] Specifically, the difference in refractive index between the grains affects the light extraction efficiency of the first transmission layer 20. The greater the difference in refractive index between the grains, the higher the light extraction efficiency of the first polycrystalline metal oxide. By setting the difference in refractive index between different grains of the first polycrystalline metal oxide to be greater than 0.1, the first transmission layer 20 is ensured to have a higher light extraction efficiency, further improving the luminous brightness of the organic light-emitting device.

[0039] Based on the above embodiment, optionally, the size of the grains of the first polycrystalline metal oxide is in the range of 50 nm to 900 nm.

[0040] Specifically, the grain size affects the wavelength of light that the first polycrystalline metal oxide can transmit. By setting the grain size of the first polycrystalline metal oxide to range from 50nm to 900nm, the first transmission layer 20 has a higher extraction efficiency for light emitted by the organic light-emitting layer 30 .

[0041] Based on the above embodiment, optionally, the first polycrystalline metal oxide includes polycrystalline zinc oxide, polycrystalline titanium oxide or polycrystalline molybdenum oxide.

[0042] Specifically, polycrystalline zinc oxide, polycrystalline titanium oxide and polycrystalline molybdenum oxide all have high electron mobility and a relatively simple preparation process. By setting the first polycrystalline metal oxide to include polycrystalline zinc oxide, polycrystalline titanium oxide or polycrystalline molybdenum oxide, the carrier mobility of the first transport layer 20 is ensured to be high, and the luminous efficiency of the organic light-emitting device is improved while the process difficulty and process cost can be reduced.

[0043] Based on the above embodiments, continue to refer to Figure 1 The first electrode 10 is a cathode, the second electrode 40 is an anode, and the first transport layer 20 is an electron transport layer; or, the first electrode 10 is an anode, the second electrode 40 is a cathode, the first transport layer 20 is a hole transport layer, the first transport layer 20 includes a first polycrystalline metal oxide and a P-type material, and a second transport layer 50 is also included between the second electrode 40 and the organic light-emitting layer 30, and the material of the second transport layer 50 includes an organic polymer.

[0044] Specifically, when the first electrode 10 is a cathode, the second electrode 40 is an anode, and the first transport layer 20 is an electron transport layer, the first transport layer 20 can improve electron mobility so that the electron mobility matches the hole mobility, thereby improving the luminous efficiency of the organic light-emitting device.

[0045] When the first electrode 10 is an anode, the second electrode 40 is a cathode, and the first transport layer 20 is a hole transport layer, the first transport layer 20 includes a first polycrystalline metal oxide doped with N atoms. By doping the polycrystalline metal oxide with N atoms to make the first polycrystalline metal oxide a P-type material, which is used as a hole transport layer, the hole mobility of the hole transport layer can be improved. At the same time, the second transport layer, that is, the electron transport layer, is provided with an organic polymer, so that the electron transport layer has a higher electron mobility, the organic light-emitting device has a higher electron and hole mobility, and the luminous efficiency of the organic light-emitting device is improved. Exemplarily, the organic polymer can be Pedot:pss.

[0046] On the basis of the above embodiment, optionally, the first transmission layer 20 is multiplexed as an anti-short circuit layer.

[0047] Specifically, the thickness of the first transmission layer 20 can be adjusted so that the first transmission layer 20 can cover the dust particles on the substrate 10 to prevent the dust particles from causing a short circuit in the organic light-emitting device. In addition, the thickness of the first transmission layer 20 can be adjusted to adjust the resistance of the first transmission layer 20 to ensure that the current loss of the organic light-emitting device is small when the organic light-emitting device is short-circuited.

[0048] The resistance of the anti-short-circuit layer must reach a certain level so that the short-circuit current after short-circuiting does not exceed 10% of the overall current of the organic light-emitting device, ensuring the normal operation of other light-emitting areas of the organic light-emitting device. The specific thickness of the anti-short-circuit layer can be calculated by the following formula:

[0049]

[0050] Where, ρ: resistivity of the short-circuit protection layer, A 总 : Total area of ​​organic light-emitting devices, A 短 : short-circuit point area, V: normal working voltage; V 增 : acceptable voltage rise, T: thickness of the anti-short circuit layer, J: normal operating current density of the organic light-emitting device, f: ratio of acceptable short circuit current to normal current. The thickness of the first transport layer 20 can be adjusted so that the first transport layer 20 satisfies the above formula, that is, meets the performance requirements of the anti-short circuit resistance. Through calculation, when the thickness of the first transport layer 20 is between 1-200nm, the first transport layer 20 better meets the performance requirements of the anti-short circuit layer.

