OLED Step Electrode Structure for Luminance Uniformity
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Solution Overview
Problem
Organic light emitting display devices face challenges in maintaining high display luminance and luminance uniformity, leading to irregular color shift and white angular dependency (WAD) characteristics when viewed from different angles, affecting user visibility.
Innovation Solution
The implementation of a step structure in the light-emitting area of the display device, where the second via insulation layer and first electrode have varying heights between the inner and outer light-emitting areas, with the second conductive member providing driving voltage and overlapping the outer light-emitting area and peripheral area, to ensure uniform light emission and reduced voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple conductive patterns are added to maintain high driving voltage supply, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The display area is divided into inner light-emitting area and outer light-emitting area with different electrode heights, segmenting the lighting function by spatial zone to achieve uniform luminance across different viewing angles
Solution Approach 2:
The first electrode is configured with varying heights in different regions (inner and outer light-emitting areas), adding a vertical dimension to the electrode structure to control light emission angles and improve luminance uniformity
2Adaptability or versatility
If step structure is implemented with varying electrode heights, then viewing angle uniformity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The electrode structure is segmented into multiple height levels corresponding to inner and outer light-emitting areas, allowing independent optimization of each region for different viewing angles
Solution Approach 2:
Different regions of the first electrode are given different heights and properties - the inner light-emitting area has one height while the outer light-emitting area has another height, optimizing each region for its specific function
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 improves the uniformity of light emission angles and reduces color shift, enhancing user visibility by maintaining consistent luminance and color appearance across different viewing angles.
Implementation Method 1
An electron injected from the cathode and a hole injected from the anode area may be combined to generate an exciton, and the exciton emits light while emitting energy
Data Source
AI summary
An organic light emitting display device includes a thin film transistor on a substrate including a display area having an inner light-emitting area and an outer light-emitting area and a peripheral area, a first conductive member connected to the thin film transistor, a first via insulation layer covering the first conductive member, a second conductive member on the first via insulation layer to overlap the outer light-emitting area and a part of the peripheral area, a second via insulation layer covering the second conductive member, a first electrode on the second via insulation layer to overlap the display area and a part of the peripheral area, an organic light emitting layer on the first electrode, and a second electrode on the organic light emitting layer. The second via insulation layer and the first electrode have a step structure between the inner and outer light-emitting areas.