Organic EL Device Planar TFT Electrode Layout
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Solution Overview
Problem
Conventional Organic Electro-Luminescence (OEL) devices face challenges in connecting switching TFTs and driving TFTs through contact holes, particularly in high-definition active OEL displays, leading to lower yield and reliability.
Innovation Solution
The OEL device design features semiconductor elements A and B with source, drain, and gate electrodes positioned on the same plane, allowing for secure connection without contact holes, utilizing a top-gate and bottom-gate TFT configuration to improve electrode line thickness and response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are used to connect switching TFT and driving TFT, then device structure is established, but connection reliability deteriorates and yield decreases
Solution Approach 1:
The invention extracts and eliminates the contact hole structure from the device architecture. By removing the need for contact holes to connect the switching TFT and driving TFT, the patent directly addresses the reliability issues and yield problems associated with contact hole formation and alignment, while simplifying the overall device structure.
Solution Approach 2:
The patent transitions from a vertical connection approach (through contact holes) to a planar connection approach (on-surface wiring). The gate electrode of the driving TFT is extended to connect with the source or drain electrode of the switching TFT on the same surface, changing the dimensional approach from vertical penetration to lateral extension, thereby eliminating contact hole-related reliability issues.
2Productivity
If conventional top-emission structure is used, then light emission is achieved, but connection between TFTs becomes difficult and yield decreases
Solution Approach 1:
The patent merges the gate electrode of the driving TFT with the source/drain electrode of the switching TFT by extending the gate electrode onto the same surface. This merging of functions and structures eliminates the need for separate contact hole connections, thereby improving manufacturing yield and ease of connection while maintaining the top-emission light emission structure.
3Manufacturing precision
If contact holes are implemented for TFT connection, then electrical connection is established, but manufacturing precision requirements increase and yield decreases
Solution Approach 1:
The invention extracts the contact hole formation step from the manufacturing process. By eliminating contact holes entirely and using on-surface extension of the gate electrode for connection, the patent removes the stringent alignment and precision requirements associated with contact hole formation, thereby improving manufacturing yield without sacrificing connection precision.
Data Source
AI summary
An organic EL device comprising a semiconductor element A having a source electrode, a drain electrode, and a gate electrode, a semiconductor element B having a source electrode, a drain electrode, and a gate electrode connected to the source electrode or the drain electrode of the semiconductor element A, and an organic EL element having a pixel electrode connected to the drain electrode of the semiconductor element B, in which the source electrode and the drain electrode of the semiconductor element A and the gate electrode of the semiconductor element B are set on the same plane.