Organic Electroluminescence Display Sputtering Damage Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Top-emission organic electroluminescence display devices face issues with damage from electrons, ions, and active oxygen during sputtering, leading to increased light-emission voltage and reduced electric current-luminance efficiency, particularly when the lower electrode is formed by aluminum, resulting in burn-in and color irregularities.
Innovation Solution
A four-layer structure for the organic electroluminescence element is introduced, comprising a first layer with electron transport and electron-donating properties, a second layer with hole transport properties, a third layer containing a light-emitting substance, and a fourth layer with electron transport properties, along with additional layers containing elements from the periodic table to enhance electron injection and hole injection, and using transparent conductive substances for electrodes to stabilize the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent electrode is formed by sputtering on the organic electroluminescence layer, then the electrode can be formed with good electrical conductivity, but the organic electroluminescence layer is damaged by electrons, ions, and active oxygen during sputtering
Solution Approach 1:
An electron injection layer is introduced as an intermediary between the transparent electrode and the organic electroluminescence layer. This layer receives the harmful electrons, ions, and active oxygen generated during sputtering, protecting the organic electroluminescence layer from damage while still allowing the transparent electrode to form with good electrical conductivity.
Solution Approach 2:
The electron injection layer is formed in advance before the transparent electrode is deposited by sputtering. This preliminary action creates a protective barrier that prevents damage to the organic electroluminescence layer during the subsequent sputtering process, enabling reliable electrode formation without compromising the organic layer.
2Reliability
If alkali metal is contained in the electron transport layer and light-emitting layer, then electron injection is improved, but the layered structure between anode and hole transport layer is not optimized
Solution Approach 1:
The device is segmented into distinct functional layers with specific dopant assignments: the electron transport layer contains alkali metal for electron injection, while the hole transport layer contains alkaline-earth metal for hole injection. This segmentation optimizes each layer's function and completes the overall layered structure.
Solution Approach 2:
Different regions of the device are given different chemical compositions: the electron transport layer is doped with alkali metal to enhance electron injection, while the hole transport layer is doped with alkaline-earth metal to enhance hole injection. This local quality optimization improves overall device performance.
3Reliability
If the lower electrode is formed by aluminum, then electron injection is enhanced, but burn-in and color irregularities occur
Solution Approach 1:
The electron injection layer acts as a mediator between the aluminum lower electrode and the organic electroluminescence layer. It receives electrons from the aluminum electrode and injects them into the organic layer in a controlled manner, preventing direct harmful interactions that cause burn-in and color irregularities while maintaining efficient electron injection.
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 achieves stable hole injection, reduces image pattern burn-in, and improves color reproducibility by adjusting the tint of emitted light through the interference effect, while maintaining long-term reliability and efficient luminance.
Implementation Method 1
an organic electroluminescence layer (also called an organic multilayer film) that emits light by the application of an electric field
Implementation Method 2
application of an electric field between the two electrodes in which, e.g., a transparent electrode is an anode and a reflective metallic electrode is a cathode
Implementation Method 3
the transparent electrode formed on an organic electroluminescence layer is formed by sputtering
Data Source
AI summary
The invention provides an organic electroluminescence display device that makes it possible to obtain a highly reliable display. The organic electroluminescence display device has an organic electroluminescence element that includes a first layer (3) that contains a first substance that exhibits electron transport properties, and a second substance that exhibits electron-donating properties with respect to the first substance; a second layer (4) that is composed of a third substance that exhibits hole transport properties; a third layer (light-emitting layer (5) that contains a light-emitting substance; and a fourth layer (6) that is formed from a substance that exhibits electron transport properties.