Tandem Light-Emitting Element Crosstalk Suppression
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Solution Overview
Problem
Tandem light-emitting elements used in high-definition displays face issues with crosstalk due to high conductivity in charge generation layers, leading to increased power consumption and reduced heat resistance, making it difficult to achieve high-quality images with low power consumption and heat resistance.
Innovation Solution
Incorporating 2,9-bis(naphthalen-2-yl)-4,7-diphenanthroline (NBPhen) in the charge generation layer contact with the anode side and using a charge generation layer with an electron-injection buffer region containing alkali metals like lithium, along with an electron-relay region to manage electron injection and prevent interaction, thereby reducing crosstalk and enhancing heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge generation layer with high conductivity is used to improve electron injection, then electron injection efficiency is improved, but crosstalk increases and heat resistance decreases
Solution Approach 1:
The charge generation layer is divided into two distinct regions: an electron-injection buffer region containing alkali metals (Li, Na, K, Rb, or Cs) for efficient electron injection, and a charge generation region containing a hole-transport material and electron acceptor. This segmentation allows the electron-injection buffer region to be positioned away from pixel boundaries, reducing crosstalk while maintaining high electron injection efficiency in the charge generation region.
Solution Approach 2:
The electron-injection buffer region acts as an intermediary layer between the anode and the charge generation region. It facilitates electron injection into the charge generation region while preventing direct contact between the highly conductive charge generation layer and adjacent pixels, thereby reducing crosstalk. The buffer region mediates between the need for high conductivity and the need to prevent harmful lateral current flow.
2Reliability
If a charge generation layer with high conductivity is used to improve electron injection, then electron injection efficiency is improved, but heat resistance decreases
Solution Approach 1:
By segmenting the charge generation layer into an electron-injection buffer region and a charge generation region, the patent localizes the high-conductivity material (alkali metals) to a specific region away from pixel boundaries. This reduces overall heat generation and improves heat resistance while maintaining efficient electron injection in the charge generation region where it is most needed.
Solution Approach 2:
The patent applies local quality by giving different regions of the charge generation layer different properties: the electron-injection buffer region contains alkali metals for efficient electron injection, while the charge generation region contains the hole-transport material and electron acceptor for charge separation. This localized differentiation allows high electron injection efficiency where needed while reducing overall heat generation and improving heat resistance.
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 effectively suppresses crosstalk, enables high-quality image display with low power consumption, and improves the heat resistance of the light-emitting elements, making them suitable for high-definition displays.
Implementation Method 1
a layer in contact with the anode side of the charge generation layer contains 2,9-bis(naphthalen-2-yl)-4,7-diphenanthroline (NBPhen)... using a charge generation layer with an electron-injection buffer region containing alkali metals like lithium
Implementation Method 2
a light-emitting element which includes a light-emitting layer containing an organic compound between a pair of electrodes... emits light when the light-emitting substance contained in the EL layer is excited by current flowing through the EL layer
Data Source
AI summary
A tandem light-emitting element in which generation of crosstalk can be suppressed even when the element is applied to a high-definition display is provided. In the tandem light-emitting element, a layer in contact the anode side of an intermediate layer contains 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen).