OLED Polyimide Substrate Treatment for High-Transmittance Camera Areas
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Solution Overview
Problem
The existing organic light emitting display devices using polyimide substrates face limitations in transmittance due to charge transfer complexes, leading to reduced visibility and increased material costs, especially when trying to minimize bezel areas by disposing components like cameras or sensors on the rear surface, as high-energy laser irradiation can damage the panel and leave residues.
Innovation Solution
A manufacturing method that treats the polyimide substrate with a ligand solution to inhibit charge transfer complex formation, improving transmittance without the need for high-energy laser irradiation, using a ligand compound that does not absorb visible light, thereby enhancing light transmittance and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyimide substrate is used for its heat resistance and mechanical strength, then the substrate maintains stability during high-temperature deposition, but light transmittance decreases due to charge transfer complex formation
Solution Approach 1:
The patent applies different treatments to different regions of the polyimide substrate. Specifically, the rear surface substrate in the display area is treated with a ligand solution to reduce charge transfer complex formation and improve transmittance, while other areas maintain the original polyimide properties for heat resistance and mechanical strength.
Solution Approach 2:
The patent introduces a ligand (such as oleic acid, oleylamine, or mercaptoacetic acid) as an intermediary substance that interacts with the polyimide chains. The ligand binds to the polyimide through coordination bonds, disrupting the charge transfer complex formation between amine and carbonyl groups, thereby improving light transmittance while maintaining the substrate's thermal and mechanical properties.
2Illumination intensity
If high-energy laser irradiation is used to remove polyimide in camera areas, then transmittance is improved, but the panel is damaged and reliability decreases
Solution Approach 1:
Instead of using high-energy laser irradiation that causes damage, the patent converts the problem by using a chemical ligand solution that gently disrupts charge transfer complexes. This approach achieves improved transmittance without the harmful effects of laser irradiation, such as panel damage, melting, or contamination.
Solution Approach 2:
The patent replaces the mechanical/physical method of laser irradiation with a chemical method using ligand solutions. The ligand chemically interacts with the polyimide to reduce charge transfer complex formation, achieving the same transmittance improvement goal without the damaging mechanical energy input of lasers.
3Illumination intensity
If transparent polyimide is used to improve transmittance, then light transmission is enhanced, but material cost increases significantly
Solution Approach 1:
The patent changes the chemical parameters of the polyimide substrate by introducing ligands that bind to the polyimide chains. This modification disrupts the charge transfer complex formation without requiring a complete change to transparent polyimide material, thereby achieving improved transmittance at a lower material cost.
Solution Approach 2:
The patent creates a composite structure where the polyimide substrate is combined with ligand molecules. This composite approach allows the use of cost-effective colored polyimide while the ligand component provides the transmittance improvement, avoiding the need to use expensive transparent polyimide throughout.
4Area of stationary object
If bezel area is reduced by disposing components on rear surface, then display area is increased, but transmittance requirements create manufacturing complexity
Solution Approach 1:
The patent divides the rear surface substrate into different functional regions: display areas where ligand treatment is applied to improve transmittance, and non-display areas (bezel regions) where the original polyimide structure is maintained. This segmentation allows selective treatment only where needed, simplifying the manufacturing process while achieving the desired display area expansion.
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 method selectively improves transmittance of the polyimide substrate, reducing bezel areas and maintaining display reliability with a low-cost material, while avoiding damage to the display panel, thus enabling a wider viewing area and cost-effective production.
Implementation Method 1
polyimide forms a charge transfer complex (CTC) by interactions within chains and between adjacent chains
Implementation Method 2
a ligand compound that does not absorb visible light, thereby enhancing light transmittance
Data Source
AI summary
An organic light emitting display device includes a first display area having a plurality of sub-pixel areas therein and a second display area having a plurality of sub-pixel areas and a plurality of transmissive areas therein. The organic light emitting display device includes a plastic substrate including a first portion corresponding to the first display area and a second portion corresponding to the second display area; a plurality of thin film transistors on the plastic substrate to correspond to the plurality of sub-pixel areas; and a plurality of organic light emitting elements on the plurality of thin film transistors to correspond to the plurality of sub-pixel areas, wherein the second portion includes polyimide and a ligand compound, and the first portion includes polyimide with the ligand compound absent therein.