Oxide TFT Electroluminescent Display with Hydrogen-Blocking Drain Electrode
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Solution Overview
Problem
Current electroluminescent display devices using oxide thin-film transistors face challenges in reducing the number of mask processes, which affects productivity and increases material costs, and are vulnerable to hydrogen ingress that degrades transistor performance.
Innovation Solution
The proposed electroluminescent display device employs a reduced number of mask processes by forming the data line on the same layer as the first light-blocking layer and uses drain electrodes made of hydrogen-trapping materials to inhibit hydrogen entry, while also optimizing the layout of electrodes to reduce parasitic capacity and enhance charging rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of mask processes is reduced to improve productivity, then manufacturing efficiency increases, but manufacturing precision may deteriorate
Solution Approach 1:
The patent combines the data line and first light-blocking layer into the same layer structure, reducing the number of separate mask processes required. This merging approach maintains manufacturing precision by ensuring proper alignment through a single patterning step while improving productivity by eliminating redundant processing steps.
Solution Approach 2:
The first light-blocking layer is designed to serve multiple functions: it blocks light during display operation and simultaneously serves as the data line structure. This multi-functionality reduces the number of components and processing steps needed, thereby improving manufacturing efficiency without compromising the precision of individual components.
2Reliability
If hydrogen blocking structures are added to protect oxide thin-film transistors, then reliability improves, but device complexity increases
Solution Approach 1:
The drain electrode is designed to simultaneously serve as both the electrical contact structure and the hydrogen blocking structure. By using hydrogen-trapping materials for the drain electrode, the patent eliminates the need for separate hydrogen blocking layers, thereby improving transistor reliability while avoiding increased device complexity.
Solution Approach 2:
The drain electrode material itself provides the hydrogen blocking function through its inherent hydrogen-trapping properties. This self-service approach allows the same component to protect against hydrogen ingress without requiring additional protective structures, thus maintaining simplicity while improving reliability.
3Speed
If electrode layout is optimized to reduce parasitic capacity, then charging rate improves, but manufacturing complexity increases
Solution Approach 1:
The patent reduces parasitic capacity by utilizing vertical stacking of electrodes rather than horizontal separation. By arranging electrodes in different layers (z-dimension) rather than spreading them out in the same plane (x-y dimension), the design achieves faster charging rates while maintaining a compact footprint that simplifies manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves productivity, reduces material costs, enhances the reliability and performance of oxide thin-film transistors by minimizing hydrogen exposure, and increases the charging rate of storage capacitors.
Implementation Method 1
uses drain electrodes made of hydrogen-trapping materials to inhibit hydrogen entry
Implementation Method 2
when positive holes are injected into the light-emitting layer from the anode and electrons are injected into the light-emitting layer from the cathode, the injected electrons and positive holes are recombined and produce excitons in a light-emitting layer
Data Source
AI summary
An electroluminescent display device includes a substrate divided into a display area and a non-display area, a first light-blocking layer and a data line disposed on the substrate in the display area, a first buffer layer disposed on the first light-blocking layer and the data line, a semiconductor layer disposed on an upper portion of the first buffer layer and made of an oxide semiconductor, a gate insulating layer disposed on the semiconductor layer, a gate electrode disposed on the gate insulating layer, a protective layer and a first planarization layer disposed on an upper portion of the gate electrode, a drain electrode disposed on the protective layer exposed by removing a partial area of the first planarization layer, a second planarization layer disposed on the drain electrode and the first planarization layer, and a light-emitting element disposed on an upper portion of the second planarization layer and including an anode, a light-emitting part, and a cathode.