Insulating Layer Geometry for OLED Cathode Reliability
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Solution Overview
Problem
Organic electroluminescent devices face reliability issues due to short circuits caused by cracks in the cathode formed on the edge of metal wiring, leading to deterioration in device performance.
Innovation Solution
An insulating layer with a thickness of 0.3 to 30 times the thickness of the wiring is formed, with a side wall inclination angle of 10 to 55 degrees, to maximize contact area between the cathode and wiring, preventing electric field concentration and subsequent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode is formed on the edge of metal wiring, then electrical connection is achieved, but cracks occur in the cathode leading to short circuits
Solution Approach 1:
An insulating layer with controlled thickness (0.3 to 30 times the wiring thickness) and side wall inclination angle (10 to 55 degrees) is introduced as an intermediary between the cathode and metal wiring. This intermediary structure prevents direct contact at the edge where electric field concentration would cause short circuits, while still enabling smooth electrical connection through the optimized geometry that distributes the electric field evenly.
Solution Approach 2:
The insulating layer's thickness and side wall inclination angle are precisely controlled within specific ranges (thickness ratio of 0.3-30 times wiring thickness, angle of 10-55 degrees). By changing these geometric parameters, the electric field distribution is optimized to prevent concentration at edges, thereby eliminating short circuit risks while maintaining reliable electrical connection.
2Reliability
If the insulating layer thickness is increased, then short circuit prevention is improved, but contact area between cathode and wiring decreases
Solution Approach 1:
The insulating layer thickness is optimized within a specific range (0.3 to 30 times the wiring thickness). This parameter control ensures that the layer is thick enough to prevent short circuits by isolating the cathode from the wiring edge, yet thin enough to maintain adequate contact area for smooth electrical connection. The side wall inclination angle (10 to 55 degrees) further optimizes the transition geometry.
Solution Approach 2:
Instead of varying only the thickness (one dimension), the solution introduces the side wall inclination angle as an additional geometric parameter. This angular dimension allows the insulating layer to provide sufficient thickness for isolation while creating a gradual transition that maintains contact area, effectively resolving the contradiction through multi-dimensional geometric optimization.
Data Source
AI summary
An organic electroluminescent device is provided having a metal wiring in a non-light-emitting region. The device may include a substrate, a wiring formed on the substrate to electrically connect to an external circuit, an insulating layer formed on the wiring such that the wiring is partially exposed. The insulating layer having a thickness 0.3 to 30 times a thickness of the wiring.