Hydrogen Blocking Layer in Oxide Semiconductor OLED Displays
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Solution Overview
Problem
The existing OLED display devices using amorphous silicon TFTs face limitations in mobility, leading to issues with large and high-resolution displays, and the deposition of silicon-based passivation layers at low temperatures results in hydrogen residues that cause threshold voltage shifts and reduced display quality due to thermal damage.
Innovation Solution
Incorporating a hydrogen blocking layer made of inorganic materials like indium-tin-oxide (ITO), indium-zinc-oxide (IZO), or metal alloys between the TFTs and the second passivation layer to prevent hydrogen diffusion, thereby maintaining the integrity of the oxide semiconductor material and enhancing display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon-based passivation layer is deposited at low temperature to prevent thermal damage to the emitting layer, then thermal damage is avoided, but hydrogen residues are generated that cause threshold voltage shifts and reduced display quality
Solution Approach 1:
A hydrogen blocking layer is introduced as an intermediary between the oxide semiconductor layer and the silicon-based passivation layer. This intermediate layer prevents hydrogen residues from the passivation layer from diffusing into the oxide semiconductor layer, thereby blocking the harmful effect while allowing the low-temperature deposition process to continue
Solution Approach 2:
The passivation structure is segmented into multiple functional layers: the hydrogen blocking layer specifically addresses hydrogen diffusion, while the silicon-based passivation layer provides overall protection. This segmentation allows each layer to perform its specialized function without compromising the other
2Ease of manufacture
If amorphous silicon TFTs are used in OLED display devices, then the fabrication process is simple and production cost is low, but mobility is limited to less than 1 cm2/Vsec which restricts large and high-resolution displays
Solution Approach 1:
The semiconductor material parameter is changed from amorphous silicon to oxide semiconductor, which fundamentally alters the mobility characteristic from less than 1 cm2/Vsec to higher values, enabling faster signal processing while maintaining compatibility with existing OLED fabrication processes
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 hydrogen blocking layer effectively prevents hydrogen diffusion, reducing defects such as brightness differences and improving the overall displaying quality of the OLED display device by maintaining the electrical properties of the oxide semiconductor material.
Implementation Method 1
hydrogen residues that diffuse into an oxide semiconductor layer through a planarization layer and a first passivation layer
Data Source
AI summary
An organic light emitting diode display device and method of fabricating the device according to an embodiment includes a substrate; an oxide semiconductor layer over the substrate; a planarization layer over the oxide semiconductor layer; an emitting diode over the planarization layer; a passivation layer over the emitting diode; and a hydrogen blocking layer between the planarization layer and the passivation layer to block hydrogen diffusion from the passivation layer to the oxide semiconductor layer.