Top-Emitting White OLED With Gradually-Varying Cavity Length
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Solution Overview
Problem
Top-emitting white OLEDs suffer from a significant decrease in efficiency and color purity due to the microcavity effect, which worsens with increasing viewing angles, affecting high-precision panel displays.
Innovation Solution
A top-emitting white OLED device with a gradually-varied cavity length in the organic layer, corresponding to the range from red to blue light wavelengths, and a periodically fluctuated structure on the electrode layers, including a lattice structure with bumps and pits, to enhance light intensity and reduce color cast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a top-emitting white OLED structure is used to improve aperture ratio and device integration, then the aperture ratio and TFT circuit design flexibility are improved, but the microcavity effect causes efficiency to decrease significantly at large viewing angles
Solution Approach 1:
The patent applies local quality by creating different cavity lengths in different regions of the OLED device. The first region has a first cavity length optimized for certain wavelengths, while the second region has a second cavity length optimized for other wavelengths. This spatial variation in cavity structure allows different parts of the device to handle different portions of the spectrum independently, reducing the overall microcavity effect's negative impact on viewing angle performance.
Solution Approach 2:
The patent segments the OLED device into multiple regions with different cavity lengths. By dividing the emission area into distinct zones (first region and second region), each with tailored optical cavity characteristics, the device can maintain better color consistency and efficiency across different viewing angles. This segmentation approach addresses the microcavity effect by distributing its impact across multiple optimized zones rather than a single uniform structure.
2Ease of manufacture
If the OLED structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but color purity and spectrum control are compromised
Solution Approach 1:
The patent utilizes parameter changes by varying the cavity length parameter across different regions of the device. The first cavity length and second cavity length are specifically tuned to optimize emission characteristics for different wavelength ranges. This parameter variation approach allows for improved color purity and spectrum control through straightforward structural modifications rather than complex multi-layer designs, maintaining ease of manufacture while achieving precise optical control.
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
The solution enhances light intensity and minimizes color cast effects across various viewing angles, improving the microcavity effect and external quantum efficiency, making it suitable for large-size OLED displays.
Implementation Method 1
the OLED generally is of a strong microcavity effect. Due to the microcavity effect, an electroluminescence spectrum of the OLED may vary with a viewing angle
Implementation Method 2
A surface of the first electrode layer facing the organic layer has a periodically fluctuated structure
Data Source
AI summary
The present disclosure provides a top-emitting white organic light emitting diode (OLED) device, a method for manufacturing the same and a display apparatus. The OLED device includes a plurality of pixel units on a substrate, wherein each pixel unit includes a first electrode layer, an organic layer and a second electrode layer arranged subsequently on the substrate from bottom up, and the organic layer in each pixel unit includes a gradually-varied cavity length, and the gradually-varied cavity length corresponds to a range from a wavelength of red light to a wavelength of blue light.