OLED Light Absorption Layers for IGZO TFT Reliability
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Solution Overview
Problem
Organic electroluminescence devices using IGZO as a semiconductor material are sensitive to light, particularly in the green and blue wavelength bands, leading to deterioration of thin film transistors, which affects the reliability of the devices.
Innovation Solution
Incorporating a first light absorption layer over the thin film transistor and a second light absorption layer under it, formed from materials like silicon, germanium, and gallium arsenide, to shield light emitted from the organic light emission layer and external light, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IGZO is used as semiconductor material in thin film transistors, then high mobility and transparency are achieved, but the transistors become sensitive to light (especially green and blue wavelengths) causing deterioration
Solution Approach 1:
A light absorption layer is introduced as an intermediary component between the light-emitting organic layer and the IGZO-based thin film transistor. This layer absorbs harmful light (particularly green and blue wavelengths) before it reaches the transistor, protecting the IGZO material from light-induced deterioration while allowing the display to maintain its high mobility and transparency advantages
Solution Approach 2:
The invention converts the harmful light that would otherwise deteriorate the IGZO transistor into a beneficial effect by using the light absorption layer to trap the harmful wavelengths. The absorbed light energy is dissipated harmlessly, while the transistor continues to benefit from IGZO's high mobility and transparency properties
2Reliability
If the organic light emission layer emits light toward the electrode with high transmittance, then the device achieves self-luminous property and reduced thickness, but the thin film transistor becomes exposed to emitted light causing deterioration
Solution Approach 1:
The device structure is segmented into distinct functional layers, with the light absorption layer specifically positioned between the organic light emission layer and the thin film transistor. This segmentation allows the light-emitting function to be separated from the transistor operation, enabling the transistor to be protected from self-generated light while maintaining the overall self-luminous property of the device
Solution Approach 2:
The light absorption layer serves as an intermediary that blocks harmful light generated within the organic light emission layer from reaching the thin film transistor. This intermediary layer protects the transistor from deterioration caused by self-generated light while allowing the device to maintain its thin and self-luminous characteristics
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 light absorption layers effectively prevent deterioration of the thin film transistors due to light exposure, enhancing the reliability and performance of the organic electroluminescence devices.
Implementation Method 1
a first light absorption layer formed over the thin film transistor between the thin film transistor and the organic light emission layer, wherein the first light absorption layer is configured to shield light emitted from the organic light emission layer
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An organic electroluminescence device (100) is disclosed which includes: a substrate (111); a thin film transistor (T) formed on the substrate (111); a first electrode (142) formed on the substrate (111) provided with the thin film transistor (T); an organic light emission layer (144) and a second electrode (145) sequentially formed on the first electrode (142); and a first light absorption layer (136) formed over the thin film transistor (T) and configured to shield light emitted from the organic light emission layer (144). As such, the organic electroluminescence device (100) employing the oxide thin film transistor (T) can secure reliability against light.