Oxide TFT Light Shielding in OLED Display Pixel Circuits
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Solution Overview
Problem
OLED display devices using oxide semiconductors are prone to leakage currents due to external light exposure in bottom gate structures, which affects performance and increases manufacturing complexity.
Innovation Solution
A display device design with a first transistor using polycrystalline semiconductors and a second transistor using oxide semiconductors, where the oxide transistor channels are shielded by an external light blocking member to minimize leakage currents, and a mesh structure is used for driving voltage lines to enhance resolution and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bottom gate structure is used for oxide semiconductor transistors, then manufacturing cost is reduced and carrier mobility is improved, but leakage current increases due to external light exposure
Solution Approach 1:
An external light blocking member is introduced as an intermediary element between the oxide semiconductor channel and external light. This member blocks harmful light from reaching the channel while allowing the bottom gate structure to maintain its manufacturing advantages, thus resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The external light blocking member converts the harmful effect of external light into a beneficial structure by using the light blocking function to protect the oxide semiconductor channel. The same structural region that would normally be exposed is instead utilized to block light, transforming a vulnerability into a protective feature.
2Reliability
If oxide semiconductor is used instead of amorphous silicon, then carrier mobility and on/off ratio are improved, but manufacturing process complexity increases
Solution Approach 1:
The transistor manufacturing process is segmented into distinct regions: a first region for forming the oxide semiconductor layer and a second region for forming the external light blocking member. This segmentation allows each region to be optimized independently, reducing overall process complexity while maintaining the benefits of oxide semiconductor usage.
3Reliability
If external light blocking member is added to shield oxide semiconductor channels, then leakage current is reduced, but device complexity increases
Solution Approach 1:
The external light blocking member is merged with the existing transistor structure, specifically integrating it with the source/drain electrode regions. This merging approach reduces device complexity by combining multiple functions (light blocking and electrical connection) into a unified structure rather than adding separate independent components.
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
Minimizes leakage currents and reduces power consumption while maintaining high resolution and display quality by shielding oxide transistor channels from external light and optimizing transistor configurations.
Implementation Method 1
an external light blocking member positioned on the second source electrode and the second drain electrode and overlapping the second channel
Implementation Method 2
Electrons injected from a cathode that is an electrode and holes injected from an anode that is another electrode are bonded to each other in the organic light emitting layer to form excitons. Light is emitted while the excitons discharge energy.
Data Source
AI summary
A display device includes a substrate, first and second transistors on the substrate, a first electrode connected to one of the first and second transistors, a second electrode facing the first electrode, and a light emission member between the first and second electrodes, where the first transistor includes a first channel including a polycrystalline semiconductor member on the substrate, a first source electrode and a first drain electrode at respective opposite sides of the first channel, a first gate electrode overlapping the first channel, and a first insulating layer covering the first gate electrode, the second transistor includes a second gate electrode on the first insulating layer, a second channel including an oxide semiconductor member on the second gate electrode, second source and drain electrodes on the second channel, and an external light blocking member on the second source and drain electrodes and overlapping the second channel.