Organic EL Display Electrode Structure for Reflection Reduction
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Solution Overview
Problem
Organic EL display devices face challenges in reducing external light reflection while maintaining light emission efficiency, as conventional solutions like circular polarizing plates compromise thinness and light emission efficiency.
Innovation Solution
The use of a specific electrode structure comprising a first transparent electrode, a second metal electrode with lower transmittance and higher reflectance, and a third reflective electrode across adjacent pixels, optimized in thickness and material composition to minimize external light reflection without sacrificing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circular polarizing plate is disposed on the display surface side to reduce external light reflection, then external light reflection is reduced, but the device thickness increases and light emission efficiency is uniformly reduced across all wavelengths
Solution Approach 1:
The invention divides the reflective layer into multiple segments: a first reflective layer (second electrode) positioned closer to the organic light emitting diode, and a second reflective layer (third electrode) positioned farther away. This segmentation creates a multi-layer interference structure that reduces external light reflection through destructive interference, while maintaining device thinness and avoiding uniform reduction of light emission efficiency across all wavelengths
Solution Approach 2:
The invention applies different optical properties to different layers: the first reflective layer has specific reflectivity and transmittance characteristics optimized for light emission, while the second reflective layer is optimized for reducing external light reflection. The insulating layer between them has specific thickness and refractive index properties to control interference effects, creating localized optical quality improvements without compromising overall performance
2Object-affected harmful factors
If new layers are laminated for each pixel to reduce reflected light, then external light reflection is reduced, but the openings must be narrowly designed considering position deviation, which lowers light emission efficiency
Solution Approach 1:
The invention merges the function of reducing external light reflection with the existing electrode structure by making the second and third electrodes serve dual purposes: as electrical electrodes for the organic light emitting diode and as optical interference layers for reducing external light reflection. This eliminates the need for separate additional layers, allowing openings to be designed without excessive narrowing while achieving both reflection reduction and maintaining light emission 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
This configuration effectively reduces external light reflection across a wide wavelength range while maintaining or improving light emission efficiency, achieving a thinner and more cost-effective display device.
Implementation Method 1
an electrode arranged on a back side as seen from a display surface side of electrodes for supplying a current to an organic layer may be made of a material high in reflectivity
Implementation Method 2
the invention for obtaining a reduction effect in the external light reflection due to a laminated body of a semi-reflective layer, a transparent layer, and a reflective layer
Data Source
AI summary
A display device includes: an organic layer arranged in plural pixels which are arranged in a display area in a matrix; a first electrode that is formed on a surface of the organic layer opposite to a substrate, and transmits a visible light; a second electrode that holds the organic layer in cooperation with the first electrode, and is lower in the transmittance of the visible light, and higher in the reflectance than the first electrode; an insulating layer that holds the second electrode in cooperation with the organic layer, and higher in the transmittance of the visible light, and lower in the reflectance than the second electrode; and a third electrode that holds the insulating layer in cooperation with the second electrode, is formed across adjacent pixels of the plural pixels, and lower in the transmittance of the visible light, and higher in the reflectance than the second electrode.