OLED Display Substrate Light Shielding for TFT Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The light emitted from the light emitting layer in OLED devices affects the characteristics of low temperature poly-silicon thin film transistors, leading to instability in threshold voltage and off-state current, which compromises the display effect.
Innovation Solution
Incorporating a light shielding layer between the active layer and the first electrode in the OLED display substrate, which also serves as an insulating layer, with a transmittance of less than 10% for light at 600 nm or less, to block light from reaching the active layer and prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light shielding layer is added to block light from reaching the active layer, then the stability of threshold voltage and off-state current is improved, but the device complexity increases
Solution Approach 1:
The light shielding layer is merged with the insulating layer, making one layer serve dual functions: electrical insulation and light blocking. This combination eliminates the need for separate light shielding and insulating layers, thereby improving reliability without proportionally increasing device complexity
Solution Approach 2:
The insulating layer is designed to perform multiple functions simultaneously: providing electrical insulation between conductive layers and blocking light from reaching the active layer. This multi-functionality resolves the contradiction by adding light shielding capability without requiring an additional dedicated layer
2Object-affected harmful factors
If the light shielding layer is made of metal, then the light blocking effect is improved, but the risk of short-circuiting with other conductive patterns increases
Solution Approach 1:
An organic light shielding material is used as an intermediary between the light source and the active layer. This material provides effective light blocking while being electrically insulating, thereby preventing short-circuiting with other conductive patterns while maintaining the light shielding function
Solution Approach 2:
The material property of the light shielding layer is changed from conductive (metal) to insulating (organic material). This parameter change maintains the light blocking effect while eliminating the electrical conductivity that causes short-circuiting, thus resolving the contradiction between light blocking effectiveness and short-circuit risk
3Object-affected harmful factors
If separate light shielding layer and insulating layer are used, then the light blocking function is ensured, but the production process complexity and cost increase
Solution Approach 1:
The light shielding layer and insulating layer are merged into a single integrated layer. This reduces the number of manufacturing steps from forming separate layers to forming one combined layer, thereby simplifying the production process and reducing costs while ensuring both light blocking and insulation functions
Solution Approach 2:
The insulating layer is designed to perform multiple functions simultaneously: providing electrical insulation between conductive layers and blocking light from reaching the active layer. This multi-functionality resolves the contradiction by adding light shielding capability without requiring an additional dedicated layer, thus simplifying the manufacturing process
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 shielding layer stabilizes the light emitting characteristics, increases stability, and ensures display performance by preventing light from affecting the thin film transistor, while also serving as an insulating layer to avoid short-circuiting issues and reducing production complexity.
Implementation Method 1
the light shielding layer has a transmittance of less than 10% for light at a wavelength of 600 nm or less
Data Source
AI summary
The present disclosure provides an OLED display substrate, a method for preparing the same, and a flexible display device. The OLED display substrate includes a base substrate, and a thin film transistor, a first electrode and a light emitting layer sequentially arranged on the base substrate, the thin film transistor including an active layer, in which the OLED display substrate further includes a light shielding layer arranged between the active layer and the first electrode, and the light shielding layer also serves as an insulating layer of the OLED display substrate.