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EP-4044237-B1 - FULL-COLOR µLED MICRO-DISPLAY DEVICE WITHOUT ELECTRICAL CONTACT, AND METHOD FOR MANUFACTURING SAME

EP4044237B1EP 4044237 B1EP4044237 B1EP 4044237B1EP-4044237-B1

Inventors

  • ZHANG, YONGAI
  • CHEN, Shiyao
  • GUO, TAILIANG
  • ZHOU, Xiongtu
  • WU, Chaoxing
  • Lin, Zhixian
  • SUN, LEI
  • YAN, QUN

Dates

Publication Date
20260506
Application Date
20200831

Claims (9)

  1. A full-color µLED micro-display device without electrical contact, comprising: a lower transparent substrate (100), an upper transparent substrate (200), a control module, a frame-sealing body (500) connecting the upper transparent substrate and lower transparent substrate, a blue µLED grain, a wavelength down-conversion light-emitting layer (300), a reflective layer (110) arranged on a surface of the lower transparent substrate, characterized in that it also comprises a vent (600) arranged on the upper transparent substrate, a color filter film (700) arranged on the upper transparent substrate, a diffusion layer (210) arranged on a surface of the upper transparent substrate, a lower driving electrode (120) arranged above the lower transparent substrate, and an upper driving electrode (220) arranged under the upper transparent substrate, the upper driving electrode (220) and lower driving electrode (120) are separately arranged on both sides of the blue µLED grain, and the wavelength down-conversion light-emitting layer (300) is arranged between the upper driving electrode (220), the lower driving electrode (120) and the blue µLED grain; the upper driving electrode (220) and the lower driving electrode (120) are in no direct electrical contact with the blue µLED grain, and a independent space is formed; the control module is electrically connected with the upper driving electrode (220) and the lower driving electrode (120) separately, the control module provides alternating driving signals for the upper and lower driving electrodes, and forms a driving electric field between the upper driving electrode (220) and the lower driving electrode (120); the driving electric field controls the recombination of electrons and holes of the µLED grain and emits a first light source, the first light source is converted into a second light source after passing through the wavelength down-conversion light-emitting layer (300), and the first light source is mixed, after passing through the reflective layer (110), with the second light source by the diffusion layer (210) to form a uniform third light source; the third light source achieves full-color µLED micro-display after passing through the color filter film (700); the blue grain is composed of multiple blue µLED chips connected in series along the vertical direction, or composed of multiple blue µLED chips connected in parallel along the horizontal direction, or composed of multiple blue µLED chips randomly stacked.
  2. The full-color µLED micro-display device without electrical contact according to claim 1, characterized in that , the color filter film (700) is arranged on the upper surface of the upper transparent substrate (200), and corresponds to the upper driving electrode (220); the color filter film (700) sequentially constitutes unit R for red light display, unit G for green light display, and unit B for blue light display along the direction of the upper driving electrode (220); the unit R, unit G and unit B are arranged at equal intervals with black barriers directly filled between them.
  3. The full-color µLED micro-display device without electrical contact according to claim 1, characterized in that , the blue µLED chip comprises a p-type semiconductor material, a light-emitting structure and an n-type semiconductor material, and the p-type semiconductor material, the light-emitting structure and the n-type semiconductor material are stacked along the vertical direction to form a semiconductor junction.
  4. The full-color µLED micro-display device without electrical contact according to claim 3, characterized in that , the semiconductor junction comprises one of, or a combination of a single semiconductor junction, a pair of semiconductor junctions, and multiple semiconductor junctions; the P-type semiconductor material has a thickness of 1 nm-2.0 µm, the light-emitting structure has a thickness of 1 nm-1.0 µm, and the N-type semiconductor material has a thickness of 1 nm-2.5 µm.
  5. The full-color µLED micro-display device without electrical contact according to claim 1, characterized in that , the upper driving electrode (220) is composed of multiple line electrodes in parallel to each other, and is arranged on a surface of the upper transparent substrate (220) along the horizontal direction of the µLED grain; the lower driving electrode (120) is composed of multiple line electrodes in parallel to each other, and is arranged on a surface of the lower transparent substrate (100) along the vertical direction of the µLED grain, and the upper electrode and the lower electrode are perpendicular to each other with space between them, and a independent space can be formed.
  6. The full-color µLED micro-display device without electrical contact according to claim 1, characterized in that , the wavelength down-conversion light-emitting layer (300) may be arranged on surfaces of the upper driving electrode (220) and the lower driving electrode (120), or may be arranged on an outer surface of the µLED grain, or may be mixed and wrapped with the µLED grain, and arranged within the independent space formed by the upper driving electrode (220) and the lower driving electrode (120); the wavelength down-conversion light-emitting layer (300) is a yellow quantum dot material, or may be a yellow phosphor material, or may be a material mixing yellow quantum dots and yellow phosphor; the wavelength down-conversion light-emitting layer (300) excites, under the irradiation of light from the first light source emitted by the blue µLED grain, the second light source with a longer wavelength, and the second light source is yellow light.
  7. The full-color µLED micro-display device without electrical contact according to claim 1, characterized in that , the control module can provide an alternating voltage whose amplitude and polarity change with time; the waveform of the alternating voltage is a composite waveform of one or more of sine wave, triangle wave, square wave and pulse; the frequency of the alternating voltage is 1Hz-1000MHz.
