μOLED Direct Bonding for High Resolution and Brightness
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Solution Overview
Problem
Current micro-OLED (μOLED) devices face challenges in achieving high resolution beyond 2,000 pixels per inch and brightness above 5,000 nits due to manufacturing difficulties with silicon substrates, low yield, and vulnerability of color filter layers to high brightness, which limits their suitability for next-wave AR/MR and autostereoscopic 3D display applications.
Innovation Solution
The μOLED device architecture is modified by forming the OLED layer on one substrate and the TFT circuit on another, with direct bonding between the substrates, allowing for improved resolution and brightness by decoupling the resolution requirements of the TFT and OLED layers, and using quantum dot layers or RGB direct patterning for color transformation, which can withstand high brightness without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the white OLED, color filter, and thin film encapsulating layers are integrated onto one single Si substrate, then the device structure is compact, but the manufacturing yield becomes very low
Solution Approach 1:
The device is divided into two separate substrates: a first substrate containing the white OLED and thin film encapsulating layers, and a second substrate containing the color filter and TFT circuits. These substrates are manufactured independently and then bonded together, allowing each component to be optimized and manufactured separately to improve overall yield while maintaining compact integration.
2Device complexity
If the color filter layer is used to transform white light to RGB colors, then the device structure is simplified, but the layer becomes vulnerable to high brightness above 5,000 nits
Solution Approach 1:
A quantum dot layer is introduced as an intermediary between the white OLED and the color filter. The quantum dots convert the white light into high-brightness RGB colors that can withstand intensities above 5,000 nits, protecting the color filter layer from degradation while maintaining the simplified color transformation structure.
3Manufacturing precision
If the μOLED resolution is increased beyond 2,000 ppi for AR applications, then the display quality improves, but the manufacturing difficulty increases
Solution Approach 1:
The high-resolution display is achieved by segmenting the manufacturing process across two substrates. The first substrate manufactures the white OLED with precise pixel positioning, while the second substrate manufactures the color filter and TFT circuits separately. This segmentation allows each substrate to be manufactured at optimal resolution levels independently, making ultra-high resolution beyond 2,000 ppi more manufacturable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables μOLED devices to achieve resolutions beyond 2,000 ppi and brightness up to 100,000 nits, enhancing their performance for next-wave display applications like AR/MR and autostereoscopic 3D displays without the yield and manufacturing issues of traditional μOLEDs.
Implementation Method 1
an OLED layer and optionally a color-transformation layer, the OLED layer being formed on a selected one of the first and second substrates
Implementation Method 2
The bonding surface of the first substrate and the first surface of the second substrate are in direct bonding
Data Source
AI summary
An OLED device includes: a first substrate having a bonding surface; a second substrate having a first surface; a coloring unit including an OLED layer and optionally a color-transformation layer, the OLED layer being formed on a selected one of the first and second substrates, the color-transformation layer being formed on the second substrate; and a pixel circuit with TFT functions disposed on the first substrate and coupled to the OLED layer. The bonding surface of the first substrate and the first surface of the second substrate are in direct bonding.