Organic light-emitting diode having green light-emitting layer and device using same

Abstract

An organic light-emitting diode (OLED) device according to an embodiment of the present invention includes a light-emitting layer between a positive electrode and a negative electrode, wherein the light-emitting layer includes a host-dopant structure, and the host may comprise a nucleic acid base material.

Description

Organic light-emitting diode having a green light-emitting layer and device utilizing the same

[0001] The present disclosure relates to an organic light emitting diode (OLED) having a green light emitting layer and a device utilizing the same.

[0002] Organic electroluminescent (EL) devices have been known for a long time, but their performance limitations have hindered their widespread application. The simplest form of an OLED device consists of an anode for hole injection, a cathode for electron injection, and an organic medium inserted between these electrodes to facilitate charge recombination, which leads to luminescence. These devices are called organic light-emitting diodes, or OLEDs.

[0003] More recent organic EL devices may include organic EL elements comprised of very thin layers between an anode and a cathode. Here, the term "organic EL element" refers to layers comprised between the anode and the cathode. Reducing the thickness of the device lowers the resistance of the organic layers, allowing the devices to operate at much lower voltages. One organic layer of the EL element adjacent to the anode is configured to transport holes and is called a hole transport layer, while the other organic layer is configured to transport electrons and is called an electron transport layer. This structure can effectively generate electroluminescence due to the recombination of injected holes and electrons within the organic EL element.

[0004] Three-layer organic EL devices have been proposed, which include an organic emitting layer (EML) between a hole transport layer and an electron transport layer as described above. The emitting layer typically includes a dopant and a host layer. Four-layer EL devices have been proposed, which include a hole injection layer (HIL), a hole transport layer (HTL), an emitting layer (EML), and an electron transport / injection layer (ETL). These structures have shown improved device efficiency.

[0005] However, with the recent increase in interest in implantable devices with biocompatibility and biodegradability, there has been a demand for light-emitting diodes that not only exhibit high luminous efficiency and high color purity while providing lower device voltage and power consumption, but also have performance that is suitable for implantation into the human body using environmentally friendly materials.

[0006] However, while optical sensors and detectors using biocompatible materials are being developed, research in the field of electrically driven light-emitting devices remains lacking. In particular, organic light-emitting diodes (OLEDs) utilize highly biologically toxic active molecules such as benzene and anthracene, necessitating the development of new materials.

[0007] Although OLEDs have been implemented using biocompounds such as chlorophyll a, cytochrome c, myoglobin, and hemin as light-emitting layers, OLEDs utilizing the most advanced host-dopant system have not yet been studied.

[0008] Therefore, in the present disclosure, an OLED that can ultimately be transplanted into a living body is intended to be implemented by configuring a light-emitting layer with a biocompatible nucleic acid base material.

[0009] In this disclosure, an organic light-emitting diode is manufactured using a material with high biocompatibility.

[0010] In this disclosure, an OLED is manufactured by applying a highly biocompatible material to a host dopant structure.

[0011] An organic light emitting diode (OLED) device comprising a green light emitting layer between an anode and a cathode according to one aspect of the present disclosure, wherein the light emitting layer comprises a host-dopant structure, and the host may be composed of a nucleic acid base material.

[0012] In one embodiment, the dopant may be comprised of C545T (coumarin 545T).

[0013] In one embodiment, the nucleic acid base material is composed of uracil, and the light-emitting layer can be formed by co-depositing the nucleic acid base material and the dopant.

[0014] In one embodiment, the nucleic acid base material may be composed of any one of adenine, cytosine, and thymine.

[0015] In one embodiment, the OLED device further includes an electron injection layer, an electron transport layer, a hole transport layer, and a hole injection layer, and the light-emitting layer can be formed by thermal deposition with the electron transport layer and the hole transport layer.

[0016] In one embodiment, the light-emitting layer can be formed by co-depositing the host to a thickness of 28.5 nm and the dopant to a thickness of 1.5 nm.

[0017] In one embodiment, the light-emitting layer can emit green light.