[0051] Based on the above embodiment, optionally, the material used for the organic light-emitting layer 30 includes a non-doped aggregation-inducing material or an aggregation-inducing TADF material.

[0052] Specifically, the organic light-emitting layer 30 selects non-doped aggregation-inducing materials or aggregation-inducing TADF materials to ensure that the organic light-emitting layer 30 has a high exciton state density, and that the organic light-emitting layer 30 can form and accommodate enough excitons while increasing the current density in the device without causing obvious quenching, thereby improving the efficiency of the device at high brightness.

[0053] Figure 2 is a schematic diagram of another organic light-emitting device provided in an embodiment of the present invention, optionally, refer to Figure 2 A first injection layer 60 is further disposed between the first electrode 10 and the first transmission layer 20 . The material of the first injection layer 60 includes a second polycrystalline metal oxide, and the crystal plane orientations of the grains of the second polycrystalline metal oxide are different.

[0054] The second polycrystalline metal oxide may include polycrystalline zinc oxide, polycrystalline molybdenum oxide or polycrystalline titanium oxide, and the second polycrystalline metal oxide and the first polycrystalline metal oxide may be the same or different.

[0055] By setting the material of the first injection layer 60 to include the second polycrystalline metal oxide, the first injection layer 60 has a higher carrier mobility, further improving the luminous efficiency of the organic light-emitting device. In addition, the first injection layer 60 uses the second polycrystalline metal oxide, and the crystal plane orientations between the grains of the second polycrystalline metal oxide are different, so that different grains in the second polycrystalline metal oxide have different refractive indices, so that the first injection layer 60 has a higher light extraction efficiency, further improving the luminous brightness of the organic light-emitting device.

[0056] Figure 3 is a schematic diagram of a light emitting device provided by an embodiment of the present invention. The embodiment of the present invention also provides a light emitting device, referring to Figure 3 , the light emitting device comprises:

[0057] A substrate 100 and a plurality of organic light-emitting devices 200 according to any embodiment of the present invention disposed on the substrate 100 .

[0058] The light-emitting device provided in the embodiment of the present invention and the organic light-emitting device 200 described in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the organic light-emitting structure described in any embodiment of the present invention.

[0059] The present invention also provides a method for preparing an organic light-emitting device. Figure 4 is a flow chart of a method for preparing an organic light-emitting device provided by an embodiment of the present invention, with reference to Figure 4 , the method for preparing an organic light-emitting device comprises:

[0060] S110, preparing a first electrode.

[0061] Specifically, the first electrode can be prepared on the substrate by a process such as sputtering or coating.

[0062] S120, preparing a first transmission layer on one side of the first electrode; wherein the material used for the first transmission layer includes a first polycrystalline metal oxide, and the crystal plane orientations of the grains of the first polycrystalline metal oxide are different.

[0063] Specifically, the first polycrystalline metal oxide solution can be prepared by a solution method, and then the first transport layer film can be prepared on the first electrode by spin coating or inkjet printing. The first polycrystalline metal oxide can also be prepared on the first electrode by sputtering, that is, the first transport layer is prepared.

[0064] S130, preparing an organic light-emitting layer on a side of the first transmission layer away from the first electrode.

[0065] The organic light-emitting layer can be prepared by an evaporation process. Before preparing the organic light-emitting layer, a first blocking layer can be prepared. After preparing the organic light-emitting layer, a second blocking layer, a second transport layer and a second injection layer can also be prepared. When the first electrode is an anode, the first blocking layer is an electron blocking layer, the second blocking layer is a hole blocking layer, the second transport layer is an electron transport layer, and the second injection layer is an electron injection layer. When the first electrode is a cathode, the first blocking layer is a hole blocking layer, the second blocking layer is an electron blocking layer, the second transport layer is a hole transport layer, and the second injection layer is a hole injection layer.

[0066] S140, preparing a second electrode on a side of the organic light-emitting layer away from the first electrode.

[0067] Specifically, the second electrode may be prepared by using an evaporation process.

