Light Blocking Layer for Oxide Semiconductor OLED Stability
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Solution Overview
Problem
Active matrix type organic light-emitting displays face challenges in preventing light, water, and oxygen penetration, which affects the stability of oxide semiconductor thin-film transistors, especially when scaled up for large-sized displays and mass production, leading to potential product defects and reduced user convenience.
Innovation Solution
Incorporating a light blocking layer made of materials like manganese-doped barium titanate, titanium nitride, or electrochromic nickel oxide on the active layer to block specific wavelengths of light, such as blue light, and positioning it between the insulating layer and the source/drain electrodes to prevent direct light emission from the organic light emitting device from reaching the active layer, while also using an oxide semiconductor active layer and a passivation layer to enhance protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional TFT structure without light blocking layer is used, then the device structure is simpler and manufacturing is easier, but light from the OLED penetrates through the active layer causing instability and degradation of the oxide semiconductor
Solution Approach 1:
A light blocking layer is introduced as an intermediary component between the OLED and the TFT active layer. This layer specifically blocks light wavelengths that cause degradation of the oxide semiconductor while allowing the device to maintain its functional performance, thus resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The light blocking layer is positioned specifically in the region where light from the OLED would incidentally reach the active layer, providing localized protection only where needed. This approach maintains overall device simplicity while addressing the specific stability issue of the oxide semiconductor.
2Reliability
If the light blocking layer is added to block light penetration, then the stability of the oxide semiconductor is improved, but the device structure becomes more complex
Solution Approach 1:
The light blocking layer is designed with specific optical parameters - it blocks only the wavelengths of light that cause degradation of the oxide semiconductor while being transparent to other wavelengths. This selective parameter-based approach provides protection without requiring complete opacity, thus minimizing the impact on device complexity.
3Ease of manufacture
If oxide semiconductor is used in the active layer, then the display can be manufactured using low-temperature processes suitable for mass production, but the oxide semiconductor becomes sensitive to light-induced degradation
Solution Approach 1:
The light blocking layer is positioned to prevent light from reaching the oxide semiconductor active layer before the light-induced degradation can occur. This preliminary protective action allows the use of oxide semiconductor in low-temperature manufacturing processes while preventing the harmful effects of light exposure during device operation.
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 solution effectively blocks blue light emission, increasing the stability of the oxide semiconductor, reducing product defects, and enabling easier mass production of large-sized organic light-emitting displays with improved user convenience by preventing light-induced degradation.
Implementation Method 1
a light blocking layer that is on the active layer and that blocks light of a predetermined wavelength from the active layer
Implementation Method 2
an organic light emitting device that is electrically connected to one of the source and drain electrodes
Data Source
AI summary
An organic light emitting display includes a gate electrode on a substrate, an active layer insulated from the gate electrode, source and drain electrodes that are insulated from the gate electrode and contact the active layer, an insulating layer between the active layer and the source and drain electrodes, a light blocking layer that is on the active layer and that blocks light of a predetermined wavelength from the active layer, and an organic light emitting device that is electrically connected to one of the source and drain electrodes.