[0018] An electronic device including an organic light emitting diode (OLED) according to another aspect of the present disclosure includes a display unit, a power unit, a transceiver unit, and an organic light emitting diode (OLED) including a light emitting layer between an anode and a cathode, wherein the light emitting layer includes a host-dopant structure, and the host may be composed of a nucleic acid base material.

[0019] According to the present disclosure, an organic light-emitting diode having high biocompatibility and biodegradability can be manufactured by configuring the host of the light-emitting layer with a nucleic acid base material.

[0020] To more fully understand the drawings cited in the detailed description of the present disclosure, a brief description of each drawing is provided.

[0021] FIG. 1 is a drawing showing the structure of an organic light-emitting diode device according to one embodiment of the present disclosure.

[0022] FIGS. 2A to 2D are diagrams showing an energy band structure arrangement using an organic nucleic acid material according to one embodiment of the present disclosure.

[0023] FIGS. 3A to 3D are diagrams showing the electroluminescence characteristics of an OLED produced using a nucleic acid base material according to one embodiment of the present disclosure.

[0024] The technical concept of the present disclosure is susceptible to various modifications and various embodiments. Specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the technical concept of the present disclosure to specific embodiments, and it should be understood that the scope of the present disclosure encompasses all modifications, equivalents, and alternatives.

[0025] When explaining the technical concepts of the present disclosure, detailed descriptions of related known technologies will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, numbers (e.g., "first," "second," etc.) used throughout the description of this specification are merely identifiers used to distinguish one component from another.

[0026] Additionally, in this specification, when a component is referred to as being “connected” or “connected” to another component, it should be understood that the component may be directly connected or connected to the other component, but may also be connected or connected via another component in between, unless there is a specific description to the contrary.

[0027] In addition, terms such as “~part”, “~device”, “~sub-subject”, and “~module” described in this specification mean a unit that processes at least one function or operation, which may be implemented by hardware such as a processor, a microprocessor, a microcontroller, a central processing unit (CPU), a graphics processing unit (GPU), an accelerate processor unit (APU), a drive signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a combination of hardware and software, and may also be implemented in a form combined with a memory that stores data necessary for processing at least one function or operation.

[0028] And it is to be clarified that the division of components in this specification is only a division based on the main function of each component. In other words, two or more components described below may be combined into one component, or one component may be further divided into two or more components with more detailed functions. In addition to its own main function, each component described below may additionally perform some or all of the functions of other components, and of course, some of the main functions of each component may be exclusively performed by other components.

[0029] In describing embodiments of the present disclosure, detailed descriptions of related functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0030] For the same reason, some components in the attached drawings may be exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0031] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments are provided only to ensure that the description of the present disclosure is complete and to fully inform those skilled in the art of the scope of the invention, and the claimed scope of the present disclosure is defined solely by the scope of the claims.

[0032] Hereinafter, various embodiments according to the technical idea of ​​the present disclosure will be described in detail.

[0033]

[0034] FIG. 1 is a drawing showing the structure of an organic light-emitting diode device according to one embodiment of the present disclosure.

[0035] FIG. 1 may illustrate a typical structure of an OLED having various materials described in the present disclosure.

[0036] Referring to FIG. 1, the OLED (100) may include a substrate (180), an anode (170), a hole injection layer (HIL) (160), a hole transport layer (HTL) (150), an emission layer (EML) (140), an electron transport layer (ETL) (130), an electron injection layer (EIL) (120), and a cathode (110). In FIG. 1, the OLED is illustrated as being composed in the following order from the bottom: a substrate (180), an anode (170), a hole-injection layer (160), a hole-transport layer (150), an emission layer (140), an electron-transport layer (130), an electron injection layer (120), and a cathode (110). However, in reality, the positions are not limited thereto, and the substrate may optionally be positioned on the cathode side, or the substrate itself may constitute an anode or a cathode.

