OLED Display Pixel Structure for Viewing Angle Color Stability
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Solution Overview
Problem
OLED display devices face significant light loss and color shift issues due to the multi-layered thin film structure, particularly when white light emitted by multiple light-emitting layers is amplified through a microcavity structure, leading to color changes as the viewing angle varies.
Innovation Solution
The implementation of a substrate with specific pixel configurations, including a reflection layer, light-absorbing layer, and overlapping organic light-emitting layers, where the microcavity structure is applied only to certain pixels to prevent color distortion, and a semi-transparent layer is used in the pixel emitting white light to minimize reflection and enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a microcavity structure is applied to amplify white light emitted by multiple light-emitting layers, then light extraction efficiency is improved, but color stability deteriorates due to color change with viewing angle
Solution Approach 1:
The invention divides the display device into different pixel types: white pixels that utilize the microcavity structure for high light extraction efficiency, and color pixels that do not use the microcavity structure to maintain color stability. This segmentation allows each pixel type to be optimized for its specific function without compromise.
Solution Approach 2:
The microcavity structure is applied locally only to white pixels rather than uniformly across all pixels. This local application ensures that white pixels benefit from enhanced light extraction while color pixels maintain their color stability, as the microcavity structure is not applied to them.
2Power
If multiple light-emitting layers are used to emit white light, then light emission efficiency is improved, but color consistency deteriorates due to multiple peak wavelengths
Solution Approach 1:
The invention segments the pixel function by creating separate white pixels and color pixels. White pixels use multiple light-emitting layers for high emission efficiency, while color pixels use a single light-emitting layer for color consistency, avoiding the color shift problem inherent in multi-layer white emission.
3Adaptability or versatility
If a multi-layered thin film structure is used, then device functionality is improved, but light loss increases at layer interfaces
Solution Approach 1:
The invention introduces a semi-transparent electrode as an intermediary component in the microcavity structure. This semi-transparent electrode serves as a mediator that allows light to pass through while maintaining the electrical function, reducing light loss at the interface compared to fully opaque electrodes.
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 configuration effectively prevents color change with viewing angle and improves light extraction efficiency by optimizing the microcavity structure and layer thickness, resulting in enhanced color properties and extended OLED display device lifespan.
Implementation Method 1
the anode electrode 110 supplies a hole to the organic light-emitting layer 120, and the cathode electrode 130 supplies an electron to the organic light-emitting layer 120. Thus, when exciton, which is generated by the supplied hole and electron, falls to a ground state from an excited state, light is emitted
Implementation Method 2
a microcavity structure may be applied to the OLED display device. The microcavity structure indicates a reflection structure which satisfies an optical distance corresponding to an integer multiple of half-wavelength of the light emitted by each pixel. In this reflection structure, the light reflection is repeated so that the light is amplified by constructive interference
Implementation Method 3
the light reflection is repeated so that the light is amplified by constructive interference
Implementation Method 4
a cathode electrode formed of a semi-transparent metal material on the first organic light-emitting layer or second organic light-emitting layer
Data Source
AI summary
An OLED display device which prevents a color change according to a viewing angle. The OLED display device may include a substrate defined by a first pixel, a second pixel, a third pixel and a fourth pixel; an anode electrode on the substrate; a first organic light-emitting layer for emitting a first color light; a second organic light-emitting layer for emitting a second color light; a cathode electrode formed of a semi-transparent metal material on the first or second organic light-emitting layer, wherein the first organic light-emitting layer is formed in the first pixel and the second pixel; the second organic light-emitting layer is formed in the second pixel, the third pixel and the fourth pixel; and the second pixel emits mixed light of the first color light and the second color light.