Composite Hole Injection Layer for OLED Dark Spot Reduction
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Solution Overview
Problem
The existing methods for manufacturing organic light-emitting display devices suffer from dark spots caused by foreign matter on the first electrode, leading to poor surface states between layers, unbalanced hole injection, increased resistance, and higher power consumption due to heat treatment of the hole injection layer.
Innovation Solution
A method involving a mixture layer composed of two or more organic materials with different glass transition points, where the mixture layer is heated above the lowest and below the highest Tg to cover foreign matter without degrading, ensuring efficient hole injection and maintaining low resistance between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hole injection layer is heated at a temperature equal to or higher than its glass transition point to cover foreign matter, then dark spots are reduced, but the hole injection layer deteriorates causing poor surface state and reduced hole injection efficiency
Solution Approach 1:
The patent uses a composite hole injection layer comprising multiple organic materials with different glass transition points. This composite structure allows the layer to be heated above the Tg of individual components to cover foreign matter, while the combined materials maintain stable properties and good surface state that single materials cannot achieve alone.
Solution Approach 2:
The patent changes the physical parameters of the hole injection layer by selecting materials with specific glass transition points and combining them in particular ratios. This parameter optimization enables the layer to undergo controlled flow at heating temperatures while maintaining structural integrity and surface quality after cooling.
2Reliability
If the hole injection layer is heated to cover foreign matter, then dark spots are reduced, but resistance between electrodes increases leading to higher power consumption
Solution Approach 1:
The composite hole injection layer with multiple organic materials provides both the flowability needed to cover foreign matter and the electrical conductivity needed to maintain low resistance. The synergistic combination of materials achieves both dark spot reduction and low power consumption simultaneously.
3Device complexity
If a single organic material is used in the hole injection layer, then the structure is simple, but it cannot be heated sufficiently to cover foreign matter without degrading
Solution Approach 1:
The patent transitions from a simple single-material structure to a composite multi-material structure. This composite approach provides the necessary thermal response to cover foreign matter while maintaining overall structural simplicity in terms of layer configuration and manufacturing 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 effectively reduces dark spots, maintains balanced hole injection, and prevents increases in driving voltage, resulting in high-yield, long-lived, and low-power consumption display devices.
Implementation Method 1
heating the mixture layer at a temperature higher and lower than respectively the lowest and highest of the glass transition points of the organic materials
Implementation Method 2
heating the mixture layer... thereby providing a organic layer having at least the mixture layer and the light-emitting layer
Data Source
AI summary
A method for manufacturing a display device with an organic light-emitting element includes the steps of providing a first electrode on a substrate, providing on the first electrode a mixture layer having two or more organic materials differing in glass transition point, heating the mixture layer at a temperature higher and lower than respectively the lowest and highest of the glass transition points of the organic materials, providing a light-emitting layer on the mixture layer, thereby providing a organic layer having at least the mixture layer and the light-emitting layer, and finally providing a second electrode on the organic layer.