[0037] In the OLED (100), the cathode (110) can receive electrons from a voltage / current source (190) through a wire (195) to inject electrons. A metal having a reflectivity higher than a predetermined level can be used for the cathode (110) to send light transmitted to the outside toward the substrate. In addition, a metal having a low work function can be used for the cathode (110) to effectively inject electrons into the electron transport layer (130). For example, aluminum (Al), calcium (Ca), magnesium (Mg), or silver (Ag) can be used for the cathode (110), and an alloy thereof can also be used. The thickness of the cathode can be configured to be approximately 100 nm (nanometers).

[0038] The electron injection layer (120) is a layer that injects electrons injected from the cathode into the interior, and may be composed of an alkali metal compound such as an organic lithium compound, for example. The electron injection layer (120) may be composed in a range of 0.1 nm to 20 nm. For example, in the present disclosure, the electron injection layer is composed of 1 nm of Liq (8-Quinolinolato lithium).

[0039] The electron transport layer (130) may be a layer for transferring electrons injected from the electron injection layer (120) to the light-emitting layer (140). The electron transport layer (130) may be composed of materials such as anthracene derivatives, chelated oxinoid compounds, pyridine, imidazole, oxazole, thiazole, and cyano group polymers. The electron transport layer (130) may be composed in a range of 5 nm to 200 nm. For example, in the present disclosure, an electron transport layer (130) composed of 35 nm of B3PYMPM (4,6-Bis(3,5-di-3-pyridinylphenyl)-2-methylpyrimidine) may be used.

[0040] The anode (170) can perform the role of injecting holes. Unlike the cathode (110), a material with a high work function can be used, and since it is a layer that must transmit light to the outside, the transmittance must be high, so a transparent electrode can be mainly used. Indium tin oxide (ITO), indium-zinc oxide, tin oxide, aluminum zinc oxide, etc. can generally be used as the transparent electrode.

[0041] The hole injection layer (160) may be a layer for minimizing the loss of holes injected into the light-emitting layer (140). That is, the hole injection layer (160) may play a role in promoting hole injection from the anode (170) to the hole transport layer (150), thereby reducing the driving voltage of the OLED. The hole injection layer (160) may mainly use a material such as an aromatic amine, and in the present disclosure, hexaazatriphenylene saline hexacarbonitrile (HAT-CN) was used. The hole injection layer (160) may be configured to have a thickness of 0.1 nm to 200 nm.

[0042] The hole transport layer (150) can perform a mobility control role to transport holes injected from the hole injection layer (160) to the light-emitting layer (140). Aromatic tertiary amines and the like can be mainly used as materials for the hole transport layer (150). In the present disclosure, TAPC (1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane) was used. The hole transport layer (150) can be configured to have a thickness of 5 nm to 200 nm.

[0043] The substrate (180) may be in contact with an anode (170) or a cathode (110). The electrode in contact with the substrate may be defined as a lower electrode. The substrate (180) may be made of a material having different light transmittances depending on the intended emission. For example, transparent glass or plastic may be primarily used as the substrate (180). In the present disclosure, it is assumed that glass is used as the substrate (180), but the present invention is not limited thereto.

[0044] The light-emitting layer (140) may be a layer that emits light when holes and electrons recombine. The light-emitting layer (140) may be composed of a host and a dopant. The host may be used to promote holes to combine with electrons to generate excitons. The dopant receives the generated excitons and emits light. Conventionally, fluorescent materials such as anthracene, Alq3, and PPV, and phosphorescent materials such as Pt(OEP) and Ir(Ppy)3 have been used. However, these materials have biologically harmful properties, making it difficult to use them in implantable OLEDs that are biocompatible or biodegradable.

[0045] To address these issues, the present disclosure proposes a method for constructing a host using a nucleic acid base material. Nucleic acid is a broad concept, referring to polymeric substances present in biological cells, with DNA and RNA being representative examples. Because nucleic acids contain the substances that constitute living organisms, they are highly biocompatible and biodegradable. Nucleic acids are fundamentally composed of nucleotides, and the types of base materials that constitute them include adenine, guanine, cytosine, thymine, and uracil.

