OLED Substrate Light-Shielding Layer for TFT Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Light emitted from the light-emitting layer in OLED devices affects the characteristics of the thin-film transistor, causing instability in threshold voltage and off-state current, particularly in low temperature poly-silicon transistors which are sensitive to light.
Innovation Solution
Incorporating a light-shielding layer made of amorphous silicon, optionally doped with sulfur, between the active layer and the first electrode of the thin-film transistor to block light emitted from the light-emitting layer, which can also be shared with existing insulating layers or planarization layers, and featuring depression portions to enhance light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light-emitting layer is placed above the thin-film transistor, then OLED light-emitting function is achieved, but light emitted from the light-emitting layer affects the thin-film transistor characteristics causing threshold voltage instability and increased off-state current
Solution Approach 1:
A light-shielding layer is introduced as an intermediary component between the light-emitting layer and the thin-film transistor active layer. This layer blocks light from reaching the active layer, preventing photoelectron generation and maintaining transistor stability while allowing the OLED to function normally
Solution Approach 2:
The OLED structure is segmented into distinct functional layers, with the light-shielding layer specifically positioned between the light-emitting layer and the active layer. This segmentation allows independent optimization of light emission and transistor stability without compromising either function
2Ease of manufacture
If low temperature poly-silicon is used for the thin-film transistor, then manufacturing flexibility and lower processing temperature are achieved, but the transistor becomes highly sensitive to light causing significant characteristic degradation
Solution Approach 1:
The light-shielding layer serves as a protective intermediary that shields the light-sensitive low temperature poly-silicon active layer from light exposure, enabling the use of this material without suffering from its light sensitivity drawbacks
Solution Approach 2:
The harmful light exposure is extracted or removed from the interaction path between the light-emitting layer and the active layer by introducing the light-shielding layer, thereby eliminating the harmful effect while preserving the benefits of low temperature poly-silicon
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 effectively stabilizes the light-emitting characteristics of OLED substrates by preventing light from affecting the thin-film transistor, improving light-emitting stability and reducing the impact of ambient light, while also enhancing light absorption through sulfur doping and depression portions.
Implementation Method 1
a light-shielding layer arranged between an active layer and the first electrode
Implementation Method 2
a material of which the light-shielding layer is made includes amorphous silicon, the OLED substrate further includes side layers arranged on two opposite sides of the light-shielding layer and in contact with the light-shielding layer, and a material of which the side layers are made is an insulating material
Data Source
AI summary
The present disclosure provides an OLED substrate and a display device. The OLED substrate includes a base substrate, and a thin-film transistor, a first electrode, and a light-emitting layer arranged in sequence on the base substrate, in which the OLED substrate further includes a light-shielding layer arranged between an active layer of the thin-film transistor and the first electrode.