Polymer Light Emitting Element with Three-Layer Cathode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic light emitting elements with a cathode composed of three oxide thin film layers suffer from low light emitting efficiency due to the smaller aperture size required for bottom emission types, limiting the light emitting surface and efficiency.
Innovation Solution
A polymer light emitting element with a first electrode near the substrate and a counter electrode composed of three layers, where at least one material in the second layer has a reducing action on materials in the first layer, and the third layer has visible light transmittance of 40% or more, enhancing light emitting efficiency and surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a bottom emission type element is made with a drive circuit present, then the light emitting aperture becomes smaller, but the light emitting efficiency decreases
Solution Approach 1:
The patent inverts the emission direction from bottom emission to top emission. The organic light emitting element is designed to emit light from the top surface through a transparent electrode, allowing the drive circuit to be positioned at the bottom without blocking the light output. This inversion resolves the contradiction by enabling both a large light emitting aperture and high light emitting efficiency to coexist.
2Device complexity
If a three-layer cathode structure is used with oxide thin films, then the electrode complexity increases, but the light emitting efficiency remains low
Solution Approach 1:
The patent changes the material parameters of the cathode layers. Instead of using conventional oxide thin films, the invention employs specific organic compounds with optimized HOMO and LUMO energy levels. The cathode consists of three layers with specific functions: electron injection layer, electron transport layer, and hole blocking layer, each composed of organic materials with tailored electronic properties to achieve high efficiency while maintaining manageable structural complexity.
3Area of moving object
If the light emitting surface is increased for top emission type elements, then the aperture size increases, but the manufacturing difficulty increases
Solution Approach 1:
The patent segments the device into distinct functional layers with clear interfaces. The top emission structure is divided into: substrate, drive circuit layer, organic light emitting layer, transparent electrode, and encapsulation layers. Each layer can be independently optimized and manufactured, facilitating large-area production while maintaining high light emitting efficiency and simplifying the overall manufacturing process.
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 results in a polymer light emitting element with a large light emitting surface and high efficiency, enabling a longer brightness half-life and easier manufacturing of top emission type display devices.
Implementation Method 1
at least one material contained in the second layer has a reducing action on at least one material contained in the first layer
Implementation Method 2
a light emitting layer provided between the first electrode and the second electrode and containing a polymer compound
Data Source
AI summary
A polymer light emitting element having a large light releasing surface, a high light emitting efficiency and a long life, a polymer light emitting display device and planar light source, as well as a method for manufacturing the polymer light emitting element are provided. The polymer light emitting element is characterized by comprising a first electrode, a second electrode and a light emitting layer provided between the first electrode and the second electrode and containing a polymer compound, wherein the second electrode is composed of three layers, a first layer, a second layer and a third layer arranged in this order viewed from the light emitting layer, and at least one of materials contained in the second layer has a reducing action on at least one of materials contained in the first layer, and the visible light transmittance of the third layer is 40% or more.