OLED Well Undercut Shelf for Uniform Deposition
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Solution Overview
Problem
Current OLED fabrication techniques face challenges with solvent-based deposition methods, particularly in achieving uniform film thickness and preventing shorting due to pinning of organic electronic material at the edges of wells, especially in larger pixels, which affects the efficiency and reliability of the devices.
Innovation Solution
The proposed solution involves a substrate structure with a base layer, spacer layers, and a bank layer with an undercut shelf to create a recess for organic electronic material deposition, utilizing hydrophilic materials to pin the solvent and improve wetting, thereby reducing the risk of shorting and enhancing film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based deposition is used to deposit organic electronic material in wells, then the material can be deposited using solution processing methods, but the material pins at the edges of wells causing non-uniform film thickness and potential shorting
Solution Approach 1:
The patent applies preliminary action by pre-forming an undercut shelf structure at the base of the well before deposition. This shelf, created by depositing a spacer layer and then performing an isotropic etch to undercut it, is prepared in advance to receive and contain the solvent-based organic electronic material. The shelf's recess geometry is predetermined to prevent edge pinning during the subsequent deposition process, thus solving the uniformity issue while maintaining solution processing benefits.
2Device complexity
If the well edges are vertical, then the structure is simple to fabricate, but the organic electronic material pins at the edges causing shorting and non-uniform deposition
Solution Approach 1:
The patent applies asymmetry by creating an undercut shelf structure where the spacer layer extends beyond the bank layer at the base of the well. This asymmetric geometry, achieved through isotropic etching of the spacer layer, creates a recess that receives the organic electronic material and prevents it from pinning at the vertical edges. The asymmetric shelf profile maintains structural simplicity while effectively preventing shorting.
3Ease of manufacture
If the bank layer tapers uniformly, then the fabrication process is simple, but the solvent cannot be properly pinned at the well edges for uniform material distribution
Solution Approach 1:
The patent applies local quality by creating a specific undercut shelf geometry at the base of the well where the spacer layer extends beyond the bank layer. This localized structural modification, achieved through targeted isotropic etching, creates a recess with specific surface energy characteristics that enable proper solvent pinning. The local quality change at the shelf interface allows uniform material distribution while maintaining overall fabrication simplicity.
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 allows for improved wetting and uniform deposition of organic electronic materials, reducing the risk of shorting and enhancing the efficiency and reliability of OLED devices by decoupling the wetting attributes of PEDOT and LEP, and facilitating better surface energy management during the solvent-based deposition process.
Implementation Method 1
utilizing hydrophilic materials to pin the solvent and improve wetting
Implementation Method 2
isotropically etching said spacer layer to define an undercut shelf
Implementation Method 3
said bank layer being hydrophobic with respect to said solvent
Data Source
AI summary
An organic electronic device structure, the structure comprising: a substrate; a base layer supported by said substrate and defining the base of a well for solvent-based deposition of organic electronic material; one or more spacer layers formed over said base layer; a bank layer formed over said spacer layer to define a side of said well; and wherein an edge of said well adjacent said base layer is undercut to define a shelf over said base layer, said shelf defining a recess to receive said organic electronic material.