OLED Pixel Circuit Layout for Low-Leakage Oxide TFT Stability
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face challenges in improving display quality due to leakage currents in transistors, which affect reliability and stability, particularly in oxide semiconductor layers, and require additional processes to stabilize transistor characteristics without increasing the number of processes.
Innovation Solution
The implementation of an organic light emitting diode display structure that includes a polycrystalline semiconductor layer, insulating films, and an oxide semiconductor layer, with a specific overlapping layer configuration to stabilize the oxide semiconductor transistor and reduce leakage currents, using a conductor structure that applies a driving voltage to maintain constant voltage across the oxide semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If oxide semiconductor layer is used in transistor, then device integration is enabled, but leakage current increases and reliability decreases
Solution Approach 1:
An overlapping layer is introduced as an intermediary component between the gate electrode and the oxide semiconductor layer. This overlapping layer mediates the electrical interaction, allowing the transistor to function while reducing the harmful leakage current through the oxide semiconductor, thus resolving the contradiction between enabling device integration and maintaining transistor reliability
2Reliability
If additional processes are added to stabilize transistor characteristics, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The overlapping layer is formed simultaneously with the gate electrode in the same manufacturing process step, merging two structures that could have been created separately. This integration approach stabilizes transistor characteristics by establishing proper electrical connections without requiring additional independent process steps, thus improving reliability without increasing manufacturing complexity
Data Source
AI summary
An organic light emitting diode display includes a first thin film transistor of which a channel is formed in a polycrystalline transistor, a second thin film transistor of which a channel is formed in an oxide semiconductor layer, an organic light emitting diode electrically connected to the first thin film transistor, a storage capacitor having a first electrode and a second electrode, wherein the second electrode of the storage capacitor is electrically connected to a gate electrode of the first thin film transistor, and an overlapping layer overlapping the oxide semiconductor layer in a plan view and receiving a positive voltage. The oxide semiconductor layer is positioned higher than the gate electrode of the first thin film transistor and the second electrode of the storage capacitor.