Transparent Cathode Voltage Drop Prevention via Vertical Conductive Posts
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Solution Overview
Problem
Top emission type organic light emitting display devices experience significant voltage drops in their cathode electrodes due to the need for the cathode to be both conductive and transparent, which worsens with increasing device size.
Innovation Solution
The design incorporates electrical connection units that penetrate through the organic layer arrangement to connect the cathode wiring directly to the cathode electrode, ensuring uniform voltage distribution by applying voltage at multiple points, with these units being insulated from the organic emission layer and arranged between or surrounding unit pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode electrode is made transparent to allow light transmission in top emission type devices, then light transmission is improved, but voltage drop increases due to reduced electrical conductivity
Solution Approach 1:
The cathode electrode structure is segmented into multiple components: a transparent cathode electrode layer and separate electrical connection units (conductive posts) that penetrate through the organic layer arrangement. This segmentation allows the transparent electrode to maintain light transmission while the discrete conductive posts provide dedicated electrical connection paths to reduce voltage drop.
Solution Approach 2:
The electrical connection units act as intermediaries between the cathode wiring and the transparent cathode electrode. These conductive posts penetrate through the organic layer arrangement to establish direct electrical connection, serving as a mediator that bridges the gap between the wiring layer and the transparent electrode while minimizing voltage drop.
2Area of stationary object
If the device size is increased to improve display area, then aperture ratio is improved, but voltage drop becomes more severe
Solution Approach 1:
The electrical connection is segmented into multiple discrete connection points distributed across the device area. Multiple electrical connection units are arranged to connect different regions of the cathode electrode to the cathode wiring, creating multiple parallel current paths that reduce overall voltage drop across large device areas.
Solution Approach 2:
The electrical connection units extend in the vertical dimension by penetrating through the organic layer arrangement from the cathode wiring layer to the cathode electrode layer. This three-dimensional connection approach reduces the effective path length for current flow and provides direct electrical connection across the device thickness, mitigating voltage drop in large area devices.
Data Source
AI summary
An organic light emitting display device can prevent a voltage dropping in a cathode electrode. The organic light emitting display device includes a substrate, cathode wiring arranged on a surface of the substrate, an anode electrode arranged on the substrate and electrically insulated from the cathode wiring, an organic layer arrangement arranged on the anode electrode to form a plurality of unit pixels, a cathode electrode covering the organic layer arrangement and at least one electrical connection unit to electrically connect the cathode wiring to the cathode electrode.