OLED Pixel Defining Layer HALS Radical Scavenging
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Solution Overview
Problem
Organic electroluminescence display devices are susceptible to damage from external light, leading to reduced optical reliability and display quality due to the breakdown of chemical bonds in the pixel defining layer, resulting in radical formation and subsequent deterioration.
Innovation Solution
Incorporating a hindered amine light stabilizer (HALS) within the pixel defining layer, in combination with a base resin, to scavenge radicals formed by external light, thereby minimizing damage and maintaining display quality. The HALS is included in amounts ranging from 0.01 wt% to 5.0 wt% based on the total weight of the base resin, and may be accompanied by an ultraviolet ray absorbing agent for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pixel defining layer is made transparent to allow light emission, then display quality is improved, but the layer becomes vulnerable to external light damage causing radical formation and deterioration
Solution Approach 1:
A hindered amine light stabilizer (HALS) is introduced as an intermediary substance within the pixel defining layer. The HALS acts as a radical scavenger that intercepts and neutralizes radicals generated by external light exposure, preventing them from attacking the base resin. This mediator approach allows the layer to remain transparent for light emission while protecting against photo-degradation through the HALS's radical-trapping mechanism
Solution Approach 2:
The pixel defining layer is formulated as a composite material consisting of a base resin (such as polyimide, polyamide, or acrylic) combined with a hindered amine light stabilizer. This composite structure combines the optical properties of the base resin with the protective radical-scavenging capabilities of the HALS, creating a material that simultaneously achieves transparency for display quality and resistance to external light damage for optical reliability
2Reliability
If a large amount of hindered amine light stabilizer is added to the pixel defining layer, then protection against external light is improved, but side reactions may occur reducing display quality
Solution Approach 1:
The concentration of hindered amine light stabilizer in the pixel defining layer is precisely controlled within the range of 0.01 wt% to 5.0 wt% based on the total weight of the base resin. This parameter optimization ensures sufficient radical-scavenging capability for protection against external light while maintaining the transparency and optical properties necessary for display quality. The specific concentration range balances protective function with optical performance
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
The use of hindered amine light stabilizers effectively captures radicals generated by external light, preventing deterioration of the pixel defining layer and enhancing the optical reliability and display quality of organic electroluminescence display devices, while optimizing the amount of HALS to avoid side reactions.
Implementation Method 1
the pixel defining layer includes a base resin and a hindered amine light stabilizer (HALS)... the hindered amine light stabilizer may include at least one of a first compound having a structure represented by formula 1 below in a molecule and a second compound having a structure represented by formula 2 below in a molecule
Implementation Method 2
the pixel defining layer further includes an ultraviolet ray absorbing agent
Data Source
AI summary
Provided is an organic electroluminescence display device including a substrate, a first electrode disposed on the substrate, a pixel defining layer disposed on the first electrode and having an opening defined therein for exposing at least a part of the first electrode, an organic layer disposed on the first electrode exposed by the opening and including a light emitting layer, and a second electrode disposed on the organic layer, wherein the pixel defining layer includes a base resin and a hindered amine light stabilizer (HALS).