[0046] In the light-emitting layer (140) of the present disclosure, a nucleic acid base material is used as a host and C545T (coumarin 545T) is used as a dopant. For example, a light-emitting layer of 30 nm in total can be formed by co-depositing a 28.5 nm nucleic acid base material layer and a 1.5 nm C545T layer. Nucleic acid base materials have excellent carrier transport capabilities and maintain their properties without losing their molecular structure even when forming a thin film through vacuum thermal deposition, so they can be utilized as a host.

[0047] Specific materials that can be utilized as nucleic acid base materials in OLEDs are as follows.

[0048]

[0049] (1) Adenine

[0050] Adenine can be structured as follows:

[0051]

[0052] (2) Taimin

[0053] A thymine can be structured as follows:

[0054]

[0055]

[0056] (3) Cytosine

[0057] Cytosine can be structured as follows:

[0058]

[0059]

[0060] (4) Eurasil

[0061] The uracil can be structured as follows:

[0062]

[0063]

[0064]

[0065] (5) Guanine

[0066] Guanine can be structured as follows:

[0067]

[0068]

[0069] The nucleic acid base materials described above may exist in isomers, and all may be applicable.

[0070]

[0071] FIGS. 2A to 2D are diagrams showing an energy band structure arrangement using an organic nucleic acid material according to one embodiment of the present disclosure.

[0072] Figure 2a shows the energy band structure arrangement when adenine is used as the host. Figure 2b shows the energy band structure arrangement when thymine is used as the host. Figure 2c shows the energy band structure arrangement when cytosine is used as the host. Figure 2d shows the energy band structure arrangement when uracil is used as the host.

[0073] In the OLED structure of FIGS. 2A to 2D, all layers except the light-emitting layer use the same structure. For example, an aluminum layer may be used for the cathode (210), Liq for the electron injection layer (220), B3PYMPM for the electron transport layer (230), ITO for the anode (270), HAT-CN for the hole injection layer (260), and TAPC for the hole transport layer (250).

[0074] To create OLED, ITO patterned to have an active area of ​​3 mm x 3 mm was used as an anode, and sequential washing was performed using acetone, isopropyl alcohol, and distilled water before the organic layer was deposited. Cleaning can be performed through UVO surface treatment.

[0075] The OLEDs of FIGS. 2a to 2d were deposited to have 5 nm of HAT-CN, 40 nm of TAPC, 30 nm of light-emitting layer, 35 nm of B3PYMPM, 1 nm of Liq, and 100 nm of Al, and the doping concentration of the light-emitting layer was 5 wt%, and the deposition speed was 2.0 A / s.

[0076] For efficient energy transfer through the host-dopant system in the OLED's emission layer, there must be overlap between the host material's photoluminescence spectrum and the dopant's absorption spectrum. The absorption spectrum of C545T, used as a dopant, ranges from 400 to 500 nm, while that of the nucleic acid base material ranges from 450 to 550 nm, demonstrating some overlap.

[0077] Additionally, the band gap of the host material must completely encompass the band gap of the dopant. For C545T, used as a dopant, the LUMO is -3.0 eV and the HOMO is -5.6 eV. Therefore, the nucleic acid base material to be utilized as a host must have a band gap greater than -3.0 to -5.6.

[0078] Referring to Fig. 2a, this is a drawing showing the energy band structure arrangement of an OLED (200a) utilizing adenine as a host. Since adenine in the first light-emitting layer (240a) is confirmed to be -2.2 eV to -6.0 eV, it can be confirmed that it completely encompasses the band gap of the dopant.

[0079] Referring to Fig. 2b, this is a drawing showing the energy band structure arrangement of an OLED (200b) utilizing thymine as a host. Since thymine in the second light-emitting layer (240b) is confirmed to be -2.8 eV to -6.5 eV, it can be confirmed that it completely encompasses the band gap of the dopant.

