EL Device Protective Layers for Sealing and Short Circuit Prevention
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Solution Overview
Problem
Existing electroluminescent (EL) devices face issues with sealability due to potential short circuits and moisture intrusion, particularly when the cathode is misaligned, leading to compromised protection of the organic EL layer.
Innovation Solution
The EL device incorporates a substrate with a first electrode layer, an insulating layer, a first protective layer made of inorganic materials, an organic light-emitting layer, a second electrode layer, and a second protective layer that extends to cover the edges and outside of the organic layer, ensuring comprehensive sealing and preventing direct contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single protective film covers the element portion and ribs, then the structure is simple, but the sealability is insufficient and moisture can intrude through the projecting resin layer
Solution Approach 1:
The protective film is divided into multiple separate films: a first protective film covering the element portion and a second protective film covering the ribs and extending onto the front surface. This segmentation allows each film to be optimized for its specific location, with the second film providing extended sealing coverage to prevent moisture intrusion through the projecting resin layer while maintaining overall structural simplicity.
2Ease of manufacture
If the cathode is formed at a shifted position to simplify manufacturing, then ease of manufacture improves, but the cathode may contact the anode causing short circuits
Solution Approach 1:
A non-conductive layer is introduced as an intermediary between the anode and cathode. This layer extends from the rear surface of the element portion onto the front surface, creating a physical barrier that prevents direct contact between the anode and cathode even when the cathode is positioned at a shifted location. This allows manufacturing with higher positioning tolerance while maintaining reliable short circuit prevention.
3Reliability
If the protective film extends to cover edges and outside regions, then sealability and short circuit prevention improve, but device complexity increases
Solution Approach 1:
The second protective film is designed to perform multiple functions simultaneously: it covers the ribs for structural protection, extends onto the front surface to provide sealing against moisture intrusion, and works in conjunction with the non-conductive layer to prevent short circuits. This multi-functionality allows the extended protective structure to achieve enhanced reliability without proportionally increasing device complexity.
Data Source
AI summary
An EL device includes a substrate; a first electrode layer; an insulating layer having an opening corresponding to a pixel; a first protective layer covering the insulating layer; an organic layer on the first protective layer and the first electrode layer in the opening; a second electrode layer on the organic layer; and a second protective layer on the second electrode layer, wherein the second protective layer covers edges of the organic layer and the second electrode layer and extends to the outside of the forming region of the organic layer and the second electrode layer to contact the first protective layer.