AMOLED Common Semiconductor Layers to Reduce Pixel Cross Talk
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Solution Overview
Problem
Active-matrix OLED displays suffer from cross talk between neighbor pixels due to the high electrical conductivity of shared hole transport layers, which affects display performance.
Innovation Solution
Implementing a common semiconductor layer structure with specific organic p-dopants in the OLED pixels, including a common hole injection layer and electron blocking layer, to maintain low sheet resistance and reduce cross talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common hole transport layer is used across multiple OLED pixels, then device complexity is reduced and manufacturing is simplified, but electrical cross talk between adjacent pixels increases due to high electrical conductivity
Solution Approach 1:
The common hole transport layer is segmented into multiple sub-layers: a first common hole transport layer extending over at least two pixels, and a second common hole transport layer extending over at least three pixels. This spatial segmentation reduces electrical cross talk by creating intermediate regions that limit charge carrier leakage between adjacent pixels while maintaining the overall common structure benefit.
Solution Approach 2:
Different regions of the hole transport layer are assigned different properties through the sub-layer structure. The first and second common hole transport layers have different extension patterns across the pixel array, creating local variations in electrical conductivity and charge carrier distribution that prevent cross talk while maintaining efficient hole transport where needed.
2Ease of operation
If organic p-dopants are used in the hole transport layer to enhance hole injection, then hole injection efficiency improves, but free charge carrier concentration increases which may worsen cross talk
Solution Approach 1:
The concentration and distribution of organic p-dopants are carefully controlled and optimized in the common hole transport layer. By adjusting dopant parameters (concentration, spatial distribution, and temporal characteristics), the system achieves sufficient hole injection efficiency while preventing excessive free charge carrier concentration that would cause cross talk between pixels.
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
The solution effectively minimizes electrical cross talk between pixels, enhancing the display's performance by maintaining high operational stability and reducing color mixing, while using organic p-dopants to enhance hole injection without increasing free charge carrier concentration.
Implementation Method 1
the common first semiconductor layer comprises at least one organic p-dopant
Implementation Method 2
light is produced and emitted by the light-emitting diode through the injection of charge carriers (electrons from one side, holes from another side) from the contacts into adjacent organic layers as a result of an externally applied voltage, subsequent formation of excitons (electron-hole pairs) in an active zone, and radiative recombination of these excitons
Data Source
Figure 1
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AI summary
The present invention relates to an active-matrix OLED display, comprising a plurality of OLED pixels, wherein each pixel itself comprises a stack of organic layers and each layer of the stack of organic layers can form a common semiconductor layer, wherein - at least a first OLED pixel and a second OLED pixel comprising - an anode layer, - a common cathode layer, - at least one emission layer, which is optional a common emission layer, - at least a stack of organic layers.