Organic EL Display Charge Generation Layer Thickness Control
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Solution Overview
Problem
In organic EL display devices that use color filters to transmit light in specific wavelength ranges, color mixture occurs due to optical and electrical interactions between adjacent pixels, affecting chromaticity and image quality.
Innovation Solution
The device incorporates a TFT substrate with a charge generation layer of varying film thicknesses between light emission layers, and a color filter substrate with areas transmitting light in R, G, B, and W wavelength ranges, where the charge generation layer thickness is adjusted to minimize electrical color mixture by controlling electron flow between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a charge generation layer with uniform thickness is used, then the device structure is simple and manufacturing is easier, but electrical color mixture occurs between adjacent pixels affecting chromaticity
Solution Approach 1:
The charge generation layer is designed with different thicknesses in different regions corresponding to different wavelength ranges. Specifically, the first charge generation layer has a first thickness and the second charge generation layer has a second thickness different from the first, allowing localized control of charge generation to suppress electrical color mixture while maintaining manufacturing feasibility through a systematic layered structure.
2Manufacturing precision
If the charge generation layer thickness is increased to suppress electrical color mixture, then chromaticity precision improves, but device complexity increases
Solution Approach 1:
The charge generation layer is segmented into multiple distinct layers (first charge generation layer and second charge generation layer) with different thicknesses. This segmentation allows independent optimization of charge generation for different wavelength ranges without requiring a single complex variable-thickness layer, thereby improving chromaticity precision while managing device complexity through modular layering.
Solution Approach 2:
The thickness parameter of the charge generation layer is changed between different layers to optimize performance. The first charge generation layer has a first thickness and the second charge generation layer has a second thickness, allowing parameter variation to suppress electrical color mixture and improve chromaticity precision without requiring continuous or complex thickness modulation within a single layer.
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 suppresses the influence of electrical color mixture on chromaticity, enhancing image quality and current efficiency while allowing controlled luminance compensation between pixels.
Implementation Method 1
a charge generation layer which is arranged between the at least two light emission layers, is a layer to generate a pair of positive and negative charges
Implementation Method 2
at least two light emission layers that are arranged between the pair of electrodes
Data Source
AI summary
An organic EL display device includes: a TFT substrate that includes a display area in which pixels are arranged in a matrix; and a color filter substrate that is provided to face the TFT substrate and includes an area transmitting light in a predetermined wavelength range for each of the pixels. Each of the pixels of the TFT substrate includes a pair of electrodes, at least two light emission layers that are arranged between the pair of electrodes, and a charge generation layer that is arranged between the at least two light emission layers, is a layer to generate a pair of positive and negative charges, and has different film thicknesses in accordance with the predetermined wavelength range of the corresponding area.