CN103383990A - Application of Hexaazatriphenylene Derivatives in Organic Light-Emitting Devices - Google Patents

Abstract

An application of hexaazatriphenylene derivative in organic light-emitting element. The organic light-emitting element comprises a substrate, an anode, a cathode and at least one electroluminescent structure. The substrate is made of light-permeable material; the anode is electrically connected with a positive electrode of an external electric field and is suitable for providing hole current; the cathode is electrically connected with a negative electrode of an external electric field and is suitable for providing electron current. The electroluminescent structure is arranged between the anode and the cathode; forming at least one hexaazatriphenylene derivative layer in the electroluminescent structure, wherein the hexaazatriphenylene derivative layer comprises a material containing six functional groups R, each functional group being independently or simultaneously selected from nitrile group (nitril-CN), hydrogen group (hydrogen-H), carboxyl group (carboxyl-COOH), carboxamide group (carboxamide-CONH)₂) Trifluoromethyl (trifluoromethyl, -CF)₃) And halogen radicals (halogen-halo).

Description

Application of Hexaazatriphenylene Derivatives in Organic Light-Emitting Devices

Technical field

The present invention relates to the application of a hexaazatriphenylene derivative, and in particular to the application of a hexaazatriphenylene derivative in an organic light-emitting element.

Background technique

The molecular orbitals of compounds can be divided into the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), where the energy difference between HOMO and vacuum level is equivalent to that of organic materials. The ionization potential, the energy difference from LUMO to vacuum level is equivalent to electron affinity. The organic light emitting device (OLED) contains different organic materials, and heterojunctions are formed between different organic materials. When the anode and cathode of the OLED are electrically connected to the positive and negative electrodes of the external electric field, the external electric field After applying a forward bias voltage, the potential barrier formed on the heterojunction of different organic materials can be used to confine electrons and holes near the heterojunction. Because the LUMO energy level difference between different organic materials is higher than the most HOMO energy level difference, electrons enter the HOMO of a specific organic material and combine with holes to release energy, part of which is in the form of radiation. And emit electric laser light in a specific wavelength range. However, in most organic semiconductor materials used in OLEDs, the mobility of holes is much higher than that of electrons, which makes it easy for holes and electrons in OLEDs to combine with the cathode side, and electrons and holes are too close to each other too early. The cathode side combination will reduce the current density in the OLED, thereby reducing the luminous efficiency of the organic light-emitting layer, and when the operating voltage of the OLED cannot be reduced, the high temperature inside the OLED will rapidly deteriorate the organic material and shorten the service life of the OLED.

Contents of the invention

The purpose of the present invention is to provide an application of a hexaazatriphenylene derivative in an organic light-emitting element, so as to effectively reduce the driving voltage of the element, improve the luminous efficiency of the element, improve the yield of the element manufacturing process, and increase the service life of the element to achieve environmental protection and energy saving. effect.

The present invention solves the technical problem by adopting the following technical solutions.

The invention proposes the application of a hexaazatriphenylene derivative in an organic light-emitting element. The organic light emitting device includes a substrate, an anode, a cathode and at least one electroluminescent structure. The substrate is made of light-transmitting material. The anode is electrically connected to the positive electrode of the external electric field and is suitable for providing hole current. The cathode is electrically connected to the negative electrode of the external electric field and adapted to provide electron current. The electroluminescence structure is arranged between the anode and the cathode, and at least one layer of hexaazatriphenylene derivative is formed in the electroluminescence structure, and the hexaazatriphenylene derivative layer of the hexaazatriphenylene derivative layer is The chemical formula of the substance is:

Wherein, R is a functional group (functional group), and the hexaazatriphenylene derivative includes six functional groups, and each functional group is independently or simultaneously selected from a nitrile group (nitrol, -CN), a hydrogen group (hydrogen, - H), carboxylic (-COOH), carboxamide (-CONH ₂ ), trifluoromethyl (trifluoromethyl, -CF ₃ ) and halogen (halogen, -halo).

The beneficial effect of the present invention is that because the hexaazatriphenylene derivatives with high electron affinity are used in organic light-emitting elements, the lowest unoccupied molecular orbital (LUMO) energy level value of the hexaazatriphenylene derivatives is relatively low. Low, so it has high electron affinity and good conductivity and other characteristics, it can be used as a material for the acceptor property (p-type) structure used to attract electrons and provide holes in semiconductor elements, and is used in organic light-emitting elements ( In the charge transport structure of OLED), the operating voltage of the organic light-emitting element can be greatly reduced, the luminous efficiency of the organic light-emitting element can be improved, and the service life of the element can be increased to achieve the effect of environmental protection and energy saving.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 is the chemical formula of hexaazatriphenylene derivatives.

