OLED Light Blocking Layer for Contrast and Thickness
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Solution Overview
Problem
Organic light emitting diode displays face issues with reduced light emitting efficiency and increased thickness due to external light reflection, which deteriorates contrast and visibility, especially when used outdoors, and the presence of polarizing plates that hinder light transmission and increase thickness.
Innovation Solution
Incorporating a light blocking layer made of materials like carbon black, carbon nanotubes, or conductive metals on the organic light emitting diode display, which reduces external light reflection and replaces the polarizing plate, allowing for improved light efficiency and a thinner display design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizing plate is used to block external light reflection, then contrast and visibility are improved, but light emitting efficiency decreases and thickness increases
Solution Approach 1:
The patent removes the polarizing plate from the display structure entirely and replaces it with a light blocking layer made of transparent conductive oxide materials. This extraction of the harmful element (polarizing plate) eliminates its light-blocking effect while the new light blocking layer provides reflection protection through a different mechanism that does not interfere with light emission from the OLED.
Solution Approach 2:
The patent changes the material parameter from polarizing plate materials to transparent conductive oxide materials for the light blocking layer. This parameter change allows the layer to block external light reflection while maintaining high transparency to emitted light, thus improving both contrast and light emitting efficiency simultaneously.
2Object-affected harmful factors
If a polarizing plate is used to block external light reflection, then contrast and visibility are improved, but display thickness increases
Solution Approach 1:
The patent extracts and removes the thick polarizing plate from the display stack and replaces it with a thin light blocking layer made of transparent conductive oxide. This extraction eliminates the need for the bulky polarizing plate while achieving the same light blocking function with minimal thickness addition.
Solution Approach 2:
The patent employs a thin film light blocking layer made of transparent conductive oxide materials that provides effective light blocking functionality in a extremely thin form factor. This thin film approach replaces the thick polarizing plate and enables ultra-thin display designs while maintaining outdoor visibility.
3Object-affected harmful factors
If multiple layers (pixel defining layer, polarization film, phase difference film, color filter) are stacked to form the display panel, then light blocking function is achieved, but combined thickness increases and light emitting efficiency decreases
Solution Approach 1:
The patent merges the light blocking function with the transparent conductive oxide layer that already serves as an electrode or interface layer in the OLED structure. By combining multiple functions into a single layer, the patent eliminates the need for separate polarizing and phase difference films, reducing total thickness while maintaining light blocking effectiveness.
Solution Approach 2:
The transparent conductive oxide light blocking layer serves multiple functions simultaneously: it blocks external light reflection, maintains electrical conductivity, and provides a thin form factor. This multi-functional layer replaces several separate layers (polarizing film, phase difference film) with a single universal element.
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 outdoor visibility by preventing contrast and luminance deterioration, increases light efficiency, and reduces the display's thickness, making it suitable for flexible and ultra-thin applications.
Implementation Method 1
a light blocking layer on the second electrode and exposing the second electrode at a position corresponding to the pixel area
Implementation Method 2
Electrons injected from a cathode, which is one of the electrodes, and holes injected from an anode, which is another one of the electrodes, are combined with each other in the organic light emitting layer to form excitons. The formed excitons emit energy, such that the organic light emitting element emits light.
Data Source
AI summary
An organic light emitting diode display includes a substrate, a thin film transistor on the substrate, a first electrode on and connected to the thin film transistor, a pixel defining layer on the first electrode and defining a pixel area, an organic light emitting layer on the first electrode and contacting the first electrode exposed in the pixel area, a second electrode on the organic light emitting layer, and a light blocking layer on the second electrode and exposing the second electrode at a position corresponding to the pixel area. The light blocking layer may include a first metal layer on the second electrode and exposing the second electrode at a position corresponding to the pixel area, a first intermediate layer covering the first metal layer, a second metal layer covering the first intermediate layer, and a second intermediate layer covering the second metal layer.