Polysilazane Gas Barrier for Flexible Organic EL Dark Spots
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Solution Overview
Problem
Organic electroluminescent elements using resin substrates face challenges in preventing dark spot generation and maintaining high storage stability, luminescence efficiency, and uniformity, especially under high temperature and high humidity conditions, due to the deterioration of gas barrier properties and light emission efficiency caused by oxidation reactions and light reflection phenomena.
Innovation Solution
The implementation of a flexible organic electroluminescent element structure comprising a polysilazane reforming layer as a first gas barrier, a metal oxide insulating layer with a lower redox potential than silicon, and a second gas barrier layer containing silicon, carbon, and oxygen, which are formed using energy impression and gas phase layer formation techniques, respectively, to control oxidation reactions and enhance light emission uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polysilazane reforming layer is used as a gas barrier layer in flexible organic EL elements, then the gas barrier property is improved, but dark spots are generated after long-term storage under high temperature and high humidity conditions
Solution Approach 1:
An insulating layer containing metal oxide with lower redox potential than silicon is introduced as an intermediary layer between the polysilazane reforming layer and the electrode. This intermediary layer prevents oxidation reactions at the interface, thereby preventing dark spot generation while maintaining the gas barrier properties of the polysilazane layer.
Solution Approach 2:
The harmful oxidation reaction at the interface between the polysilazane layer and electrode is extracted and isolated by introducing the insulating layer. This separates the gas barrier function (polysilazane layer) from the oxidation-prone interface, eliminating the dark spot issue.
2Reliability
If a polysilazane reforming layer is used as a gas barrier layer, then the gas barrier property is improved, but light emission efficiency and uniformity deteriorate due to light reflection at the interface
Solution Approach 1:
The insulating layer acts as an optical intermediary with appropriate refractive index, reducing light reflection at the interface between the polysilazane layer and electrode. This improves light emission efficiency and uniformity while preserving the gas barrier function.
3Object-affected harmful factors
If a metal oxide insulating layer with lower redox potential than silicon is introduced, then oxidation reactions are controlled and dark spot generation is prevented, but the device structure becomes more complex
Solution Approach 1:
The insulating layer with metal oxide serves multiple functions simultaneously: it provides oxidation protection, controls redox reactions, and maintains electrical insulation. This multi-functionality justifies the additional layer by consolidating several protective roles into one component.
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 effectively prevents dark spot generation, maintains high storage stability and luminescence efficiency, and achieves uniform light emission even under harsh conditions by controlling oxidation reactions and reducing light reflection, thereby improving the overall performance of the organic electroluminescent element.
Implementation Method 1
it is required a gas barrier property of extremely high level almost as high as a glass substrate. In particular, it is demanded an organic EL element which can prevent generation of dark spots even keeping for a long term under the condition of high temperature and high humidity
Implementation Method 2
the insulating layer is a layer containing a metal oxide; and a metal element in the metal oxide has a lower redox potential than silicon
Implementation Method 3
the aforesaid insulating layer is a layer formed by gas phase layer formation with a metal oxide
Implementation Method 4
the first gas barrier layer is a polysilazane reforming layer which is formed by impressing energy to a coating layer containing polysilazane
Implementation Method 5
An organic electroluminescence element is a thin-type complete solid element utilizing electroluminescence produced by an organic material
Data Source
AI summary
The present invention provides an organic electroluminescent element containing a flexible substrate having thereon: a first gas barrier layer, an insulating layer, a first electrode, a light emitting unit containing an organic functional layer, and a second electrode, in that order, wherein the first gas barrier layer is a polysilazane reforming layer; the insulating layer is a layer containing a metal oxide; and a metal element in the metal oxide has a lower redox potential than silicon.