Double side display organic electroluminescence light emitting device

Double-sided display organic electroluminescence device

(1) Technical Field The present invention relates to an organic light-emitting diode (OLED) device, and more specifically to an organic light-emitting diode (OLED) device that can display on both sides.

(2) Background technology Compared with the current mainstream liquid crystal display (Liquid Crystal Display; LCD), Organic Light-Emitting Diode; OLED) devices have greater advantages: in terms of volume, since OLEDs emit light by themselves, they do not require backlights and external lighting resources, so they are lighter than LCDs. Generally, an OLED panel is about 1mm to 2mm thick, which is usually one-third of that of ordinary color LCDs, and half thinner than most black and white LCDs. It is easy to create 3mm to 4mm displays, and OLEDs are excellent It can be folded and bent, which makes its application range very wide. In terms of viewing angle, because OLED and LCD have different light sources (the former is a radioactive substance, the latter is a mapping substance), OLED has a very large visible The angle, row and column can reach more than 160 degrees, and there is no distortion, which solves the inherent defect of LCD's small viewing angle; in terms of response time, because OLED is in a solid state, its response speed is 100 to 1000 times faster than LCD. This makes it possible to completely get rid of the delay problem of LCD, and display the picture faster and smoother; in terms of efficiency, OLED only needs a voltage of 2V to 10V to fully make it reach the best working condition, without the backlight, it is more than LCD has lower power consumption and can improve battery life. In terms of cost, OLED is an artificial ultra-thin organic thin film layer, which does not require to be completed in a vacuum environment, and does not contain non-fixed raw materials, so its manufacturing cost is low. At the same time, there is no need for expensive semiconductor manufacturing processes.

The simplest OLED principle is shown in Figure 1. In the OLED 30, an organic light-emitting layer 34 with light-emitting characteristics is sandwiched between the cathode and anode of the power supply. By applying a voltage 38, holes 35 are injected from the hole injection region 38. The electrons 31 are injected from the cathode and are transported through the electron transport layer 33. The electrons 31 and the holes 35 are combined during the transport, so that the organic light-emitting molecules 32 are in an excited state, and then release energy When returning to the ground state, part of the energy will be released in the form of photons 36 through the internal transformation, thereby achieving light emission.

The industry generally uses metal electrodes as the cathode of the OLED, while using transparent conductive glass (Indium-TinOxide; ITO) as the anode. As shown in FIG. 2, the basic structure of the existing OLED device 40 includes a glass substrate (Glass Substrate) 41, an ITO anode (ITO Anode) 42, a hole injection layer (HIL) 43, and a hole transmission layer. Layer (Hole Transporting Layer; HTL) 44, organic light-emitting layer (EmittingLayer; EML) 45, electron transporting layer (Electron Transporting Layer) 46, and metal electrode cathode (MetalCathode) 47. The molecules in the organic light-emitting layer recover from the excited state to the ground state. The released energy is converted into light energy and diffuses outward from the glass substrate.

As mentioned above, the prior art OLEDs can only emit light from the transparent ITO anode side, while the metal electrode cathode side can only be used as the back side of the OLED device, such as US Patent Publication No. 6,586,764 and US Patent Application No. 20020094422. And the OLED devices disclosed in Chinese Patent Application No. 02109031.9, etc., can only achieve single-sided display. In many cases, users want to display information from the front of the OLED device and the same information from the back, such as handheld communication devices, notebook computers, large outdoor display screens, etc. However, the prior art OLED devices obviously cannot Meet such requirements.

In order to meet the above requirements of users, OLED devices with double-sided displays have begun to appear on the market. However, the double-sided display OLED device adopts a double-layer structure design, that is, two sets of OLED display units are combined in a back to back manner to realize the double-sided display of the OLED device. This design makes the structure of the double-sided display device more complicated, the thickness and weight are increased, and the cost is greatly increased.

(3) Summary of the invention One of the main objectives of the present invention is to provide an Organic Light-Emitting Diode (OLED) device with a simple structure.

Another object of the present invention is to provide a double-sided display OLED device with a smaller thickness and lighter weight.

Another object of the present invention is to provide a double-sided display OLED device with lower manufacturing cost.

In order to achieve the above objective, the technical solution of the present invention is realized as follows: a double-sided display organic electroluminescence (Organic Light-Emitting Diode; OLED) device, which includes at least one transparent conductive glass (Indium-Tin Oxide; ITO). ) Anode, a cathode opposite to the transparent conductive glass anode and an organic light-emitting layer arranged between the transparent conductive glass anode and the cathode. A driving voltage is applied between the transparent conductive glass anode and the cathode to activate the organic light-emitting layer The light is characterized in that the cathode is also made of transparent conductive glass.

The double-sided display organic electroluminescence device further includes: a hole injection layer (HIL) and a hole transport layer (HTL) are sequentially arranged between the transparent conductive glass anode and the organic light emitting layer The transparent conductive glass cathode and the organic light-emitting layer are provided with an electron transport layer (Electron TransportingLayer); the transparent conductive glass anode and the transparent conductive glass cathode are respectively provided with a glass substrate on the outer side. In addition, the double-sided display organic electroluminescent device may further include embedded software and its corresponding driving circuit for mirroring the image on one side of the double-sided display organic electroluminescent device.

The main feature of the present invention is: replacing the opaque metal cathode in the prior art with a transparent conductive glass cathode, thereby overcoming the shortcomings that the prior art OLED device can only emit light on one side, or can only achieve double-sided display in a double-layer structure. .

