OLED Black Matrix with Variable Light Transmittance for Flexible Displays
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Solution Overview
Problem
Conventional OLED displays are not flexible due to the use of thick circular polarizing films, which hinder their ability to be folded or rolled, limiting their application in flexible display technologies.
Innovation Solution
The implementation of a black matrix with a first light-blocking unit in the non-emission area and a second light-blocking unit in the emission area, where the second unit has higher light transmittance and a thinner thickness, allowing for improved visibility and flexibility without the need for a polarizer, and including a thin film encapsulating layer to enhance encapsulation and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thick circular polarizing film is used in conventional OLED displays, then external light reflection is blocked, but the display becomes non-flexible and cannot be folded or rolled
Solution Approach 1:
The invention extracts and eliminates the circular polarizing film from the OLED display structure. By removing this thick component that prevents flexibility, the display can be folded or rolled while maintaining the ability to block external light reflection through alternative means (the black matrix structure with light-blocking units)
Solution Approach 2:
The invention applies local quality by creating a black matrix with spatially varying light-blocking properties. The light-blocking units are strategically positioned and dimensioned to provide different degrees of light reflection blocking in different areas, achieving effective external light rejection without requiring a uniform thick polarizing film across the entire display
2Object-affected harmful factors
If a thick circular polarizing film is used, then external light reflection is minimized, but the display thickness increases and flexibility is lost
Solution Approach 1:
The invention removes the thick circular polarizing film that contributes significantly to display thickness. The alternative black matrix structure provides comparable external light reflection blocking with minimal thickness increase, enabling thin and flexible display design
Solution Approach 2:
The invention changes the structural parameters of the light-blocking mechanism. Instead of using a thick polarizing film with specific optical properties, the black matrix uses a different structural approach (light-blocking units with specific dimensions and spacing) to achieve similar light reflection blocking with reduced thickness
3Use of energy by moving object
If the black matrix has high light transmittance in the emission area, then light extraction efficiency is maintained, but visibility may be compromised
Solution Approach 1:
The invention applies local quality by creating spatially differentiated light-blocking units within the black matrix. In the emission area, light-blocking units are designed with dimensions and spacing that allow sufficient light transmission for efficient light extraction, while in the non-emission area, they provide stronger light blocking for visibility. This local optimization resolves the contradiction between light extraction efficiency and visibility
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
This configuration enhances visibility by minimizing external light reflection and allows for the production of flexible OLED displays that maintain light extraction efficiency similar to polarized displays, without the thickness constraints of traditional polarizing films.
Implementation Method 1
Holes injected from the hole injection electrodes and electrons injected from the electron injection electrodes combine in the organic emission layers and generate excitons. Thus, light is generated as the excitons drop from an excited state to a ground state.
Implementation Method 2
A visible light transmittance of the first light-blocking unit can be about 0.2% or less
Implementation Method 3
a visible light transmittance of the second light-blocking unit can be about 40% to about 70%
Data Source
AI summary
Organic light-emitting diode (OLED) displays and methods of manufacturing OLD displays are disclosed. In one aspect, an OLED display includes a substrate having an emission area and a non-emission area, a pixel electrode formed in the emission area, and an intermediate layer formed over the pixel electrode and including an organic emission layer. The display also includes an opposite electrode formed in the emission and non-emission areas and at least partially covering the intermediate layer. The display further includes a black matrix formed over the opposite electrode and including a first light-blocking portion formed in the non-emission area and a second light-blocking portion formed in the emission area and having light transmittance greater than that of the first light-blocking portion.