  8. A manufacturing method based on the full-color µLED micro-display device with electrical contact according to any one of claims 1-7, characterized in that , the method is implemented according to the following steps: Step S1, provide a upper transparent substrate (200) with a vent (600), and sequentially deposit a diffusion layer (210) and an upper driving electrode (220) on one surface of the upper transparent substrate (200) by means of physical vapor deposition or chemical vapor deposition or printing or inkjet printing; the diffusion layer (210) mixes the first light source and the second light source and turns them into a third light source that emits uniform light; the upper driving electrode (220) is a transparent electrode, the material of which comprises graphene, indium tin oxide, carbon nanotube, silver nanowire, copper nanowire and a combination thereof; Step S2, prepare a color filter film (700) on a surface of the upper transparent substrate (200) by means of photolithography or screen printing, the color filter film unit R, unit G and unit B are in one-to-one correspondence with the upper driving electrode (220); the unit R, unit G and unit B are arranged at equal intervals with black barriers directly filled between them; Step S3, provide a lower transparent substrate (100), and deposit a reflective layer (110) and a lower driving electrode (120) on a surface of the lower transparent substrate (100) by means of physical vapor deposition or chemical vapor deposition or printing or inkjet printing; the reflective layer (110) reflects back the first light source, the second light source, and the third light source formed after the first light source and the second light source are mixed, thereby improving the device efficiency; the material of the lower driving electrode (120) comprises gold, silver, aluminum, copper, and an alloy or laminated structure thereof; Step S4, coat the frame-sealing body (500) around the lower transparent substrate (100) by means of screen printing, inkjet printing or scrape coating; Step S5, provide a wavelength down-conversion light-emitting layer (300): coat surfaces of the upper driving electrode (220) and the lower driving electrode (120) with a layer of a wavelength down-conversion light-emitting layer (300) by means of screen printing or inkjet printing or spray coating or spin coating; Step S6, provide a blue µLED grain: coat a surface of the wavelength down-conversion light-emitting layer (300) with a layer of blue µLED chip by means of inkjet printing or scrape coating or spraying; Step S7, align the upper and lower transparent substrates for packaging, and degas via the vent (600) for sealing off; and Step S8, provide a control module; the control module is electrically connected with the upper driving electrode (220) and the lower driving electrode (120) separately, the control module provides alternating driving signals for the upper driving electrode (220) and the lower driving electrode (120), and forms a driving electric field between the upper driving electrode (220) and the lower driving electrode (120); the driving electric field controls the recombination of electrons and holes of the µLED grain and emits a first light source, the first light source is converted into a second light source after passing through the wavelength down-conversion light-emitting layer (300), which are mixed to form a uniform third light source after passing through the reflective layer (110) and the diffusion layer (210), and change into red light, green light, and blue light after passing through the color filter film (700), thereby achieving full-color µLED micro-display.
  9. A manufacturing method based on the full-color µLED micro-display device with electrical contact according to any one of claims 1-7, characterized in that , the method is implemented according to the following steps: Step S1, provide a upper transparent substrate (200) with a vent (600), and sequentially deposit a diffusion layer (210) and an upper driving electrode (220) on one surface of the upper transparent substrate (200) by means of physical vapor deposition or chemical vapor deposition or printing or inkjet printing; the diffusion layer (210) mixes the first light source and the second light source and turns them into a third light source that emits uniform light; the upper driving electrode (220) is a transparent electrode, the material of which comprises graphene, indium tin oxide, carbon nanotube, silver nanowire, copper nanowire and a combination thereof; Step S2, prepare a color filter film (700) on a surface of the upper transparent substrate (200) by means of photolithography or screen printing, the color filter film unit R, unit G and unit B are in one-to-one correspondence with the upper driving electrode (220); the unit R, unit G and unit B are arranged at equal intervals with black barriers directly filled between them; Step S3, coat the frame-sealing body (500) around the lower transparent substrate (100) by means of screen printing, inkjet printing or scrape coating; Step S4, provide a lower transparent substrate (100), and deposit a reflective layer (110) and a lower driving electrode (120) on a surface of the lower transparent substrate (100) by means of physical vapor deposition or chemical vapor deposition or printing or inkjet printing; the reflective layer (110) reflects back the first light source, the second light source, and the third light source formed after the first light source and the second light source are mixed, thereby improving the device efficiency; the material of the lower driving electrode (120) comprises gold, silver, aluminum, copper, and their alloy or laminated structure; Step S5, provide a blue µLED grain; Step S6, provide a wavelength down-conversion light-emitting layer (300): evenly mix the wavelength down-conversion light-emitting layer (300) and the blue µLED chip, mix and wrap the µLED grain and the wavelength down-conversion light-emitting layer (300) together, and arrange them on a surface of the lower driving electrode (120) by means of screen printing or inkjet printing or spray coating or spin coating; Step S7, align the upper and lower transparent substrates for packaging, and degas via the vent (600) for sealing off; and Step S8, provide a control module; the control module is electrically connected with the upper driving electrode (220) and the lower driving electrode (120) separately, the control module provides alternating driving signals for the upper driving electrode (220) and the lower driving electrode (120), and forms a driving electric field between the upper driving electrode (220) and the lower driving electrode (120); the driving electric field controls the recombination of electrons and holes of the µLED grain and emits a first light source, the first light source is converted into a second light source after passing through the wavelength down-conversion light-emitting layer (300), which change into red light, green light, and blue light after passing through the reflective layer (110) and the diffusion layer (210) and passing through the color filter film (700), thereby achieving full-color µLED micro-display.

