Amorphous C12A7 Electride Electron Injection Layer for OLED Stability
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Solution Overview
Problem
Conventional organic electroluminescence elements face challenges with lithium fluoride electron injection layers due to their insulating nature, requiring thin films that are difficult to form and prone to degradation, leading to issues with conductivity and stability, which affects light emitting characteristics and reliability.
Innovation Solution
The use of an amorphous C12A7 electride as the electron injection layer, which provides good electrical conductivity, stability, and a reduced electron injection barrier, allowing for thicker films and improved handling, along with a method of fabricating this layer by sputtering under low oxygen partial pressure using a crystalline C12A7 electride target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium fluoride is used in the electron injection layer, then the material provides insulating properties, but the layer thickness must be extremely thin (0.1 nm to 0.4 nm) which is difficult to form and control
Solution Approach 1:
The patent changes the material parameter from insulating lithium fluoride to conductive C12A7 electride, which fundamentally alters the electrical properties of the electron injection layer. This allows the film thickness to be increased from extremely thin (0.1-0.4 nm) to a more manufacturable range while maintaining adequate conductivity and electron injection performance
Solution Approach 2:
The patent employs C12A7 electride as a composite material that combines the benefits of insulating behavior (preventing unwanted charge leakage) with conductive properties (enabling electron injection) in a single material system, eliminating the need for extremely thin films
2Ease of manufacture
If lithium fluoride is used in the electron injection layer, then the material can be deposited, but it is unstable and prone to degradation upon contact with the atmosphere
Solution Approach 1:
The patent replaces the unstable lithium fluoride material with C12A7 electride, which offers inherent atmospheric stability. This eliminates the need for complex controlled environment handling and protective encapsulation, simplifying the manufacturing process while improving long-term device reliability
3Ease of manufacture
If the electron injection layer is made with lithium fluoride, then the material can be applied, but adequate conductivity cannot be achieved without extremely thin films
Solution Approach 1:
The patent fundamentally changes the electrical conductivity parameter of the electron injection layer by using C12A7 electride instead of lithium fluoride. The C12A7 electride maintains adequate conductivity at much thicker film levels, allowing standard deposition techniques to achieve reliable electron injection without requiring sub-nanometer precision
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 solution enhances the light emitting efficiency and reliability of organic electroluminescence elements by improving electron injection characteristics and reducing the need for precise thickness control, while maintaining stability even in atmospheric exposure.
Implementation Method 1
An electron injection layer is arranged between the light emitting layer and the cathode. The electron injection layer is made of an amorphous C12A7 electride
Implementation Method 2
forming an electron injection layer made of an amorphous electride thin film by sputtering under an atmosphere with an oxygen partial pressure of less than 0.1 Pa using a target made of a crystalline C12A7 electride
Data Source
AI summary
A light emitting device including an organic electroluminescence element is provided. The light emitting device may be a display device or a lighting device. The organic electroluminescence element includes an anode, a light emitting layer, and a cathode that are arranged in this order. An electron injection layer is arranged between the light emitting layer and the cathode. The electron injection layer is made of an amorphous C12A7 electride.