Organic Light-Emitting Device Fluoride Intermediate Layer
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Solution Overview
Problem
The use of an inorganic barrier layer between the organic light-emitting layer and the electron transport layer in organic light-emitting devices leads to a decrease in light emission efficiency due to low electron injectivity and impurity-related degradation of the charge injection/transport layer.
Innovation Solution
An organic light-emitting device configuration with a fluoride of an alkali metal or alkaline earth metal intermediate layer and a second charge injection/transport layer doped with an alkali metal or alkaline earth metal, along with varying thicknesses of charge injection/transport layers for different light emitters to enhance electron injectivity and block impurities, is employed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic barrier layer is disposed between the organic light-emitting layer and the electron transport layer, then impurity degradation of the charge injection/transport layer is suppressed, but light emission efficiency decreases
Solution Approach 1:
An intermediate layer comprising a fluoride of an alkali metal or alkaline earth metal is introduced between the organic light-emitting layer and the electron transport layer. This intermediate layer serves as a mediator that provides both impurity barrier functionality and high electron injectivity, thereby maintaining light emission efficiency while protecting against impurity degradation.
Solution Approach 2:
The electron transport layer is formed as a composite material by doping an organic material with an alkali metal or alkaline earth metal. This composite structure combines the benefits of organic materials (flexibility, processability) with the advantages of metal doping (enhanced electron transport and injectivity), achieving both high efficiency and stability.
2Loss of energy
If an electron transport layer with high electron injectivity is used, then light emission efficiency improves, but the layer becomes more susceptible to impurity degradation
Solution Approach 1:
The protective barrier function is segmented from the electron transport function. The intermediate layer comprising fluoride provides the barrier function against impurities, while the doped organic electron transport layer provides high electron injectivity. This segmentation allows each layer to be optimized for its specific function without compromise.
Solution Approach 2:
The intermediate layer acts as a protective intermediary between the organic light-emitting layer and the electron transport layer, shielding the high-performance but impurity-sensitive electron transport layer from degradation while maintaining its high electron injectivity capability.
3Reliability
If a fluoride intermediate layer is introduced to block impurities, then charge injectivity is maintained, but device structure becomes more complex
Solution Approach 1:
The intermediate layer comprising fluoride is designed to perform multiple functions simultaneously: blocking impurities, maintaining electron injectivity, and potentially serving as part of the optical cavity structure. This multi-functionality reduces the need for additional separate layers, thereby limiting the increase in device complexity.
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 configuration achieves high light emission efficiency while preventing impurity-induced degradation, maintaining high charge injectivity and storage stability, and optimizing optical path lengths for improved light emission.
Implementation Method 1
an intermediate layer comprising a fluoride of an alkali metal or a fluoride of an alkaline earth metal... is disposed between the organic light-emitting layer and the electron transport layer
Implementation Method 2
a second charge injection/transport layer comprising an organic material doped with an alkali metal or an alkaline earth metal... high electron injectivity can be achieved
Implementation Method 3
organic electroluminescence (EL) panels... organic light-emitting layer
Implementation Method 4
thickness of the one charge injection/transport layer in the first light emitter is different from thickness of the one charge injection/transport layer in the second light emitter... optimizing optical path lengths for improved light emission
Data Source
AI summary
A plurality of light emitters emitting different colors of light in a light-emitting device is provided on a surface of a substrate along two dimensions. Each light emitter includes a first electrode, a first charge injection/transport layer, a light-emitting layer, an intermediate layer, a second charge injection/transport layer, and a second electrode. The intermediate layer includes a fluoride of an alkali metal or an alkaline earth metal. Among the first electrode and the second electrode, one electrode is light reflective and another electrode is light transmissive. Among the first charge injection/transport layer and the second charge injection/transport layer, one charge injection/transport layer is disposed between the light-emitting layer and the light reflective electrode, and thickness of the one charge injection/transport layer included in the first light emitter is different from thickness of the one charge injection/transport layer included in the second light emitter.