Organic Light-Emitting Device with Segmented Optical Paths
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Solution Overview
Problem
Organic light-emitting devices suffer from reduced color purity and impaired white balance when viewed at different angles due to changes in resonant wavelength and optical path, leading to variations in emission color and intensity.
Innovation Solution
The implementation of organic light-emitting devices with distinct optical paths in each pixel unit, where the resonant wavelengths are set to be identical, allowing for averaging of viewing angle characteristics and maintaining high color purity without enlarging the full width at half maximum of the emission spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical path is used in the light-emitting device, then the device structure is simple, but the viewing angle characteristics are poor and color purity decreases when viewed obliquely
Solution Approach 1:
The light-emitting device is divided into multiple pixel units (first pixel units and second pixel units) with different optical paths. Each pixel unit has its own resonator structure with specific optical path length, allowing the device to maintain color purity across different viewing angles by combining the emission characteristics of multiple segments with different optical responses.
Solution Approach 2:
Different pixel units are assigned different optical path characteristics locally. The first pixel units have one optical path length while the second pixel units have another optical path length, allowing each local region to contribute differently to the overall emission characteristics, thereby maintaining color purity when viewed from various angles.
2Illumination intensity
If the optical path is increased to enhance resonance, then the emission intensity at peak wavelength is improved, but the resonant wavelength shifts when viewing angle changes, causing color variation
Solution Approach 1:
The device uses multiple pixel units with different optical path lengths to segment the resonance enhancement function. By having both first pixel units and second pixel units with different optical characteristics, the device maintains emission intensity while compensating for viewing angle-induced wavelength shifts through the combined output of multiple segments.
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 approach enhances viewing angle characteristics while maintaining high color purity and emission efficiency, ensuring consistent color reproduction across various viewing angles.
Implementation Method 1
an optical path between a first reflective surface located on the first electrode side with respect to the emission layer and a second reflective surface located on the second electrode side with respect to the emission layer being set so as to resonate light emitted in the emission layer
Implementation Method 2
an optical interference effect is developed remarkably in which light with a particular wavelength is resonated to be enhanced in an organic light-emitting device
Data Source
AI summary
Provided are an organic light-emitting device that has wide viewing angle characteristics and enables excellent color reproduction, and a display apparatus including the organic light-emitting device. In the device, an optical path between a first reflective surface formed on the first electrode side with respect to an emission layer and a second reflective surface formed on a second electrode side with respect to the emission layer are set so as to resonate light emitted in the emission layer, and a first region with a relatively short optical path L1 and a second region with a relatively long optical path L2 are provided, wherein L1 and L2 are set to satisfy Expression 1 with resonant wavelengths λ1, λ2, and λ3, a sum φt of phase shifts when light is reflected by the first reflective surface and the second reflective surface, and a viewing angle α:λ1=2L1/(p−φt/2π)λ2=2L2/(q+1−φt/2π)λ3=2L2 cos α/(q−φt/2π)λ1=λ2=λ3 (Expression 1)wherein p and q each independently represent a positive integer and α is not 0°.