OLED Driving TFT Structure for Stable Grayscale and Low Leakage
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Solution Overview
Problem
The complexity of forming polycrystalline silicon and oxide semiconductor layers in thin film transistors for OLED displays leads to increased process complexity and current fluctuation issues, limiting grayscale expression and optical reliability.
Innovation Solution
A driving thin film transistor configuration using a polycrystalline silicon semiconductor layer and an oxide semiconductor layer with a buffer layer, gate insulating layer, and light shielding layer is implemented, enhancing performance and reducing current fluctuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a polycrystalline silicon semiconductor layer is used for high driving speed, then carrier movement speed is improved, but current fluctuation increases and grayscale expression deteriorates
Solution Approach 1:
The patent uses a composite semiconductor structure combining polycrystalline silicon layer and oxide semiconductor layer. The polycrystalline silicon provides high carrier mobility for fast switching, while the oxide semiconductor layer suppresses current fluctuation and improves grayscale expression. This composite approach resolves the contradiction by leveraging the complementary strengths of both materials.
2Loss of energy
If an oxide semiconductor layer is used to block leakage current, then power consumption is reduced, but carrier movement speed decreases
Solution Approach 1:
The patent combines oxide semiconductor layer with polycrystalline silicon layer to create a composite structure where the oxide semiconductor effectively blocks leakage current while the polycrystalline silicon maintains high carrier mobility. This resolves the contradiction by distributing different functional requirements to different material layers.
3Adaptability or versatility
If separate processes are used for forming polycrystalline silicon and oxide semiconductor layers, then material optimization is improved, but manufacturing complexity increases
Solution Approach 1:
The patent integrates the formation of polycrystalline silicon layer and oxide semiconductor layer into a unified manufacturing process flow. By merging these previously separate processes into a coordinated sequence with shared process conditions and equipment requirements, the patent reduces overall manufacturing complexity while maintaining the ability to optimize each material independently.
Data Source
AI summary
An organic light emitting display device including a substrate, a light emitting element on the substrate, and a driving thin film transistor supplying drive current to the light emitting element is disclosed. The driving thin film transistor includes a buffer layer on the substrate, a first polycrystalline silicon semiconductor layer on the buffer layer, a first oxide semiconductor layer contacting the first polycrystalline silicon semiconductor layer while being disposed thereon and including a first channel region, a first source region, and a first drain region, a gate insulating layer covering the first oxide semiconductor layer and the first polycrystalline silicon semiconductor layer, a first gate electrode disposed on the gate insulating layer, a first source electrode connected to the first source region, a first drain electrode connected to the first drain region, and a first light shielding layer disposed under the first oxide semiconductor layer while overlapping therewith.