OLED Pixel Driving Transistor Shielding Against Light Exposure
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Solution Overview
Problem
Current organic light emitting display apparatuses face challenges in maintaining reliable operation and display quality due to issues with light exposure affecting the semiconductor active layers, particularly those using oxide semiconductor materials, which can lead to variations in threshold voltage and reduced performance.
Innovation Solution
Incorporating a shielding electrode configured to receive the power voltage and overlap the driving transistor's channel region, this shields the oxide semiconductor material from external light, preventing performance deterioration and ensuring consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor material is used in the transistor active layer, then transistor performance is improved, but light exposure causes threshold voltage variation and reduced reliability
Solution Approach 1:
A shielding electrode is introduced as an intermediary element between the light source and the oxide semiconductor active layer. This electrode, positioned in the pixel structure, acts as a physical barrier that blocks light from reaching the semiconductor material, thereby preventing light-induced threshold voltage variations while allowing the transistor to maintain its improved performance characteristics
Solution Approach 2:
The solution moves from a two-dimensional planar structure to a three-dimensional stacked structure by adding the shielding electrode above the active layer. This vertical arrangement creates a protective overhead layer that blocks light paths without interfering with the horizontal electrical connections and transistor operation, effectively separating the light exposure dimension from the semiconductor active layer
2Stability of the object's composition
If shielding electrode is added to prevent light exposure, then transistor operation stability is improved, but device complexity increases
Solution Approach 1:
The shielding electrode is designed to serve multiple functions within the pixel structure: it acts as a light shield to protect the semiconductor, simultaneously functions as an electrical connection element, and can be integrated with existing pixel components. This multi-functionality reduces the need for separate dedicated shielding structures, thereby limiting the increase in device complexity
Solution Approach 2:
The shielding electrode is merged with other pixel structure elements rather than being a completely separate component. By combining the shielding function with existing structural or electrical elements in the pixel, the design achieves light protection without proportionally increasing the number of discrete components, thus managing device complexity
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
The shielding electrode enhances the reliability of the control transistor, maintaining stable voltage and improving display quality by preventing light exposure and voltage coupling effects, thus ensuring consistent and high-quality organic light emitting display performance.
Implementation Method 1
a shielding electrode disposed over the channel region of the driving transistor and configured to receive the power voltage
Data Source
AI summary
An organic light emitting display (OLED) device includes an organic light emitting diode having an anode and a cathode. The organic light emitting diode is configured to receive a reference voltage. A control transistor includes a first control electrode and a first semiconductor active layer. The control transistor is configured to receive a control signal. A driving transistor includes a second control electrode that is electrically connected to the control transistor, an input electrode that is configured to receive a power voltage, an output electrode that is electrically connected to the anode of the organic light emitting diode, and a second semiconductor active layer that includes a different material from that of the first semiconductor active layer. A shielding electrode is disposed on the second semiconductor active layer, overlapping the driving transistor, and configured to receive the power voltage.