Low Resistance Cathode Wiring in Organic EL Display Devices
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Solution Overview
Problem
Organic EL display devices face challenges in achieving high brightness and contrast due to high resistance in cathode wiring, which increases the frame size and calorific value when trying to supply larger currents, as increasing the width or thickness of cathode wiring in the peripheral region hinders frame narrowing.
Innovation Solution
The cathode wiring is arranged in a layer lower than the transistor layer, electrically connected to the common electrode via a contact hole in the undercoat layer, allowing for increased width and thickness without occupying more space in the peripheral region, thus reducing resistance and frame size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width or thickness of cathode wiring is increased to reduce resistance, then the resistance decreases, but the frame size increases
Solution Approach 1:
The cathode wiring is moved from the peripheral region to the central region, utilizing the vertical dimension (different layers) to resolve the contradiction. The wiring is formed in a layer below the transistor layer, allowing it to extend across the central region without occupying additional peripheral space, thus reducing resistance while maintaining a compact frame size.
2Illumination intensity
If larger current is supplied to achieve high brightness, then the brightness increases, but the calorific value increases
Solution Approach 1:
The invention changes the physical parameters of the cathode wiring by moving it to a different layer and extending it across the central region. This configuration reduces the wiring resistance, allowing larger current to be supplied with lower energy loss, thereby increasing brightness while minimizing calorific value through improved electrical conductivity.
3Reliability
If the width or thickness of cathode wiring is increased to reduce resistance, then the resistance decreases, but the device complexity increases
Solution Approach 1:
The invention utilizes the vertical dimension by forming the cathode wiring in a layer below the transistor layer. This approach reduces resistance through extended wiring path in the central region without increasing horizontal dimensions or adding structural complexity, as the wiring naturally follows the layer configuration already present in the device.
Data Source
AI summary
The display device includes a substrate, a first wiring provided on the substrate, an insulating layer having a first contact hole, and provided on the first wiring, a plurality of pixels arranged in a display region on the first insulating layer, each of the plurality of pixels having a transistor and a light emitting element, a common electrode provided in common to the plurality of light emitting elements and electrically connected to the first wiring via the first contact hole in a peripheral region surrounding the display region.