Anti-reflection Optical Filter for Organic Light-emitting Device
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Solution Overview
Problem
Current optical filters for organic light-emitting devices suffer from strong viewing angle dependence, leading to deteriorated antireflection performance and visibility issues due to reflected external light, particularly on the sides of the display.
Innovation Solution
An optical filter comprising a linear polarizer and retardation films with specific optical axis orientations and thicknesses, including a first retardation film with a quarter-wave phase retardation characteristic and a second retardation film with splay-aligned liquid crystal molecules, which effectively control light polarization and phase delay to achieve omnidirectional antireflection and improved color characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-molecular-weight organic compound is used as the hole-transporting material, then the device can be manufactured with simple processes, but the compound aggregates at the interface with the aluminum electrode, causing poor hole extraction and reduced device lifetime
Solution Approach 1:
The patent uses a composite material system consisting of a low-molecular-weight hole-transporting material (HTM) combined with a specific aluminum complex compound. The aluminum complex acts as a host material that prevents aggregation of the HTM at the aluminum electrode interface while maintaining the manufacturing advantages of low-molecular-weight compounds. This composite approach allows simple vacuum deposition processes while achieving stable electroluminescence and extended device lifetime through improved charge extraction.
2Ease of manufacture
If conventional hole-transporting materials are used, then device manufacturing is straightforward, but light extraction efficiency is insufficient due to lack of effective light extraction structures
Solution Approach 1:
The patent employs an aluminum complex compound that exhibits specific optical properties and light emission characteristics. The aluminum complex layer emits light in a manner that enhances overall light extraction from the device, compensating for the lack of complex microstructured light extraction elements. This approach maintains manufacturing simplicity while improving light extraction efficiency through the optical properties of the aluminum complex material itself.
3Ease of manufacture
If simple vacuum deposition is used for manufacturing, then the process is simple and low-cost, but the lifetime of the organic light-emitting device is significantly reduced
Solution Approach 1:
The aluminum complex compound serves as an intermediary layer between the low-molecular-weight hole-transporting material and the aluminum electrode. This intermediary layer facilitates effective charge extraction and transfer while preventing direct contact and aggregation issues between the HTM and aluminum. The aluminum complex enables the use of simple vacuum deposition processes while achieving stable electroluminescence and extended device lifetime through its mediating function in charge transport and interface stabilization.
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 optical filter significantly reduces reflectance and enhances visibility by preventing external light reflection on both the front and sides of the organic light-emitting device, maintaining excellent antireflection performance across all directions.
Implementation Method 1
it has been confirmed that a key factor contributing to the poor extraction of holes from an organic layer to an aluminum electrode is the aggregation of a low-molecular-weight organic compound used as a hole-transporting material at the interface with the aluminum electrode
Implementation Method 2
When a specific aluminum complex compound is used as a hole-transporting material or a host for a luminescent dopant in an aluminum complex compound-containing organic light-emitting device, stable electroluminescence can be maintained for a long period of time
Implementation Method 3
An anti-reflection optical filter according to one embodiment of the present invention includes a first organic optical filter layer having a first refractive index and a first thickness, and a second organic optical filter layer having a second refractive index and a second thickness
Data Source
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AI summary
The present application relates to an optical filter and an organic light-emitting display device. The optical filter of the present application has excellent omnidirectional antireflection performance and color characteristics on the side as well as the front. The optical filter can be applied to an organic light-emitting device to improve visibility.