OLED Microcavity Light Extraction via Gradient Refractive Index
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Solution Overview
Problem
Existing OLEDs with microcavity structures typically have maximum light distribution in the central direction, limiting the ability to achieve higher luminous intensity in directions different from the center direction.
Innovation Solution
A light-emitting device with a microcavity structure comprising a reflecting layer, a semi-transparent reflecting layer, and an organic layer, where the light distribution has a higher luminous intensity in a direction different from the reference direction, achieved by optimizing the thickness of layers and phase shift amounts to satisfy specific optical path differences and interference conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity structure is used in OLED, then light extraction efficiency is improved, but light distribution is concentrated in the center direction only
Solution Approach 1:
The patent introduces a gradient refractive index layer between the microcavity structure and the external environment. This layer has refractive index that varies continuously from the microcavity side to the external side, creating different optical properties in different regions. This gradient structure enables light to be extracted in multiple directions while maintaining high extraction efficiency, resolving the contradiction between concentrated light extraction and multi-directional light distribution.
Solution Approach 2:
The patent changes the refractive index parameter spatially by introducing a gradient refractive index layer. The refractive index varies continuously through the layer thickness, transforming the optical characteristics from uniform to gradient. This parameter change enables light to propagate in multiple directions with different intensities, achieving both high extraction efficiency and versatile light distribution patterns.
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 light-emitting device achieves a higher luminous intensity in desired directions, enhancing the light distribution pattern and contrast, while maintaining the desired chromaticity and spectral distribution.
Implementation Method 1
an organic layer between the reflecting layer and the semi-transparent layer, the organic layer including a light-emitting layer
Implementation Method 2
The light from the organic layer is reflected between the reflecting layer and the semi-transparent reflecting layer and emitted from the semi-transparent reflecting layer side
Implementation Method 3
a reflecting layer, a semi-transparent reflecting layer
Data Source
AI summary
A light distribution of light from a light-emitting device (10) has a higher luminous intensity in a first direction (D1) compared to a reference direction (R), the first direction (D1) being different from the reference direction (R). The reference direction (R) is a center direction of the light distribution, for example, a direction along the thickness direction of a substrate (100), a direction along the width direction of each layer (for example, an EML (126)) of a resonator (150), or a normal direction of a second surface (104) of the substrate (100). In addition, the light distribution has a higher luminous intensity in a second direction (D2) compared to the reference direction (R), the second direction (D2) being on an opposite side of the first direction (D1) with respect to the reference direction (R).