[0080] Referring to Fig. 2c, this is a drawing showing the energy band structure arrangement of an OLED (200c) utilizing cytosine as a host. Since cytosine in the third light-emitting layer (240c) is confirmed to be -2.6 eV to -6.2 eV, it can be confirmed that it completely encompasses the band gap of the dopant.

[0081] Referring to Fig. 2d, this is a drawing showing the energy band structure arrangement of an OLED (200d) utilizing uracil as a host. Since uracil in the fourth light-emitting layer (240d) is confirmed to be -3.0 eV to -6.7 eV, it can be confirmed that it completely encompasses the band gap of the dopant.

[0082]

[0083] FIGS. 3A to 3D are diagrams showing the electroluminescence characteristics of an OLED produced using a nucleic acid base material according to one embodiment of the present disclosure.

[0084] Figure 3a shows the electrical characteristics of an OLED produced using adenine, Figure 3b shows the electrical characteristics of an OLED produced using thymine, Figure 3c shows the electrical characteristics of an OLED produced using cytomine, and Figure 3d shows the electrical characteristics of an OLED produced using uracil.

[0085] Referring to Fig. 3a, for the adenine device, the driving voltage is 4 V and the electroluminescence peak can have a range of 530 to 570 nm.

[0086] Referring to Figure 3b, in the case of the thymine element, the driving voltage is 2.5 V, which is lower than that of the adenine element, but the current density is relatively low, so light is emitted weakly.

[0087] Referring to Figure 3c, it can be seen that the driving voltage of the cytosine element is 8 V, which is higher than that of adenine and thymine, but the current density is also low, indicating that light is emitted very weakly.

[0088] Referring to Figure 3d, for the uracil element, the driving voltage is 5.6 V and the electroluminescence peak has a range of 530 to 570 nm, and it can be seen that light is emitted more strongly than thymine and cytosine.

[0089] Anyone with ordinary skill in the art to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the technical idea of ​​the present disclosure.

[0090] Accordingly, the embodiments illustrated in the present disclosure are not intended to limit the technical idea of ​​the present disclosure but rather to explain it, and the scope of the technical idea of ​​the present disclosure is not limited by these embodiments.

[0091] The scope of protection of the technical idea of ​​the present disclosure should be interpreted by the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the technical virtual scope of the present disclosure.

Claims

1. An organic light-emitting diode (OLED) device comprising a light-emitting layer between an anode and a cathode, The above light-emitting layer comprises a host-dopant structure, The above host is an OLED device composed of a nucleic acid base material.

2. In paragraph 1, The above dopant is an OLED device composed of C545T (coumarin 545T).

3. In paragraph 1, The above nucleic acid base material is composed of uracil, An OLED device in which the above light-emitting layer is formed by co-depositing the above nucleic acid base material and the above dopant.

4. In paragraph 1, An OLED device wherein the above nucleic acid base material is composed of any one of adenine, cytosine, guanine, and thymine.

5. In paragraph 1, The above OLED device: Further comprising an electron injection layer, an electron transport layer, a hole transport layer, and a hole injection layer, An OLED device in which the light-emitting layer is formed by thermal deposition with the electron transport layer and the hole transport layer.

6. In paragraph 1, The above light-emitting layer is an OLED device formed by co-depositing the host at 28.5 nm and the dopant at 1.5 nm.

7. In paragraph 1, The above light-emitting layer is an OLED device that emits green light.

8. In an electronic device including an organic light-emitting diode (OLED), Includes a display unit, a power unit, and a transmitter / receiver unit, An organic light emitting diode (OLED) comprising a light emitting layer between an anode and a cathode, The above light-emitting layer comprises a host-dopant structure, The above host is an electronic device composed of a nucleic acid base material.

9. In paragraph 8, The above nucleic acid base material is composed of uracil, An electronic device in which the above light-emitting layer is formed by co-deposition of the above nucleic acid base material and the above dopant.

10. In paragraph 8, An electronic device wherein the nucleic acid base material is composed of any one of adenine, cytosine, guanine, and thymine.

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