Top-Emitting OLED Light-Scattering Layer for Photon Extraction
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Solution Overview
Problem
OLED devices suffer from inefficiency in light extraction due to internal reflection, with up to 80% of generated photons being trapped, and existing solutions like diffraction gratings and scattering layers either fail to extract all light or cause color shifts and reduced sharpness in displays.
Innovation Solution
A top-emitting OLED device design featuring a light-scattering layer over the organic material, a transparent cover with color filters and a color-conversion material layer positioned between the cover and substrate, and a low-index gap between the scattering layer and color filters, optimizing light extraction and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a light-scattering layer is added to extract trapped light, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the light-scattering layer with the color-conversion material layer into a single integrated layer. This merging of functions reduces the total number of layers and simplifies the device structure while maintaining both light extraction and color conversion capabilities, thereby improving light extraction efficiency without proportionally increasing device complexity
Solution Approach 2:
The integrated layer serves multiple functions simultaneously: it acts as both a light-scattering layer for extracting trapped photons and a color-conversion layer for converting blue light to red light. This multi-functionality reduces the number of separate components needed, addressing the contradiction between improving light extraction and maintaining device simplicity
2Device complexity
If color filters are placed close to the OLED for compact design, then device complexity is reduced, but light extraction efficiency decreases due to increased absorption
Solution Approach 1:
The light-scattering layer acts as an intermediary between the OLED and the color filters. It scatters trapped light back toward the interface, increasing the probability of extraction before the light reaches the color filters. This intermediary function reduces absorption losses in the color filters while maintaining a compact device structure with fewer layers
3Loss of energy
If multiple separate layers are used for light scattering and color conversion, then functional performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the light-scattering function and color-conversion function into a single integrated layer, reducing the number of deposition steps and alignment procedures required during manufacturing. This single-layer approach simplifies the manufacturing process while maintaining the optical performance benefits of both functions
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 design enhances light output by scattering trapped photons, improving efficiency and reducing manufacturing complexity and costs while maintaining color accuracy and sharpness in OLED displays.
Implementation Method 1
a light-scattering layer formed over the one or more OLEDs for scattering light emitted by the one or more layers of light-emitting organic material
Implementation Method 2
The color-conversion materials absorb the high-frequency light and re-emit light at lower frequencies
Implementation Method 3
The color filters may be combined with color-conversion materials to further improve the color of the emitted light and to absorb incident light and avoid exciting the color-conversion materials with ambient light
Data Source
AI summary
A top-emitting OLED device, comprising: one or more OLEDs formed on a substrate; a light-scattering layer formed over the one or more OLEDs; a transparent cover; one or more color filters formed on the transparent cover; a color-conversion material layer formed over the color filters, or formed over or integral with the light-scattering layer; wherein the substrate is aligned and affixed to the transparent cover so that the locations of the color filters and color conversion material correspond to the location of the OLEDs, and the color-conversion material layer, color filters, and the light-scattering layer are between the cover and substrate, and a low-index gap is formed between the light-scattering layer and the color filters, with no light-scattering layer being positioned between the color conversion material layer and the low-index gap.