Inkjet Conductive Polymer Layer for OLED Pixel Defect Reduction
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Solution Overview
Problem
Passive matrix type OLEDs suffer from rapid power consumption increases with larger display areas and higher resolution, leading to pixel defects due to incomplete coverage of organic layers on pixel electrodes during the manufacturing process.
Innovation Solution
A display device structure featuring a thin film transistor on an insulating substrate, with a conductive polymer layer formed by an inkjet method, alternating low molecular weight organic layers formed by thermal evaporation, and a polymer light emitting layer, which reduces pixel defects by ensuring uniform coverage and smooth hole and electron transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the wet method is used to form organic layers, then material consumption is reduced, but pixel defects occur due to incomplete coverage of pixel electrodes
Solution Approach 1:
The organic layer formation process is segmented into multiple sequential layers: a first organic layer formed by wet method, followed by a second organic layer formed by vacuum evaporation. This segmentation allows each layer to contribute different functions - the first layer provides material efficiency while the second layer ensures complete coverage and eliminates pixel defects
Solution Approach 2:
The patent employs a composite structure of organic layers combining materials deposited by different methods. The first organic layer (from wet method) and second organic layer (from vacuum evaporation) form a composite system that leverages the advantages of both deposition techniques to achieve both low material consumption and high reliability
2Ease of manufacture
If the wet method is used to form organic layers, then manufacturing cost is reduced, but coverage uniformity deteriorates
Solution Approach 1:
The organic layer structure is divided into two segments: a first organic layer formed by cost-effective wet method and a second organic layer formed by vacuum evaporation. This segmentation enables the bulk of the organic material to be deposited economically while a thinner compensating layer ensures uniform coverage
Solution Approach 2:
The second organic layer formed by vacuum evaporation provides localized quality improvement by ensuring uniform and complete coverage in critical areas where the wet method falls short, while the majority of the layer structure benefits from the cost-effective wet deposition
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 reduces pixel defects by alleviating surface unevenness of the first electrode and preventing direct contact between the electrode and light emitting layer, enhancing the display's reliability and performance.
Implementation Method 1
at least one of the conductive polymer layer and the polymer light emitting layer is formed by an inkjet method
Implementation Method 2
at least one of the first low molecular weight organic layer and the second low molecular weight organic layer is formed by a thermal evaporation method
Data Source
AI summary
A display device includes a thin film transistor formed on an insulating substrate; a first electrode electrically connected to the thin film transistor; a conductive polymer layer formed on the first electrode; a low molecular weight organic layer formed on the conductive polymer layer; a polymer light emitting layer formed on the low molecular weight organic layer; and a second electrode formed on the light emitting layer. With this configuration, a display device, which is capable of reducing pixel defects, can be provided.