OLED Driving Transistor Contact Hole Reduction via Electrode Merging
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Solution Overview
Problem
Conventional active matrix organic light emitting diode devices have a reduced design area for driving transistors due to the presence of multiple transistors per pixel, leading to increased current stress and shortened transistor lifespan, which in turn shortens the device's lifespan.
Innovation Solution
The solution involves reducing the number of contact holes to minimize the area occupied by them, allowing for a larger design margin for the driving transistor by electrically connecting the gate electrode of a first transistor to the source electrode of a second transistor through a single contact hole, thereby reducing current stress on the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transistors are disposed per pixel in conventional active matrix OLED devices, then the device can achieve active matrix driving capability, but the design area of the driving transistor is reduced and current stress increases
Solution Approach 1:
The patent merges the gate electrode of the first transistor and the source electrode of the second transistor into a single integrated electrode structure. This merging eliminates the need for separate contact holes for each electrode, reducing the total area occupied by contact holes and thereby expanding the design area of the driving transistor while maintaining active matrix driving capability.
Solution Approach 2:
The integrated electrode structure serves multiple functions simultaneously: it acts as both the gate electrode for the first transistor and the source electrode for the second transistor. This multi-functionality reduces the number of separate components needed, minimizing contact hole area and improving transistor reliability through reduced current stress.
2Reliability
If multiple contact holes are used to connect transistors, then electrical connections can be established, but the area occupied by contact holes increases
Solution Approach 1:
The patent combines multiple contact holes into a single contact hole by merging the gate electrode and source electrode structures. This merging reduces the total area occupied by contact holes from multiple separate openings to one consolidated opening, thereby increasing the design area available for the driving transistor and improving overall device reliability.
3Reliability
If multiple contact holes are used for transistor interconnection, then electrical connectivity is achieved, but current stress on the driving transistor increases
Solution Approach 1:
The patent merges the gate electrode of the first transistor with the source electrode of the second transistor into a single integrated structure. This merging reduces the number of contact holes from multiple to one, thereby reducing the total contact resistance and current stress on the driving transistor, which extends transistor lifespan and improves reliability.
Data Source
AI summary
An organic light emitting diode device includes a gate electrode of a first transistor on a substrate; a gate insulation film on the gate electrode of the first transistor; a source electrode of a second transistor on the gate insulation film and overlapping with the gate electrode of the first transistor; a contact hole exposing the gate electrode of the first transistor and the source electrode of the second transistor; a conductive wiring in the contact hole, for electrically connecting the gate electrode of the first transistor and the source electrode of the second transistor.