Display Device White Subpixel Anode Thickness Optimization
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Solution Overview
Problem
Display devices with tandem organic light-emitting devices suffer from narrow viewing angles due to differing resonance characteristics of multiple emission layers, leading to color defects when the screen is tilted, necessitating an improvement in luminous efficiency and viewing angle performance.
Innovation Solution
A display device configuration featuring separate colored and white subpixels with distinct anode thicknesses and emission layer stacks, where the longer-wavelength emission stack is positioned adjacent to the cathode to enhance luminous efficiency, and a compensation pattern with controlled refractive index and extinction coefficient is used to mitigate viewing angle variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a tandem device with multiple emission layers is used, then luminous efficiency is improved, but viewing angle becomes narrow causing color defects
Solution Approach 1:
The device is divided into separate colored subpixels (red, green, blue) and white subpixels, each with dedicated emission layers. This segmentation allows each subpixel to be optimized independently, avoiding the viewing angle limitations that would affect a unified tandem structure with multiple emission layers.
Solution Approach 2:
Different anode thicknesses are applied to different subpixel types: colored subpixels have a first thickness while white subpixels have a second thickness. This local differentiation optimizes the optical characteristics and viewing angle for each subpixel type while maintaining high luminous efficiency.
2Loss of energy
If multiple emission layers with different resonance characteristics are stacked, then luminous efficiency increases, but color uniformity deteriorates at tilted viewing angles
Solution Approach 1:
The display is segmented into separate colored and white subpixels rather than using a single multi-layer tandem structure. Each subpixel type has its own optimized emission layers, preventing the color uniformity deterioration that occurs when multiple emission layers with different resonance characteristics are stacked in a conventional tandem configuration.
Solution Approach 2:
Different anode thicknesses are used for colored versus white subpixels to locally optimize the optical path and resonance characteristics for each subpixel type, maintaining color uniformity across different viewing angles while preserving luminous efficiency.
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 significantly increases luminous efficiency and reduces color variation across viewing angles, improving the display's overall performance without altering existing materials or dopants, thereby enhancing both luminance and color gamut characteristics.
Implementation Method 1
a first stack having a first blue emission layer, a second stack having a second blue emission layer, and a third stack having at least one of emission layers having a longer wavelength than the blue emission layers
Implementation Method 2
a compensation pattern provided between the second anode and the substrate
Implementation Method 3
a compensation pattern with controlled refractive index and extinction coefficient
Data Source
AI summary
A display device, includes a substrate having at least two colored subpixels and a white subpixel separately arranged thereon; a first anode having a first thickness at each of the colored subpixels on the substrate; a second anode, having a thickness smaller than the first thickness, at the white subpixel on the substrate; an organic stack comprising a first stack having a first blue emission layer, a second stack having a second blue emission layer, and a third stack having at least one of emission layers having a longer wavelength than the blue emission layers, which are provided in sequence on the first anode in the colored subpixel and the second anode in the white subpixel; a cathode over the organic stack; and a compensation pattern between the second anode and the substrate.