OLED Pixel Structure Using Resonance and Total Reflection for Color Balance
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Solution Overview
Problem
In organic EL display devices with fine pixel pitches, achieving color balance is difficult due to variations in light emission characteristics of stacked light emitting layers, especially in reflector structures, leading to decreased light extraction efficiency.
Innovation Solution
A display device design featuring lower electrodes, partition walls with varying widths, and an organic layer with stacked material layers, utilizing a resonator structure between electrodes for predetermined band extraction and total reflection at partition wall interfaces to manage light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflector structure is used to increase light extraction efficiency, then light extraction efficiency is improved, but color balance becomes difficult to achieve due to variations in light emission characteristics
Solution Approach 1:
The patent divides the light extraction function into two distinct segments: a resonator structure for extracting light in a predetermined wavelength band and partition walls for extracting light in other bands through total internal reflection. This segmentation allows each component to be optimized for its specific function, resolving the contradiction between light extraction efficiency and color balance.
Solution Approach 2:
The patent applies different optical properties to different parts of the device: the resonator structure has properties optimized for resonant coupling at specific wavelengths, while the partition walls have properties optimized for total internal reflection at other wavelengths. This local differentiation enables simultaneous optimization of light extraction efficiency and color balance.
2Manufacturing precision
If multiple light emitting layers are stacked to achieve color balance, then color balance is improved, but light emission characteristics vary depending on coating properties making independent control difficult
Solution Approach 1:
The resonator structure acts as an intermediary element that selectively enhances specific wavelength bands through resonant coupling, while the partition walls serve as intermediaries for extracting other wavelength bands through total internal reflection. This intermediary approach simplifies the control of light emission characteristics by decoupling the functions of different wavelength extraction.
3Manufacturing precision
If white light is color-separated by color filter, then color display is achieved, but light emission efficiency decreases
Solution Approach 1:
Instead of using a color filter to separate white light into spectral components (which absorbs light and reduces efficiency), the patent extracts specific wavelength bands directly from the light emitting layers using the resonator structure and partition walls. This extraction approach maintains higher light emission efficiency while achieving color display functionality.
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 design enables easy color balance and improved light extraction efficiency by selectively extracting light through resonator and total reflection mechanisms, enhancing display performance.
Implementation Method 1
light in a predetermined band is extracted to the outside by a resonator structure formed between the lower electrode and the upper electrode
Implementation Method 2
light in a band different from the predetermined band is extracted to the outside by total reflection at an interface between the organic layer and the partition wall
Data Source
AI summary
Display devices and electronic devices are disclosed. In one example, a display device includes lower electrodes arrayed in a matrix on a substrate; partition walls between adjacent ones of the lower electrodes; an organic layer formed by stacking material layers on an entire surface including upper surfaces of the lower electrodes and upper surfaces of the partition walls; and an upper electrode formed on an entire surface including an upper surface of the organic layer. In pixels with a light emitting unit in which the lower electrodes, the organic layer, and the upper electrode are stacked, light in a predetermined band is extracted to the outside by a resonator structure formed between the lower electrode and the upper electrode, and light in a band different from the predetermined band is extracted to the outside by total reflection at an interface between the organic layer and the partition wall.