Description

BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates to the field of integrated semiconductor display, and in particular, to a full-color µLED micro-display device without electrical contact and a manufacturing method therefor. 2. Description of Related Art In the field of flat panel display technologies, micron LED display (referred to as µLED display) refers to the miniaturization of conventional LED to form a micron-pitch LED array to achieve ultra-high-density pixel resolution. The µLED display has a self-luminous property, and compared with OLED and LCD displays, the µLED display features low power consumption, high brightness, ultra-high definition resolution, high color saturation, faster response speed, longer service life and higher work efficiency. In addition, the µLED display is the only display device with high luminous efficiency and low power consumption that can integrate driving, light emission, and signal transmission, and realize ultra-large-scale integrated light-emitting units. Due to its high density, small size, and super pixel properties, the µLED display will lead the third-generation display technologies featuring high-fidelity, interactive and personalized displays. Due to the combination of the two major technical features of LCD and LED, the product performance is much higher than the existing TFT-LCD and OLED, and may be widely applied in flexible displays, vehicle displays, transparent displays, large-area displays, wearable displays, AR/VR and other fields. However, due to the problems such as size and quantity, there are still a series of technical difficulties in bonding, transfer, driving, colorization and the like with respect to micron LED integration. At present, the full-color µLED display is generally epitaxially grown on a GaN or GaAs substrate by means of metal organic chemical vapor deposition (MOCVD), the red, green and blue tricolor µLED chips are prepared using many processes, and the tricolor µLED chips and driving chips are bound on a circuit substrate using the chip transfer and bonding processes to form full-color tricolor display pixels. Such a technique requires precise electrical contact between the driving electrode and the driving module in the µLED chip through precise alignment and bonding, and requires a huge number of µLED grains to pick, place and assemble; with respect to the colorization techniques, it may also be achieved through color conversion, optical prism synthesis, and emission of light with different wavelengths by controlling the structure and size of the LED. The color conversion of blue LED + red and green quantum dots is the mainstream technical route to achieve full-color µLED display. In the prior art processes, using the quantum dot technology to achieve Micro-LED full-color display is a common process optimization means, and there are now many available process technologies and preparation solutions. Chinese patents CN106356386A, CN108257949A, CN109256455A achieve full-color display by filling blue µLED chips with red quantum dot and green quantum dot units, but the blue µLED chips require cathodes and anodes to be made, and quantum dots need to be patterned as well, while the µLED chip is bonded with the driving electrode chip after passing through massive transfer, and the blue µLED chip can be driven to emit light only after the electrode is in contact, so as to achieve full-color display, which results in longer cycle for manufacturing a µLED device and high production cost. Patent CN 109256456 A discloses a method for realizing Micro A light emit diode (LED) exhibits a microstructure with improve light efficiency and reduced tampering, and a method of manufacturing that same,comprising a substrate, a transparent substrate, an LED chip array, a microlens array, an inverted trapezoidal microstructure array, and an enclosure; Wherein the inverted trapezoidal microstructure is aligned with the LED chip one by one and packaged together; The top of the inverted trapezoidal microstructure is a distributed Bragg reflector, the outer periphery is a reflector, and the inner isfilled with a quantum dot luminescent layer. The microlens corresponds to the inverted trapezoidal microstructure one by one and adheres to the microstructure as a whole. The invention can not only use the blue LED chip to excite the red/green quantum dot layer and convert the red/green quantum dot layer to the red/green light, but also realize the Micro-Color conversion of LED display; At the same time, by using the distributed Bragg reflector in microstructure, The light efficiency of Micro-LED display can also be improved by utilizing the reflective layer and microlens array in the microstructure to prevent the light interference of adjacent pixels and to realize the extraction of light efficiency and the reduction of tampering Micro-LED display. Patent US2017/025399 A1 discloses a display apparatus and a method of manufacturing the sam