It can be seen that the double-sided display organic electroluminescence device provided by the present invention has the following advantages: (a) The structure is simple, only the metal cathode in the prior art OLED device needs to be replaced with a transparent conductive glass cathode, and the related circuit does not need to be implemented. Significant changes; (b) Smaller thickness and lighter weight. Since the double-layer structure in the OLED device in the prior art is not required, the thickness and weight will hardly increase; and (c) The manufacturing cost is lower, and no Two sets of OLED display units are required, which effectively reduces costs.

(4) Description of the drawings Fig. 1 is a light-emitting principle diagram of an Organic Light-Emitting Diode (OLED) device in the prior art.

Fig. 2 is a schematic diagram of the basic structure of an OLED device in the prior art.

FIG. 3 is a schematic diagram of the basic structure of the double-sided display OLED device of the present invention.

(V) Specific implementation The present invention will be described in detail below with reference to the accompanying drawings.

Please refer to Figure 3, the double-sided display organic electroluminescence (Organic Light-Emitting Diode; OLED) device 50 of the present invention at least includes a transparent conductive glass (Indium-Tin Oxide; ITO) anode 52, one opposite to the transparent ITO anode The transparent ITO cathode 57, and the organic light emitting layer (EML) 55 disposed on the ITO anode 52 and the ITO cathode 57.

The double-sided display OLED device 50 further includes a hole injection layer (HIL) 53 and a hole transporting layer (HTL) 54 disposed between the ITO anode 52 and the organic light-emitting layer 55, The hole injection layer 53 is adjacent to the ITO anode, the hole transport layer is adjacent to the organic light-emitting layer 55; an electron transporting layer (Electron Transporting Layer) 56 disposed between the ITO cathode and the organic light-emitting layer 55 .

The double-sided display OLED device 50 further includes glass substrates 51, 57 disposed on the outside of the ITO anode 52 and the ITO cathode 57, respectively. The visible light emitted by the organic light-emitting layer 55 can pass through the two glass substrates 51, 57 from the front and A double-sided display is realized on the back. A driving voltage 59 is applied between the ITO anode 52 and the ITO cathode 57.

The glass substrates 51 and 57 can also be flexible substrates to increase the flexibility of the double-sided display OLED device 50. The ITO anode 52 is plated on the glass substrate 51 as the hole emitting material of the double-sided display OLED device 50. On the ITO anode 52, a layer of phthalocyanine can be further covered to passivate the ITO anode 52 and provide higher stability. Driven by the driving voltage 59, usually 2-10 volts, the holes generated by the ITO anode 52 are injected from the hole injection layer and transferred from the hole transport layer 54 to the organic light emitting layer 55. The hole transport layer 54 is made of a hole transport material with high mobility under the driving of an electric field. In order to prevent the hole transport material from recrystallization after long-term aging, The hole transport material should preferably be selected to have high heat resistance stability (high glass transition temperature Tg), relatively small energy barrier between the ITO anode 52, and a good thin film that can be formed naturally. Type (thin-film morphology). The organic light-emitting layer 55 can be made of low-molecular or high-molecular organic light-emitting materials containing conjugated chemical structures, using thermal evaporation (for low-molecular organic light-emitting materials) or spin coating (for high-molecular organic light-emitting materials). Material) is formed on the hole transport layer 54.

In the same way, the ITO cathode 57 is also plated on the glass substrate 57, opposite to the ITO anode 52, as the electron emission material of the double-sided display OLED device 50. An electron transport layer 56 is arranged between the ITO cathode 57 and the organic light-emitting layer 55. Under the drive of a voltage 59, the electrons emitted by the ITO cathode 57 are injected into the electron transport layer 56 and are transported to the electron transport layer 56 by the electron transport layer 56. Organic light emitting layer 55.

As described above, under the driving of the voltage 59, holes and electrons are injected from the ITO anode 52 and the ITO cathode 57 into the hole transport layer 53 and the electron transport layer 56, respectively, and the electrons and holes pass through the hole transport layer 53 respectively. And the electron transport layer 56 migrate to the organic light-emitting layer 55 and meet in the organic light-emitting layer 55, thereby exciting the molecules of the organic light-emitting material forming the organic light-emitting layer 55, and the molecules in the organic light-emitting layer return to the ground state from the excited state The released energy is converted into visible light, which can simultaneously diffuse outward from both sides of the ITO anode 52 and the ITO cathode, thereby realizing the double-sided display of the OLED device 50.

In the present invention, both the anode and cathode of the OLED device are made of transparent ITO, so that the visible light emitted by the organic light-emitting layer can diffuse from both sides of the OLED device to achieve double-sided display, which overcomes the prior art Due to the use of an opaque metal cathode, the metal cathode will reflect the visible light emitted by its organic light-emitting layer, so that the light can only diffuse from the side of the ITO anode, that is, it can only emit light on one side.

In addition, since in the above-mentioned double-sided display, the images observed from both sides of the OLED device 50 are the same, this will cause the direction of the image displayed on one side to be opposite to the normal image direction. In a further embodiment of the double-sided display organic electroluminescent device of the present invention, it can optionally include embedded software and its corresponding driving circuit to realize the mirror image of the image on one side of the double-sided display organic electroluminescent device , So that the image direction of the surface is the same as the normal image direction. Since the related software for realizing the mirror image and its corresponding driving circuit are relatively mature in the prior art, it will not be repeated here.