Organic Electroluminescent Device Gas Barrier Layer Design
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Solution Overview
Problem
Organic electroluminescent devices face degradation due to moisture intrusion through the cathode line, which is exacerbated by the permeability of indium tin oxide (ITO) used in the wiring, leading to non-light-emitting 'dark spots' and reduced performance.
Innovation Solution
A gas barrier layer is applied over the wiring and light-emitting elements, including a transparent conductive layer and an organic buffer layer, to prevent moisture intrusion, while an electrode-protecting layer and protective substrate enhance the barrier's effectiveness, and the use of silicon nitride or silicon oxynitride provides high moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas barrier layer is formed to prevent moisture intrusion, then reliability is improved, but device complexity increases
Solution Approach 1:
The gas barrier layer is divided into multiple segments: a first gas barrier layer covering the cathode line and a second gas barrier layer covering the light-emitting elements. This segmentation allows targeted moisture protection where needed while avoiding unnecessary complexity in other regions, resolving the contradiction between reliability improvement and device complexity increase.
Solution Approach 2:
The patent applies gas barrier properties locally to specific regions requiring protection (cathode line and light-emitting elements) rather than uniformly across the entire device. The first gas barrier layer is specifically positioned at the cathode line where moisture intrusion occurs, and the second gas barrier layer protects the light-emitting elements, achieving reliable moisture protection with minimal added complexity.
2Area of stationary object
If the frame region is narrowed for design purposes, then area is improved, but ease of manufacture deteriorates
Solution Approach 1:
The gas barrier layer extends in the vertical dimension to provide moisture protection, compensating for the reduced horizontal space in the narrowed frame region. By utilizing the vertical dimension for barrier functionality, the patent achieves effective moisture protection despite the constrained frame width, resolving the contradiction between area optimization and manufacturing ease.
Solution Approach 2:
The first gas barrier layer is nested within or adjacent to the cathode line structure, and the second gas barrier layer is nested over the light-emitting elements. This nested arrangement maximizes the use of available space in the narrowed frame region while ensuring comprehensive moisture protection, making the device manufacturable despite the reduced frame width.
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 solution effectively minimizes moisture intrusion, reducing the formation of 'dark spots' and extending the service life of organic electroluminescent devices by ensuring a reliable gas barrier, thus maintaining high display performance.
Implementation Method 1
a gas barrier layer which is disposed over the entire surface of the substrate so as to cover end and top surfaces of the first connection line and top surfaces of the light-emitting elements
Implementation Method 2
the use of silicon nitride or silicon oxynitride provides high moisture resistance
Data Source
AI summary
An organic electroluminescent device includes a substrate; a plurality of light-emitting elements, each including an organic light-emitting layer held between a pair of electrodes; a display region which overlaps the substrate in plan view and in which the light-emitting elements are disposed; a first connection line which is disposed around the display region and is connected to one of the pair of electrodes and on which a transparent conductive layer is disposed; and a gas barrier layer covering end and top surfaces of the first connection line and top surfaces of the light-emitting elements.