OLED Shielding Electrode for Light Interference Control
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Solution Overview
Problem
Existing organic light emitting display (OLED) technologies face challenges in efficiently controlling the light emission of organic light emitting diodes (OLEDs) due to issues with voltage threshold and external light interference, which affect the reliability and display quality of OLEDs.
Innovation Solution
The implementation of a driving transistor with a shielding electrode configured to receive a power voltage, which is disposed on the second semiconductor active layer overlapping the driving transistor, helps to prevent external light from interfering with the channel region of the first transistor, thereby enhancing the reliability and display quality of OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional OLED structure without shielding electrode is used, then the device complexity is low, but external light interferes with the channel region causing threshold voltage instability and reduced reliability
Solution Approach 1:
A shielding electrode is introduced as an intermediary component between the external light environment and the transistor channel region. This electrode, positioned in the pixel structure, acts as a mediator that blocks or reduces external light interference from reaching the sensitive oxide semiconductor material in the channel, thereby stabilizing the threshold voltage without fundamentally changing the transistor operation principles
Solution Approach 2:
The shielding electrode adds a new spatial dimension to the pixel structure by introducing an additional layer above the transistor components. This dimensional addition creates a protective overhead layer that addresses the light interference problem from a different spatial perspective, rather than trying to modify the channel region itself
2Reliability
If oxide semiconductor material is used in the control transistor, then the threshold voltage stability is improved, but external light still affects the material causing display quality degradation
Solution Approach 1:
The shielding electrode serves as a protective intermediary that stands between the external light source and the oxide semiconductor material. By positioning this electrode above the transistor structure, it intercepts harmful light before it can reach and affect the sensitive oxide semiconductor channel material, thus preserving display quality while maintaining the benefits of oxide semiconductor usage
3Reliability
If the shielding electrode is added to protect from light interference, then the reliability is improved, but the manufacturing process complexity increases
Solution Approach 1:
The shielding electrode is merged with the existing pixel structure by integrating it into the ITO layer formation process. Rather than adding a completely separate manufacturing step, the shielding function is combined with the conductive layer deposition process, allowing the electrode to be formed simultaneously with other conductive elements in the pixel, thus reducing overall manufacturing complexity
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.