Bank Structures for Uniform Organic Electronic Device Emission
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Solution Overview
Problem
Existing methods for manufacturing organic electronic devices, such as OLEDs, face challenges in achieving uniform thickness of active layers within well-defined areas due to wetting effects and the need for complex machinery, which results in non-uniform emission and reduced light-emitting areas.
Innovation Solution
The use of bank structures with multiple electrode segments separated by thicker insulating layers, where the charge-transporting layer completely fills the well area, covering both electrode segments and insulating layers, to maintain uniform thickness and prevent short circuits, while being compatible with ink-jet printing and photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorinated materials are used in bank structures to control wettability and prevent spilling, then solution containment is improved, but manufacturing complexity increases due to additional material deposition steps
Solution Approach 1:
The patent changes the physical parameter of surface energy by using fluorinated materials with low surface energy to modify the wettability of bank structures. This allows the banks to be overfilled during inkjet printing while preventing spilling, as the solution naturally recedes from the low surface energy bank surfaces
Solution Approach 2:
The patent segments the bank structure into multiple functional layers: a base layer for mechanical support and a top fluorinated layer for wettability control. This segmentation allows each layer to perform its specific function independently, with the fluorinated layer being applied only where needed for solution containment
2Ease of manufacture
If conventional bank structures are used without insulating layers, then manufacturing is simpler, but non-uniform thickness of residual material occurs due to wetting effects near bank walls
Solution Approach 1:
The patent introduces an insulating layer as an intermediary between the conductive bank structure and the active material solution. This insulating layer acts as a mediator that prevents direct wetting interactions between the solution and bank walls, eliminating the capillary action that causes non-uniform thickness
Solution Approach 2:
The patent extracts the wetting function from the bank structure by removing the direct contact between the solution and the bank wall surface. The insulating layer is applied to the inner surface of the banks, effectively taking out the harmful wetting effect while preserving the bank's structural containment function
3Manufacturing precision
If insulating layers are added under bank structures to prevent wetting effects, then emission uniformity is improved, but aperture size of pixels is reduced
Solution Approach 1:
The patent applies the insulating layer locally only to the inner surfaces of the bank structures where solution containment is needed, rather than covering the entire pixel area. This localized application provides wetting control precisely where required while leaving the central active area fully available for light emission
Solution Approach 2:
The patent transitions from a two-dimensional planar insulating layer to a three-dimensional conformal coating that follows the inner contours of the bank structures. This allows the insulating layer to provide wetting control along the vertical walls of the banks without extending into the horizontal pixel aperture area
4Measurement precision
If photolithography is used to create bank structures, then patterning precision is improved, but compatibility with subsequent solution processing is reduced
Solution Approach 1:
The patent uses a composite material system consisting of a photoresist base layer for photolithographic patterning and a fluorinated polymer top layer for solution processing compatibility. The photoresist provides precise pattern definition during fabrication, while the fluorinated polymer provides the required low surface energy properties for subsequent inkjet printing and solution deposition steps
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 ensures uniform emission across active areas, minimizes loss of emission area due to wetting effects, and allows for cost-effective, high-output manufacturing of electronic devices with improved manufacturability.
Implementation Method 1
the thickness of the residual film is often critical in such devices but the solubility within an appropriate solvent is often limited, the amount of solution needed to be deposited within the cell may exceed the volume of the well and the solution could overspill into adjacent wells. One solution to this problem is to control the wettability of the top of the banks so that the contact angle is sufficiently high so that the well can be overfilled without spilling.
Implementation Method 2
One solution to this problem is to control the wettability of the top of the banks so that the contact angle is sufficiently high so that the well can be overfilled without spilling.
Data Source
AI summary
Electronic device and associated methods with multiple well areas located on a common substrate, where each well area is defined by at least three bank structures that form the side walls of the well area. Within each well area, there are at least two electrode segments where the electrode segments are separated laterally by at least one insulating bank where the insulating bank(s) are thicker than the electrode segments. There is at least one charge transporting layer completely filling the well area in direct contact and overlying both the electrode segments and the insulating bank(s). The well areas are filled using solution methods such as inkjet. Such devices have improved uniformity across the active areas.