Organic EL Electron Injection Region MxAOy Compound
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Solution Overview
Problem
Existing organic electroluminescence (EL) devices face challenges in achieving uniform electron injection over large areas, high luminous efficiency, and long device lifetime due to issues with electron injecting layer thickness, halogen inhibition, and electron injection barriers, leading to increased voltage requirements and reduced efficiency.
Innovation Solution
The use of a co-deposited electron injection region containing a compound represented by the formula MxAOy, where M is Li, Na, K, Rb, or Cs, and A is Zr, V, Nb, Ta, Si, or Ge, along with an oxide of a transition metal, a nitrogen-containing heterocyclic derivative, and a chalcogenide, to enhance electron injection efficiency and luminous efficiency at low voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an extremely thin alkali metal oxide or alkali metal halide layer is used in the electron injecting layer to improve electron injection efficiency, then electron injection efficiency is improved, but it is difficult to make the layer thin in a uniform fashion over a large area, leading to variations in device characteristics
Solution Approach 1:
The invention changes the material composition parameters by introducing specific compounds (formula 1) with controlled stoichiometric ratios and combining multiple materials in the electron injecting layer, achieving uniform thickness and composition that enables consistent electron injection efficiency across large areas
Solution Approach 2:
The invention uses composite materials in the electron injecting layer by combining alkali metal compounds (formula 1) with other functional materials, creating a multi-component system that simultaneously achieves uniform deposition, low work function, and high electron injection efficiency
2Manufacturing precision
If the thickness of the electron injecting layer is increased to improve uniformity, then manufacturing uniformity is improved, but the voltage at which the device is driven is raised
Solution Approach 1:
The invention changes the material composition parameters by introducing specific compounds (formula 1) with controlled stoichiometric ratios and combining multiple materials in the electron injecting layer, achieving uniform thickness and composition that enables consistent electron injection efficiency across large areas
Solution Approach 2:
The invention uses a standardised layer structure and material composition that can be consistently replicated across large areas, ensuring uniform device characteristics without requiring excessive thickness
3Reliability
If a co-deposited layer of transition metal oxide and alkali metal halide is used to improve electron injection, then electron injection efficiency is improved, but halogen in the electron injecting layer threatens to inhibit electron injection or reduce device lifetime
Solution Approach 1:
The invention extracts and removes harmful halogen elements from the electron injecting layer composition, replacing them with alternative compounds (formula 1) that provide electron injection functionality without the detrimental effects of halogen
Solution Approach 2:
The invention converts the potentially harmful interaction between halogen and electron injection into a beneficial effect by using compounds (formula 1) that achieve low work function and high electron injection efficiency without halogen, thereby eliminating the harmful inhibition while maintaining the desired performance
4Reliability
If an electron injecting layer containing alkali metal is used to improve electron injection, then electron injection efficiency is improved, but the saturated vapor pressure of the alkali metal is so high that the metal may be liberated in a chamber to serve as a contaminant
Solution Approach 1:
The invention uses composite materials in the electron injecting layer by combining alkali metal compounds (formula 1) with other functional materials, creating a multi-component system that simultaneously achieves uniform deposition, low work function, and high electron injection efficiency
Solution Approach 2:
The invention uses compounds (formula 1) that are stable and non-volatile under deposition conditions, replacing reactive alkali metals that would otherwise be liberated as contaminants in the vacuum chamber
5Reliability
If a laminated structure of transition metal oxide layer and alkali metal layer is used to provide the electron injecting layer, then electron injection efficiency is improved, but an electron injection barrier between the electron transporting layer and the transition metal oxide layer is large and hence the efficiency with which an electron is injected from the cathode layer to the light emitting layer is insufficient
Solution Approach 1:
The invention merges the functions of multiple layers into a single integrated electron injecting layer containing compounds (formula 1), eliminating the interface barrier between separate transition metal oxide and alkali metal layers while maintaining the beneficial electron injection properties
Solution Approach 2:
The invention uses composite materials in the electron injecting layer by combining alkali metal compounds (formula 1) with other functional materials, creating a multi-component system that simultaneously achieves uniform deposition, low work function, and high electron injection efficiency
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 approach results in a thermally and chemically stable organic EL device with improved electron injection efficiency, high luminous efficiency at low voltage, and extended device lifetime, while preventing sputtering damage and maintaining low driving voltage.
Implementation Method 1
high efficiency with which an electron is injected from a cathode layer or an intermediate conductive layer to a light emitting layer
Implementation Method 2
An organic electroluminescence device (hereinafter, 'electroluminescence' may be abbreviated as 'EL') is a spontaneous light emitting device which utilizes the principle that a fluorescent substance emits light by energy of recombination of holes injected from an anode layer and electrons injected from a cathode layer when an electric field is applied
Data Source
AI summary
Provided is an organic electroluminescence device that has solved the conventional problems, and is thermally and chemically stable, has high efficiency with which an electron is injected from a cathode layer or an intermediate conductive layer to a light emitting layer, provides high luminous efficiency at a low voltage, and can maintain a long lifetime. Specifically, the organic electroluminescence device is an organic electroluminescence device, including: two electrode layers and optionally one or more intermediate conductive layers; a light emitting layer between the electrode layers, or between one of the electrode layers and the intermediate conductive layer and/or between the intermediate conductive layers; and an electron injection region formed of one or two or more layers between the light emitting layer and the cathode layer and/or between the light emitting layer and the intermediate conductive layer, in which at least one layer in the electron injection region contains at least one kind selected from the group consisting of an oxide of a transition metal belonging to any one of Groups 5 to 8 of the periodic table, a nitrogen-containing heterocyclic derivative, and a chalcogenide, and further contains a compound represented by the formula: MxAOy (in the formula, M represents Li, Na, K, Rb, or Cs, A represents Zr, V, Nb, Ta, Si, or Ge, x represents 1 or 2, and y represents an integer of 1 to 4).