FIG. 2 is a schematic cross-sectional view of the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a second embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a third embodiment of the present invention.

100, 200, 300: substrate 110, 230, 310: anode

120: the first electroluminescent structure 121: the first hole injection layer

122: The first hole transport layer 123: The first organic light-emitting layer

124: The first electron transport layer 125: The first electron injection layer

130: connection layer 140: second electroluminescent structure

141: Second hole injection layer 142: Second hole transport layer

143: Second organic light-emitting layer 144: Second electron transport layer

145: Second electron injection layer 150, 210, 330: Cathode

220, 320: Electroluminescence structure 221, 325: Electron injection layer

222, 324: electron transport layer 223, 323: organic light-emitting layer

224, 322: hole transport layer 225, 321: hole injection layer

Detailed ways

Figure 1 is the chemical formula of hexaazatriphenylene derivatives (HAT derivatives). Please refer to Figure 1, the hexaazatriphenylene derivative contains four benzene rings, of which three peripheral benzene rings surround the central benzene ring, each peripheral benzene ring shares two carbon atoms with the central benzene ring, and there are two A nitrogen atom replaces two carbon atoms, and two non-shared carbon atoms are connected to two functional groups (functional group) R, wherein each functional group R is independently or simultaneously selected from nitrile (nitril, -CN), hydrogen (hydrogen, -H), ve carboxyl (carboxylic, -COOH), carboxamide (-CONH ₂ ), trifluoromethyl (trifluoromethyl, -CF ₃ ) and halogen (halogen, -halo). Compared with the existing organic semiconductor materials, the lowest unoccupied molecular orbital (LUMO) energy level value of hexaazatriphenylene derivatives is lower, so it has higher electron affinity and good conductivity, and can be used as Materials used in semiconductor devices to attract electrons and provide hole acceptor properties (p-type) structure. Furthermore, hexaazatriphenylene derivatives with good acceptor properties (p-type) are suitable for the charge transport structure of organic light-emitting devices (OLEDs), which can greatly reduce the operating voltage of organic light-emitting devices and improve organic light-emitting luminous efficiency of the component.

FIG. 2 is a schematic cross-sectional view of the first embodiment of the present invention. Please refer to FIG. 2, the tandem organic light-emitting diode (Tandem OLED) includes a substrate 100, an anode 110 (anode), a first electroluminescent structure 120, a connecting layer 130 (connecting Layer), The second electroluminescent structure 140 and the cathode 150 (cathode). Several electroluminescent structures that can produce different colors of light are connected in series in Tandem OLED. After being excited by an external electric field, the light generated by the light generated by each organic light-emitting structure is mixed and emitted through the anode side or the cathode side to the outside. Tandem OLED is usually designed as a white organic light-emitting diode (WOLED), and its luminous efficiency can increase exponentially with the number of organic light-emitting structures in series. Moreover, the degradation rate is measured with the same current density value, and the Tandem OLED is the same as the general OLED. Since the initial brightness of the Tandem OLED is larger, the service life of the Tandem OLED is longer than that of the general Tandem OLED after being converted into an equal initial brightness value. But relatively, because there are more film layers in Tandem OLED, its driving voltage will also increase with the increase of the number of film layers. In this embodiment, the light generated by the Tandem OLED penetrates the anode side and emits to the outside. According to different purposes, the substrate 100 can be a transparent glass substrate or a transparent flexible substrate. The anode 110 is disposed on the substrate 100, and the material forming the anode 110 may be transparent conductive oxide (transparent conductive oxide, TCO), such as indium tin oxide (indium tin oxide, ITO). For the purpose of further increasing the electron affinity or adjusting the light transmittance of the anode 110 , other conductive material layers can be laminated on the light-transmitting conductive oxide layer to form the anode 110 . On the other hand, in order to make the electric laser generated by the organic light-emitting element only pass through the anode 110 and emit to the outside, the cathode 150 is formed of a metal conductive material with a high ionization potential and light reflection, such as lithium (Li), aluminum ( Al), magnesium (Mg), silver (Ag), or alloys of any combination of the above metals, or lamination of the above metals and other conductive materials such as light-transmitting conductive oxide layers or organic compounds, etc., to form the cathode 150 .

