Black Matrix Structure for OLED Displays
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Solution Overview
Problem
Conventional black matrix structures in OLED displays contain toxic materials that cause environmental pollution and have insufficient electrostatic discharge resistance, leading to poor contrast and increased power consumption due to the use of chromium-based materials and polarizing films.
Innovation Solution
A black matrix structure comprising a semiconductor layer and a light-shielding layer, where the semiconductor layer is made of silicon or germanium and the light-shielding layer includes metals like titanium, nickel, or alloys, providing improved anti-reflective properties and electrostatic charge protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If chromium-based materials (chromium oxide, chromium nitride, chromium) are used in the black matrix structure, then the contrast is improved by absorbing environmental light, but toxic substances (Cr6+) are produced during etching processes causing environmental pollution
Solution Approach 1:
The patent changes the material composition parameters of the black matrix structure by replacing chromium-based materials with a multi-layer structure consisting of a semiconductor layer (amorphous silicon or microcrystalline silicon) and a light-shielding layer (metal oxide or metal). This material substitution eliminates toxic Cr6+ production during etching while maintaining the light-absorbing function for improved contrast.
Solution Approach 2:
The patent employs a composite material structure combining a semiconductor layer with a light-shielding layer. The semiconductor layer (amorphous silicon or microcrystalline silicon) provides light absorption capabilities, while the light-shielding layer (metal oxide such as tungsten oxide, molybdenum oxide, or metal such as tungsten, molybdenum, aluminum) enhances the light-blocking effect. This composite approach achieves effective contrast improvement without using toxic chromium-based materials.
2Illumination intensity
If chromium-based materials are used in the black matrix structure, then the light absorption is enhanced, but the resistance to electrostatic discharge is insufficient making the OLED display vulnerable to damage
Solution Approach 1:
The patent changes the material parameters by introducing a semiconductor layer made of amorphous silicon or microcrystalline silicon, which possesses both light-absorbing properties and electrostatic discharge resistance. This material parameter change simultaneously improves light absorption for contrast enhancement and provides reliability against electrostatic damage.
Solution Approach 2:
The composite structure of semiconductor layer plus light-shielding layer creates a material system that combines optical properties (light absorption) with electrical properties (electrostatic discharge resistance). The semiconductor layer absorbs light to improve contrast while inherently providing protection against electrostatic discharge, solving both requirements simultaneously.
3Illumination intensity
If a polarizing film is disposed on the surface of the substrate to reduce environmental light reflection, then the contrast is improved, but the transmittance of emitted light is reduced to about 43% resulting in reduced brightness and increased power consumption
Solution Approach 1:
The patent extracts the light-absorbing function from the polarizing film location and relocates it to the black matrix structure on the rear surface of the substrate. By placing the semiconductor layer and light-shielding layer in the black matrix, the patent eliminates the need for a front-surface polarizing film, allowing emitted light to pass through with higher transmittance and brightness while still achieving contrast improvement through environmental light absorption.
Solution Approach 2:
The patent moves the contrast-enhancing function from the optical path dimension (front surface polarizing film affecting light transmission) to the structural dimension (rear surface black matrix structure absorbing environmental light). This dimensional relocation allows the emitted light to maintain high transmittance and brightness while the black matrix structure on the rear surface absorbs reflected environmental light to improve contrast.
4Illumination intensity
If a polarizing film is used to reduce environmental light reflection, then the contrast is improved, but the thickness of the panel is increased and the yield rate of the coating process is affected
Solution Approach 1:
The patent extracts the contrast-enhancing function from the polarizing film and relocates it to the black matrix structure. By removing the polarizing film from the front surface, the patent reduces panel thickness and simplifies the coating process while maintaining contrast improvement through the rear-surface black matrix structure that absorbs environmental light.
Solution Approach 2:
The patent relocates the contrast-enhancing function from the front-surface optical path (adding thickness) to the rear-surface structural layer (black matrix). This dimensional shift eliminates the need for additional front-surface coating layers, reducing overall panel thickness and improving manufacturing yield while achieving the same contrast improvement goal.
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 enhances anti-reflective capabilities and prevents damage from electrostatic discharge, reducing environmental pollution and power consumption while maintaining high brightness and contrast in OLED displays.
Implementation Method 1
the black matrix structure 10 will absorb part of the environmental light to reduce the reflection
Implementation Method 2
a light-shielding layer positioned on the first surface of the semiconductor layer
Data Source
AI summary
A BM (black matrix) structure has a semiconductor layer and a light-shielding layer. The semiconductor layer has a first surface and a second surface. The light-shielding layer is disposed on the first surface of the semiconductor layer, and the second surface is an incident plane of environmental light.