Tandem Light-Emitting Element Resonance Layout for Wide Viewing Angles
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Solution Overview
Problem
The luminance of existing light-emitting elements decreases significantly when the viewing angle deviates from the front view, resulting in poor viewing angle properties.
Innovation Solution
A light-emitting element design featuring a lower electrode that reflects light and an upper electrode that transmits and reflects light, with a first viewing angle for maximum resonance effect for the lower light-emitting layer differing from a second viewing angle for the upper light-emitting layer, optimized by adjusting distances and refractive indices to enhance resonance effects at different angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a tandem organic EL element structure is used to achieve high luminous efficiency, then luminous efficiency is improved, but viewing angle properties deteriorate (luminance decreases significantly when viewing angle moves away from 0°)
Solution Approach 1:
The patent divides the light-emitting element into two separate light-emitting layers (first and second light-emitting layers) positioned at different distances from the lower electrode. This segmentation allows each layer to be optimized for different viewing angles, with the first layer contributing to front-view luminance and the second layer contributing to off-angle luminance, thereby resolving the contradiction between high luminous efficiency and good viewing angle properties
Solution Approach 2:
The patent applies different local qualities to different parts of the light-emitting element by setting different cavity resonance conditions for the first and second light-emitting layers. The first light-emitting layer is positioned to achieve maximum resonance at a first cavity thickness for front-view observation, while the second light-emitting layer is positioned to achieve maximum resonance at a different cavity thickness for off-angle observation. This local optimization of resonance conditions improves viewing angle properties while maintaining high luminous efficiency
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
Improves luminance and color purity by optimizing resonance conditions for each light-emitting layer, enhancing viewing angle properties and maintaining high luminance across various angles.
Implementation Method 1
a lower electrode that reflects light
Implementation Method 2
a first viewing angle at which light emitted by the lower light-emitting layer with a selected wavelength achieves a maximum resonance effect
Implementation Method 3
an upper electrode that transmits and reflects light
Implementation Method 4
an upper electrode that transmits and reflects light
Implementation Method 5
light emitted by the lower light-emitting layer with a selected wavelength
Implementation Method 6
a first viewing angle at which light emitted by the lower light-emitting layer with a selected wavelength achieves a maximum resonance effect
Data Source
AI summary
A light-emitting element includes: a lower electrode that reflects light; an upper electrode that transmits and reflects light; and a lower light-emitting layer and an upper light-emitting layer both between the lower electrode and the upper electrode, wherein a first viewing angle at which light emitted by the lower light-emitting layer with a selected wavelength achieves a maximum resonance effect differs from a second viewing angle at which light emitted by the upper light-emitting layer with the selected wavelength achieves a maximum resonance effect.