In this embodiment, the first electroluminescent structure 120 includes a first charge transport structure and a first organic light-emitting layer 123 (emitting material layer, EML), wherein the first charge transport structure may further include a first hole injection layer 121 (hole inject layer, HIL), the first hole transport layer 122 (hole transport layer, HTL), the first electron transport layer 124 (electron transport layer, ETL) and the first electron injection layer 125 (electron inject layer, EIL) , wherein the first hole injection layer 121 and the first hole transport layer 122 are sequentially disposed between the anode 110 and the first organic light-emitting layer 123, and the first electron transport layer 124 and the first electron injection layer 125 are sequentially disposed on the between the first organic light emitting layer 123 and the connection layer 130 . The second electroluminescent structure includes a second charge transport structure and a second organic light-emitting layer 143, wherein the second charge transport structure can further include a second hole injection layer 141, a second hole transport layer 142, a second electron transport layer layer 144 and a second electron injection layer 145, wherein the second hole injection layer 141 and the second hole transport layer 142 are sequentially arranged between the connection layer 130 and the second organic light-emitting layer 143, the second electron transport layer 144 and the The second electron injection layer 145 is sequentially disposed between the second organic light emitting layer 143 and the cathode 150 .

In detail, the process of Tandem OLED generating electric laser is that when the anode 110 is electrically connected to the positive electrode of the external electric field, holes are generated, and the first hole injection layer 121 arranged on the anode 110 injects the holes into the first hole. The hole transport layer 122, the first hole transport layer 122 transports holes to the first organic light-emitting layer 123, the connection layer 130 injects holes into the second hole injection layer 141, and the second hole injection layer 141 injects holes into the The second hole transport layer 142 , and the second hole transport layer 142 transports holes to the second organic light emitting layer 143 . On the other hand, the cathode 150 is electrically connected to the negative electrode of the external electric field to generate electrons, and the second electron injection layer 145 disposed on the cathode injects electrons into the second electron transport layer 144, and the second electron transport layer 144 transports electrons to the second electron transport layer 144. Two organic light emitting layers 130, the connection layer 130 injects electrons into the first electron injection layer 125, the first electron injection layer 125 injects holes into the first electron transport layer 124, and the first electron transport layer 124 transports electrons to the first organic light emitting layer Layer 123. Then, the electrons and holes transported to each organic light-emitting layer are combined to release energy and emit electric laser light in a specific wavelength range. It can be known from the above light emitting process that one of the most critical parts of the tandem organic light emitting device is the connection layer 130 disposed between the electroluminescent structures. The connection layer can also be called a charge generation layer (CGL), which can determine the number of holes and electrons combined in each organic light-emitting layer. Furthermore, organic materials applicable to OLEDs all have semiconducting properties, which are further divided into organic materials having donor properties (n-type) and organic materials having acceptor properties (p-type). Improve the phenomenon that the migration rate of holes in organic materials in OLEDs is higher than that of electrons, and avoid the premature combination of electrons and holes near the cathode side by reducing the hole transfer rate in the hole transport layer or improving electron injection transport layer. Especially in Tandem OLED, the connecting layer 130 of two electroluminescent structures in series must not only have the acceptor property for injecting holes and the donor property for injecting electrons, but also need to be able to properly balance the connection between the two sides in series. The mobility of holes and electrons in each electroluminescent structure.

In this embodiment, the hexaazatriphenylene derivative as shown in the chemical formula in Figure 1 is selected, and the hexaazatriphenylene derivative layer with acceptor properties (p-type) and the hexaazatriphenylene derivative layer with The n-type organic material layer is, for example, perylene or a lithium (Li)-containing organic compound, etc., and then combined to form a connection layer 130 with acceptor properties and donor properties (shown by a dotted line in the figure) , wherein the thickness of the hexaazatriphenylene derivative layer can be between 0.1 nanometer and 100 nanometers, and the preferred thickness is between 1 nanometer and 50 nanometers. The hexaazatriphenylene derivative is used as the acceptor material in the connection layer 130, which can reduce the electron transport barrier between the connection layer 130 and the second charge transport structure 145, 144, 142, 141, and then attracts electrons from the cathode 150. Electrons are injected into the second charge transport structure 145, 144, 142, 141 and holes can be injected into the second charge transport structure 145, 144, 142, 141 at the same time, so as to properly balance the mobility of holes and electrons in the second electroluminescent structure 140 . Therefore, a higher current density can be obtained with a lower driving voltage to improve the luminous efficiency of the Tandem OLED. It is worth mentioning that oxygen and moisture in the OLED process environment will react with the electrodes to produce oxides, resulting in reduced current density. In addition, most organic materials used in OLEDs have poor temperature resistance, and are prone to rapid deterioration in the temperature environment generated by continuous high operating voltage. Compared with existing materials, hexaazatriphenylene derivatives also have higher crystallinity and better temperature resistance. The higher crystallinity of hexaazatriphenylene derivatives can shield substances such as oxygen and moisture in the process environment, and the formation of a hexaazatriphenylene derivative layer on the electrode as an electron injection layer (shown by the dotted line in the figure) can Prevent oxides from being produced on electrodes, thereby improving the process yield of organic light-emitting devices. Hexaazatriphenylene derivatives have lower operating voltage and better temperature resistance. Forming a hexaazatriphenylene derivative layer on the organic light-emitting layer as an electron transport layer (shown by the dotted line in the figure) can delay deterioration The speed in turn increases the service life of the organic light-emitting element.

