Organic EL Device Moisture Protection via Overlapping Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic EL devices face degradation due to moisture and oxygen infiltration, leading to dark spot formation and reduced light emission efficiency, particularly with polymer and resin substrates that release moisture and oxygen, and existing barrier layers are inadequate in preventing pinhole formation and substrate irregularities.
Innovation Solution
The organic EL device features a substrate with alternating first and second transparent electrode elements made of conductive metal oxides like SnO2, In2O3, and IZO, overlapping at their side edges through an insulation layer, and a substrate passivation layer of inorganic oxides to effectively block moisture and oxygen, ensuring comprehensive protection of the organic EL layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer barrier layer (organic resin or inorganic oxide) is used to prevent moisture and oxygen, then the device structure is simple, but the barrier layer develops pinholes and cannot effectively prevent moisture/oxygen infiltration
Solution Approach 1:
The patent applies composite materials by combining multiple barrier layers with different properties: an organic resin layer (polyimide-modified silicone resin) and an inorganic oxide layer (SiOx or SiNx) are stacked together. This composite structure leverages the advantages of both materials - the organic layer provides flexibility and adhesion while the inorganic layer provides pinhole-free moisture barrier, achieving effective moisture and oxygen prevention that neither material could achieve alone.
Solution Approach 2:
The patent implements nesting by placing one barrier layer inside another - the inorganic oxide barrier layer is positioned between the organic resin barrier layer and the organic EL layer. This nested multi-layer structure creates redundant protection paths, ensuring that even if one layer has defects, the other layers continue to block moisture and oxygen infiltration.
2Adaptability or versatility
If polymer or resin substrates are used for flexibility and transparency, then the substrate properties are improved, but moisture and oxygen are released from the substrate during operation, causing dark spot growth
Solution Approach 1:
The patent extracts and isolates the harmful moisture and oxygen release function from the substrate by introducing a dedicated substrate passivation layer made of inorganic oxide. This layer specifically addresses the substrate's harmful property (moisture/oxygen release) while allowing the substrate to retain its beneficial properties (flexibility and transparency). The passivation layer acts as a separate functional element that counters the substrate's harmful emissions.
Solution Approach 2:
The substrate passivation layer serves as an intermediary between the polymer substrate and the organic EL layer. It mediates the interaction by blocking the harmful moisture and oxygen released from the substrate before they can reach the organic EL layer, while still allowing the substrate to maintain its structural and optical functions.
3Quantity of substance
If the transparent electrode elements are arranged with gaps to reduce material usage, then the device cost is reduced, but moisture and oxygen can infiltrate through the gaps, causing dark spot formation
Solution Approach 1:
The patent applies multi-functionality by designing the insulation layer to serve dual purposes: (1) providing electrical insulation between adjacent transparent electrode elements, and (2) acting as an additional moisture and oxygen barrier covering the gaps between electrodes. This eliminates the need for separate protective structures, maintaining material efficiency while preventing infiltration through the gaps.
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 and maintains long-term light emitting performance by ensuring that moisture and oxygen are blocked from reaching the organic EL layer, thereby extending the device's operational lifespan and maintaining high brightness.
Implementation Method 1
provision of an inorganic oxide layer having a thickness in the range of 0.01 to 200 μm... Such an inorganic oxide layer must be highly moisture proof in order to maintain a long life of the organic light emitting layer
Implementation Method 2
provision of an organic resin such as polyimide-modified silicone resin... to prevent moisture from invading an organic EL device
Implementation Method 3
The first transparent electrode elements and the second transparent electrode elements can be formed of a material selected from the group consisting of SnO2, In2O3, ITO, IZO, and ZnO:Al
Implementation Method 4
an organic EL layer formed on the transparent electrode... maintaining long-term light emitting performance
Data Source
AI summary
An organic EL device is disclosed that prevents degradation due to moisture and oxygen and that avoids the generation of dark spots even when a substrate covered with polymer or made of a resin is used. The organic EL device includes a substrate, a transparent electrode consisting of a plurality of electrode elements formed on the substrate, an organic EL layer formed on the transparent electrode, and a reflection electrode formed on the organic EL layer. The transparent electrode includes first and second transparent electrode elements. Each of the first transparent electrode elements is arranged alternately with each of the second transparent electrode elements. A side edge portion of each of the first transparent electrode elements overlaps a side edge portion of next second transparent electrode element through an insulation layer. The first transparent electrode elements are electrically insulated from the second transparent electrode elements.