OLED Second Electrode Segmentation for Light Extraction and Viewing Angle
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Solution Overview
Problem
OLED display devices face a trade-off between enhanced light extraction efficiency and viewing angle properties, where intense resonance structures improve light extraction but degrade color stability when viewed from different angles, affecting the reliability of the device.
Innovation Solution
A display device design featuring a second electrode with distinct transmission portions, where the second transmission portion has higher light transmittance than the first, surrounding the first transmission portion in the light emission area, to balance light extraction and viewing angle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a resonance structure is formed in each pixel to enhance light extraction efficiency, then light extraction efficiency is improved, but viewing angle properties are degraded due to intensified straightness of light propagation
Solution Approach 1:
The second electrode is divided into multiple transmission portions with different light transmittances (first transmission portion, second transmission portion, third transmission portion) arranged in different regions. This segmentation allows different parts of the electrode to serve different functions: enhancing light extraction in the center while maintaining viewing angle properties at the edges.
Solution Approach 2:
Different regions of the second electrode are assigned different light transmittance characteristics. The first transmission portion (center region) has lower light transmittance to enhance resonance and light extraction, while the second and third transmission portions (edge regions) have higher light transmittance to maintain viewing angle properties and reduce color shift.
2Illumination intensity
If a resonance structure with transflective and reflective electrodes is employed to generate constructive interference, then light extraction efficiency is significantly increased, but color shift depending on viewing angle is aggravated
Solution Approach 1:
The second electrode is segmented into multiple transmission portions with different light transmittances positioned in different regions. This segmentation enables the system to achieve both high light extraction efficiency (through the first transmission portion with lower transmittance) and color stability (through the second and third transmission portions with higher transmittance at the edges).
Solution Approach 2:
Different regions of the second electrode are assigned different light transmittance properties to simultaneously achieve high light extraction and color stability. The first transmission portion in the center region has lower light transmittance for enhanced light extraction, while the second and third transmission portions in the edge regions have higher light transmittance to maintain color stability across viewing angles.
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 design enhances light extraction efficiency while improving viewing angle properties, thereby increasing the reliability of the OLED display device by mitigating color shift issues.
Implementation Method 1
the second electrode includes a first transmission portion in the light emission area and a second transmission portion on an edge portion of the light emission area, the second transmission portion surrounding the first transmission portion, and the second transmission portion has a light transmittance greater than a light transmittance of the first transmission portion
Implementation Method 2
The resonance structure may include a transflective electrode as one of the anode and the cathode, which may display an image, and a reflective electrode as the other of the anode and the cathode to oppose thereto, which may generate constructive interference
Implementation Method 3
a reflective electrode as the other of the anode and the cathode to oppose thereto, which may generate constructive interference
Data Source
AI summary
A display device including a substrate including a light emission area and a non-light emission area, a pixel defining layer disposed in the non-light emission area, the pixel defining layer defining the light emission area, a first electrode disposed in the light emission area, a light emitting layer disposed on the first electrode, and a second electrode disposed on the light emitting layer, in which the second electrode includes a first metal layer and a second metal layer disposed on the first metal layer, and the second metal layer has an aperture disposed at an edge portion of the light emission area.