[0068] In this embodiment, the first transmission layer is made of metal oxide. Since the carrier mobility of metal oxide is relatively high, the current density in the organic light-emitting device can be increased, the luminous efficiency of the device can be increased, and the luminous brightness can be increased. In addition, the first transmission layer is made of first polycrystalline metal oxide, and the crystal plane orientations between the grains of the first polycrystalline metal oxide are different, so that different grains in the first polycrystalline metal oxide have different refractive indices, so that the first transmission layer has a higher light extraction efficiency, and the luminous brightness of the organic light-emitting device is further improved.

[0069] Based on the above embodiment, optionally, S120, preparing a first transmission layer on one side of the first electrode, includes:

[0070] A first polycrystalline metal oxide solution is prepared by a sol-gel method, and the first polycrystalline metal oxide solution is disposed on one side of the first electrode to form a first transmission layer;

[0071] Alternatively, the first transport layer is formed on one side of the first electrode by using a metal organic compound chemical vapor deposition process.

[0072] Specifically, when the first polycrystalline metal oxide solution is prepared by the sol-gel method, the size of the grains can be controlled by adjusting the annealing temperature, and the crystal plane orientation deviation between the grains can be adjusted by adjusting the precursor concentration ratio in the solution.

[0073] When the first transport layer is prepared by a metal-organic chemical vapor deposition (MOCVD) process, the grain size and the crystal orientation deviation can be controlled by adjusting the substrate temperature and the oxygen partial pressure.

[0074] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0075] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An organic light-emitting device, characterized in that: include: A first electrode, a first transmission layer, an organic light-emitting layer, and a second electrode; The material used for the first transmission layer includes a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different.

2. The organic light emitting device according to claim 1, characterized in that: The difference in refractive index between different grains of the first polycrystalline metal oxide is greater than 0.

1.

3. The organic light emitting device according to claim 1, characterized in that: The grain size of the first polycrystalline metal oxide is in the range of 50 nm to 900 nm.

4. The organic light-emitting device according to any one of claims 1 to 3, characterized in that: The first polycrystalline metal oxide includes polycrystalline zinc oxide, polycrystalline titanium oxide, or polycrystalline molybdenum oxide.

5. The organic light-emitting device according to any one of claims 1 to 3, characterized in that: The first electrode is a cathode, the second electrode is an anode, and the first transport layer is an electron transport layer; or, The first electrode is an anode, the second electrode is a cathode, the first transport layer is a hole transport layer, the material used by the first transport layer includes a first polycrystalline metal oxide doped with N atoms, and a second transport layer is also included between the second electrode and the organic light-emitting layer, and the material of the second transport layer includes an organic polymer.

6. The organic light emitting device according to any one of claims 1 to 3, characterized in that: The first transmission layer is multiplexed as an anti-short circuit layer.

7. The organic light-emitting device according to any one of claims 1 to 3, characterized in that: The material used for the organic light-emitting layer includes a non-doped aggregation-inducing material or an aggregation-inducing TADF material.

8. The organic light emitting device according to any one of claims 1 to 3, characterized in that: A first injection layer is also arranged between the first electrode and the first transmission layer. The material of the first injection layer includes a second polycrystalline metal oxide, and the crystal plane orientations of the grains of the second polycrystalline metal oxide are different; the second polycrystalline metal oxide includes polycrystalline zinc oxide, polycrystalline titanium oxide or polycrystalline molybdenum oxide.

9. A method for preparing an organic light-emitting device, characterized in that: include: preparing a first electrode; A first transmission layer is prepared on one side of the first electrode; wherein the material used for the first transmission layer includes a first polycrystalline metal oxide, and the crystal plane orientations of the crystal grains of the first polycrystalline metal oxide are different; An organic light-emitting layer is formed on a side of the first transport layer away from the first electrode; A second electrode is prepared on a side of the organic light emitting layer away from the first electrode.

10. The method according to claim 9, characterized in that A first transport layer is prepared on one side of the first electrode, comprising: A first polycrystalline metal oxide solution is prepared by a sol-gel method, and the first polycrystalline metal oxide solution is disposed on one side of the first electrode to form a first transmission layer; Alternatively, the first transport layer is formed on one side of the first electrode by using a metal organic compound chemical vapor deposition process.

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