FIG. 3 is a schematic cross-sectional view of a second embodiment of the present invention. Please refer to FIG. 3, an inverted organic light-emitting diode (Inverted OLED) includes a substrate 200, a cathode 210 (cathode), an electroluminescent structure 220 and an anode 230 (anode). The anode 230 and the cathode 210 of the inverted OLED are respectively electrically connected to the positive pole and the negative pole of the external electric field. After the forward bias is applied by the external electric field, the electric laser light generated by the Inverted OLED is emitted through the side of the cathode 210 . The material of the cathode 210 may be a light-transmitting conductive material, and the material of the anode 230 may be a metallic conductive material capable of reflecting light. The electroluminescent structure 220 includes a charge transport structure and an organic light emitting layer 223 , wherein the charge transport structure may include an electron injection layer 221 , an electron transport layer 222 , a hole transport layer 224 and a hole injection layer 225 . The electron injection layer 221 and the electron transport layer 222 are sequentially disposed between the cathode 210 and the organic light-emitting layer 223 , and the hole transport layer 224 and the hole injection layer 225 are sequentially disposed between the organic light-emitting layer 223 and the anode 230 . The holes generated by the anode 230 are transported to the organic light emitting layer 223 through the hole injection layer 225 and the hole transport layer 224, and the electrons generated by the cathode 210 are transported to the organic light emitting layer 223 through the electron injection layer 221 and the electron transport layer 222 The electrons transmitted to the organic light-emitting layer 223 are combined with the holes to emit ve laser light in a specific wavelength range to penetrate the cathode 210 and emit to the outside. It is worth mentioning that in this embodiment, hexaazatriphenylene derivatives can be used not only as the material of the hole injection layer 225 (shown by the dotted line in the figure), but also as the material of the electron injection layer 221 or the electron transport layer 222. materials (shown in dotted lines in the figure).

FIG. 4 is a schematic cross-sectional view of a third embodiment of the present invention. Please refer to FIG. 4 , a side by side organic light-emitting diode (Side By Side OLED) includes a substrate 300 , an anode 310 , an electroluminescent structure 320 and a cathode 330 . The anode 310 and the cathode 330 of the Side By Side OLED are electrically connected to the positive pole and the negative pole of the external electric field respectively. After the forward bias is applied by the external electric field, the electric laser light generated by the Side By Side OLED penetrates the side of the anode 310 and emits to the outside. The electroluminescent structure 320 includes a charge transport structure and an organic light emitting layer 323 , wherein the charge transport structure may include a hole injection layer 321 , a hole transport layer 322 , an electron transport layer 324 and an electron injection layer 325 . The hole injection layer 321 and the hole transport layer 322 are sequentially disposed between the anode 310 and the organic light emitting layer 323 , and the electron transport layer 324 and the electron injection layer 325 are sequentially disposed between the organic light emitting layer 323 and the cathode 330 . In this embodiment, the hexaazatriphenylene derivative can be used as the material of the hole injection layer 321 (shown by the dotted line in the figure), and can also be used as the material of the electron injection layer 325 or the electron transport layer 324 (shown in the figure). shown by the dotted line).

In summary, the use of hexaazatriphenylene derivatives in organic light-emitting devices as materials for connection layers or charge transport structures, or the use of hexaazatriphenylene derivatives in organic light-emitting devices as connection layers and charge transport structures at the same time The material of the transmission structure can effectively reduce the driving voltage of the component, improve the luminous efficiency of the component, improve the yield rate of the component process, and increase the service life of the component to achieve the effect of environmental protection and energy saving.

