OLED Inkjet Printing Confinement via Liquid Affinity Alteration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inkjet printing techniques for OLED display manufacturing face challenges in precision droplet deposition and uniformity, especially in high-resolution displays, leading to reduced fill factor and increased manufacturing costs due to droplet placement errors and film drying imperfections, which affect the efficiency and lifetime of OLED displays.
Innovation Solution
The method involves altering the liquid affinity properties of the first hole conducting layer to define emissive layer confinement regions, allowing for precise deposition of an organic light-emissive layer within these regions using inkjet printing, thereby improving droplet placement accuracy and reducing non-uniformities, and using larger confinement wells to accommodate conventional inkjet droplet sizes and printing system accuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional inkjet printing is used for OLED manufacturing, then manufacturing cost is reduced, but droplet placement precision deteriorates leading to material spillage and non-uniformity
Solution Approach 1:
The patent introduces a liquid crystal polymer (LCP) layer as an intermediary between the substrate and the OLED materials. This LCP layer acts as a mediator that provides precise patterning and confinement for the inkjet-deposited droplets, enabling conventional inkjet printers to achieve high precision material placement without requiring advanced printing systems
Solution Approach 2:
The LCP layer is formed and patterned before the OLED materials are deposited via inkjet printing. This preliminary action creates pre-defined confinement regions that guide and restrict the spread of subsequently deposited droplets, ensuring precise material placement even when using conventional inkjet technology with larger droplet sizes
2Measurement precision
If pixel density is increased for high resolution displays, then display quality is improved, but confinement well area is reduced making droplet containment difficult
Solution Approach 1:
The LCP layer is selectively patterned to create local confinement regions with different properties in different areas. Each confinement region is locally optimized to contain droplets within specific sub-pixel areas while maintaining the overall high pixel density layout, allowing precise material placement even in high-resolution displays with small confinement well areas
Solution Approach 2:
The LCP layer forms a thin film structure that provides flexible confinement boundaries. This thin film approach allows the creation of numerous small confinement regions for high pixel density while maintaining sufficient area within each region to accommodate conventional inkjet droplet sizes without spillage into adjacent sub-pixels
3Manufacturing precision
If droplet volume is reduced to fit confinement wells, then material containment is improved, but deposition reliability deteriorates due to system precision limitations
Solution Approach 1:
The patent converts the potentially harmful effect of large droplet volumes (which would cause spillage) into a benefit by using the LCP confinement regions to contain and direct the droplets. The larger droplet volumes that would normally be problematic are now advantageous as they ensure complete coverage of the confinement region and robust material deposition, while the LCP layer prevents any spillage into adjacent areas
Solution Approach 2:
The LCP confinement regions serve as a protective cushion or barrier before droplet deposition. This pre-established confinement structure absorbs and contains any potential droplet spread or placement errors, cushioning against deposition failures and ensuring reliable material containment within the intended sub-pixel areas
4Measurement precision
If confinement well area is reduced for high resolution, then pixel density is improved, but film drying imperfections increase affecting layer uniformity
Solution Approach 1:
The LCP layer is segmented into distinct confinement regions corresponding to individual sub-pixels. This segmentation isolates the drying process within each small confinement region, allowing uniform solvent evaporation and film formation in each segment. The segmentation prevents drying imperfections from propagating across the entire display area and ensures consistent layer uniformity even in high-resolution displays with numerous small confinement regions
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 approach enhances the reliability of active OLED layer deposition, increases the fill factor, and improves the uniformity and efficiency of OLED displays by maintaining droplet containment within confinement wells, leading to better light emission and extended pixel lifetime.
Implementation Method 1
A liquid affinity property of selected surface portions of the first hole conducting layer can be altered to define emissive layer confinement regions
Implementation Method 2
Inkjet printing uses droplets of ink containing OLED layer material and one or more carrier liquids ejected from a nozzle at a high speed
Data Source
AI summary
In accordance with an exemplary embodiment of the present disclosure, a method of manufacturing an organic light-emissive display can be provided. A plurality of electrodes can be provided on a substrate. A first hole conducting layer can be deposited via inkjet printing over the plurality of electrodes on the substrate. A liquid affinity property of selected surface portions of the first hole conducting layer can be altered to define emissive layer confinement regions. Each emissive layer confinement region can have a portion that respectively corresponds to each of the plurality of electrodes provided on the substrate. An organic light-emissive layer can be deposited via inkjet printing within each emissive layer confinement region.