Organic EL Device Dual Structure Light Extraction
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Solution Overview
Problem
Conventional organic electroluminescence (EL) devices face challenges in simultaneously enhancing light utilization efficiency and color purity, with existing solutions either improving one aspect at the expense of the other, due to limitations in light extraction and micro-cavity effects.
Innovation Solution
The organic EL device incorporates a dual structure section design, featuring a recessed first structure section with a reflection layer and a micro-cavity second structure section, where the first structure section enhances light extraction through refractive index matching and light scattering, and the second structure section achieves color purity through resonance effects, allowing for independent control of light extraction and micro-cavity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a micro-cavity structure is used to enhance color purity, then color purity is improved, but light utilization efficiency deteriorates
Solution Approach 1:
The light-emitting surface is divided into multiple regions with different structures: some regions have micro-cavity structures for high color purity, while other regions have flat or diffuser structures for high light extraction efficiency. This segmentation allows each region to optimize for its specific function while the overall device achieves both high color purity and high light utilization efficiency through the combined effect of multiple regions.
2Loss of energy
If light extraction is improved through refractive index matching, then light utilization efficiency is improved, but color purity deteriorates
Solution Approach 1:
The device is segmented into regions with different optical structures. Flat regions or regions with diffusers optimize light extraction efficiency by matching refractive indices and reducing total internal reflection. Micro-cavity regions optimize color purity through resonant enhancement. The combination of these segmented regions allows the device to achieve both high light extraction and high color purity simultaneously.
Solution Approach 2:
Different local regions of the light-emitting surface are given different optical properties: some regions are designed with micro-cavity structures that provide resonant enhancement and narrow emission spectra for high color purity, while other regions are designed with flat surfaces or diffusers that maximize light extraction efficiency. This local differentiation of optical quality allows simultaneous optimization of both parameters across the device.
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 results in an organic EL device that simultaneously achieves high light utilization efficiency and color purity, with adjustable effects by varying the area ratio of the structure sections, enabling optimal performance for specific applications.
Implementation Method 1
a light reflection layer which reflects light emitted from the organic EL element
Implementation Method 2
light emitted from the light-emitting layer is multiply reflected between a pair of reflection layers to resonance
Implementation Method 3
a recess including an inclined surface along an outer edge of the organic light-emitting layer is provided in the light reflection layer
Data Source
AI summary
An organic EL device according to the present invention includes: a first structure section; and a second structure section. The first structure section includes: a recess; a reflection layer provided along an inner surface of the recess; a filling layer filled at an inner side of the recess via the reflection layer; a first electrode; an organic layer including a light-emitting layer; and a second electrode. The second structure section includes: a reflection layer provided on a flat surface of the base material; a first electrode; an organic layer including a light-emitting layer; and a second electrode.