Claims (11)

1. An application of a hexaazatriphenylene derivative in an organic light-emitting element, the organic light-emitting element includes a substrate, an anode, a cathode and at least one electroluminescent structure, the substrate is made of light-transmitting materials, and the anode and an external electric field The positive electrode of the external electric field is electrically connected, and is suitable for providing hole current, and the cathode is electrically connected with the negative electrode of the external electric field, and is suitable for providing electron current, and the at least one electroluminescent structure is arranged between the anode and the cathode Among them, it is characterized in that at least one layer of hexaazatriphenylene derivatives is formed in the electroluminescent structure, wherein the chemical formula of the hexaazatriphenylene derivatives in the hexaazatriphenylene derivative layer is: :

Wherein, R is a functional group, and the hexaazatriphenylene derivative contains six functional groups, and the six functional groups are independently or simultaneously selected from nitrile (nitrol, -CN), hydrogen (hydrogen, -H ), carboxylic (-COOH), carboxamide (-CONH ₂ ), trifluoromethyl (trifluoromethyl, -CF ₃ ) and halogen (halogen, -halo). 2. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 1, wherein the anode is made of a light-transmitting conductive material and arranged on the substrate; the at least one electroluminescent The structure includes a first electroluminescent structure and a second electroluminescent structure, the first electroluminescent structure includes a first organic light-emitting layer and a first charge transport structure, and the first organic light-emitting layer is configured on the first charge transport structure In the middle; the second electroluminescent structure includes a second organic light emitting layer and a second charge transport structure, and the second organic light emitting layer is disposed in the second charge transport structure; the cathode is made of a conductive material that can reflect light. 3. The application of the hexaazatriphenylene derivative in an organic light-emitting device according to claim 2, wherein the organic light-emitting device further comprises at least one connection layer, and the first charge transport structure is arranged on the anode between the connection layer and suitable for transporting the hole current and the electron current to the first organic light-emitting layer, the second charge transport structure is arranged between the connection layer and the cathode and suitable for transporting the electrons The current and the hole current flow to the second organic light-emitting layer. 4. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 3, wherein the connection layer comprises the hexaazatriphenylene derivative layer and is suitable for injecting the holes current to the second charge transport structure. 5. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 3, wherein the first charge transport structure comprises the hexaazatriphenylene derivative layer and a first hole The transport layer, the hexaazatriphenylene derivative layer is configured on the anode, and is suitable for injecting the hole current into the first hole transport layer. 6. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 3, wherein the second charge transport structure comprises the hexaazatriphenylene derivative layer and a second electron transport layer, the hexaazatriphenylene derivative layer is disposed on the cathode, and is suitable for injecting the electron current into the second electron transport layer. 7. The application of the hexaazatriphenylene derivative in an organic light-emitting device according to claim 3, wherein the second charge transport structure comprises a second electron injection layer and the hexaazatriphenylene derivative layer, the second electron injection layer is configured on the cathode, and is suitable for injecting the electron current into the hexaazatriphenylene derivative layer, and the hexaazatriphenylene derivative layer is configured on the second electron injection layer and the second organic light-emitting layer, and is suitable for transmitting the electron current to the second organic light-emitting layer. 8. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 1, wherein the anode is a conductive material that can reflect light and the cathode is a light-transmitting conductive material, or the anode The cathode is a light-transmitting conductive material and the cathode is a conductive material that can reflect light. The electroluminescent structure includes an organic light-emitting layer and a charge transport structure. The organic light-emitting layer is configured in the charge transport structure. 9. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 8, wherein the charge transport structure comprises the hexaazatriphenylene derivative layer and a hole transport layer, the The hexaazatriphenylene derivative layer is disposed on the anode and is suitable for injecting the hole current into the hole transport layer. 10. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 8, wherein the charge transport structure comprises the hexaazatriphenylene derivative layer and an electron transport layer, and the hexaazatriphenylene derivative layer and an electron transport layer, The azatriphenylene derivative layer is disposed on the cathode and is suitable for injecting the electron current into the electron transport layer. 11. The application of the hexaazatriphenylene derivative in an organic light-emitting element according to claim 8, wherein the charge transport structure comprises an electron injection layer and the hexaazatriphenylene derivative layer, and the electron The injection layer is arranged on the cathode, and is suitable for injecting the electron current into the hexaazatriphenylene derivative layer, and the hexaazatriphenylene derivative layer is arranged between the electron injection layer and the organic light-emitting layer , and is suitable for transmitting the electron current to the organic light-emitting layer.

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