Organic Light Emitting Display Pixel Defining Layer Formation
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Solution Overview
Problem
Conventional methods for forming organic light emitting structures result in non-uniform organic layers on pixel defining layers, leading to leakage currents and irregular luminescence characteristics due to differences in material properties and thickness deviations near the sidewalls of the pixel defining layer.
Innovation Solution
A method involving the formation of a preliminary pixel defining layer with a photosensitive material, selectively exposed to create a hardened pixel defining layer and corresponding organic layer patterns, which reduces surface energy and modifies the properties of the underlying organic layers to minimize contact and crosstalk between adjacent pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If organic layers are formed on the sidewall of the pixel defining layer by printing or transfer process, then the organic layers can be formed in pixel regions, but the organic layers cannot be formed uniformly on the sidewall causing thickness deviation
Solution Approach 1:
The patent applies preliminary action by forming a preliminary pixel defining layer that includes a photosensitive material and a photoinitiator before forming the organic layers. This preliminary layer is selectively exposed to light to generate active species that diffuse into the organic layer material, modifying its properties in advance. This pre-modification ensures uniform formation of organic layers on sidewalls without requiring complex printing or transfer processes, thereby improving manufacturing precision while maintaining ease of operation.
Solution Approach 2:
The patent changes the physical and chemical parameters of the organic layer material through photopolymerization. The photoinitiator generates active species that diffuse into the organic layer material, causing polymerization that cross-links the material and modifies its solubility, adhesion, and electrical properties. This parameter change enables uniform coating of organic layers on sidewalls by controlling the molecular structure and intermolecular forces of the material, resolving the contradiction between manufacturing precision and operational ease.
2Area of stationary object
If organic layers with different materials contact the sidewall of the pixel defining layer, then coverage is achieved, but leakage current is generated near the sidewall
Solution Approach 1:
The patent applies local quality by creating spatially varying properties in the organic layer through selective photopolymerization. The preliminary pixel defining layer is selectively exposed to light in specific regions, generating active species that diffuse into and polymerize the organic layer material only in those regions. This creates local differences in cross-linking density, solubility, and electrical properties, allowing the organic layer to have different characteristics near the sidewall compared to other areas, thereby preventing leakage current while maintaining adequate coverage.
Solution Approach 2:
The patent introduces the preliminary pixel defining layer with photoinitiator as an intermediary between the pixel defining structure and the organic layer material. This intermediary generates active species that mediate the modification of the organic layer material through diffusion and polymerization. The intermediary enables controlled interaction between the pixel defining structure and organic layers, preventing direct contact that would cause leakage current while ensuring proper coverage through the mediating chemical reactions.
3Manufacturing precision
If the preliminary pixel defining layer is selectively exposed to light, then the pixel defining layer and organic layer pattern are transformed, but the process requires photoinitiator and light exposure equipment
Solution Approach 1:
The patent merges the pixel defining layer formation and organic layer patterning into a single photopolymerization process. The preliminary pixel defining layer contains both the structural definition and the photoinitiator, allowing simultaneous pattern transfer to both the pixel defining layer and the organic layer material through selective light exposure. This merging eliminates the need for separate printing or transfer equipment, reducing device complexity while maintaining high pattern formation precision through the integrated chemical process.
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 improved luminescence characteristics by preventing lateral diffusion of charges and confining hole transport or injection capabilities, thereby enhancing resolution and contrast in organic light emitting display devices.
Implementation Method 1
The first organic layer pattern may be formed by active species that are generated by the photoinitiator and diffused into the first organic layer. The first organic layer pattern may include a polymer cross-linked or polymerized by the active species.
Data Source
AI summary
In a method of forming an organic light emitting structure, a plurality of first electrodes spaced apart from each other is formed on a lower substrate. A first organic layer covering the first electrodes is formed on the lower substrate. A preliminary pixel defining layer is formed on the first organic layer. The preliminary pixel defining layer includes a photosensitive material, and is selectively exposed to light so that the preliminary pixel defining layer and a portion of the first organic layer beneath the preliminary pixel defining layer are transformed into a pixel defining layer and a first organic layer pattern, respectively. An emitting layer is formed on the first organic layer exposed by the pixel defining layer. A second organic layer is formed on the emitting layer. A second electrode is formed on the second organic layer.