Transparent OLED Microcavity Light Efficiency
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Solution Overview
Problem
Transparent organic light emitting diode displays face a trade-off between increased transmittance and reduced light emission efficiency, as widening the see-through region to enhance transmittance often results in decreased light emission efficiency.
Innovation Solution
Incorporating a structure with multiple selective reflection layers containing cholesteric liquid crystals, which are strategically positioned between transparent electrodes and an organic emissive layer to selectively reflect blue, green, and red color lights, and are spaced apart to generate microcavity effects, thereby enhancing light emission efficiency while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the see-through region is widened to increase transmittance, then transmittance is improved, but light emission efficiency is lowered
Solution Approach 1:
The patent segments the display into multiple functional regions: see-through regions for transparency and emission regions with organic light emitting diodes for light emission. This segmentation allows each region to optimize its specific function without compromising the other, resolving the contradiction between transmittance and light emission efficiency
Solution Approach 2:
Different regions of the display are assigned different optical properties: see-through regions have high transmittance while emission regions have high light emission efficiency. The selective reflection layers are strategically positioned to reflect specific wavelengths in different regions, creating local quality variations that simultaneously achieve both high transmittance and high light emission efficiency
2Loss of energy
If selective reflection layers are added to improve light emission efficiency, then light emission efficiency is improved, but device complexity increases
Solution Approach 1:
The selective reflection layers serve multiple functions simultaneously: they reflect specific wavelengths to improve light emission efficiency, enable color separation for full-color display, and maintain transparency in see-through regions. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity
Solution Approach 2:
Selective reflection layers act as intermediary components between the organic light emitting diodes and the external environment. These layers mediate the interaction between emitted light and external light, enabling wavelength-selective reflection without requiring complex optical systems, thus improving light emission efficiency while controlling device complexity
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 improves light emission efficiency and image quality by ensuring that light emitted from the organic light emitting diode is not overlapped with external light, allowing for increased transparency and recognition of objects behind the display.
Implementation Method 1
a first selective reflection layer disposed to receive light from the organic emissive layer
Implementation Method 2
At least one of the first to third selective reflection layers may contain a cholesteric liquid crystal
Implementation Method 3
the first sub-emission layer may be spaced apart from the first selective reflection layer by a first length, the second sub-emission layer may be spaced apart from the first selective reflection layer by a second length that is greater than the first length
Data Source
AI summary
An organic light emitting diode display includes a first electrode and a second electrode, an organic emissive layer disposed between the first electrode and the second electrode, a first selective reflection layer disposed to receive light from the organic emissive layer, and a third transparent electrode, the first selective reflection layer being between the third transparent electrode and the organic emissive layer.