Electron-Injection Layer Alkali Metal Reducing Agent EL Device
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Solution Overview
Problem
Current light-emitting devices face challenges in achieving high emission efficiency and low power consumption, particularly due to increased carrier injection barriers at interfaces during manufacturing, which can lead to higher driving voltages and decreased emission efficiency.
Innovation Solution
Incorporating an electron-injection layer with a mixed film or stacked-layer film of an alkali metal compound and a reducing agent, where the reducing agent is more than 20 vol % and less than 80 vol %, and having a work function between 2.5 eV and 4.0 eV, to facilitate ionization of the alkali metal compound and reduce carrier injection barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional electron-injection layers are used without reducing agents, then device structure is simpler, but carrier injection barriers increase and emission efficiency decreases
Solution Approach 1:
The electron-injection layer is constructed as a composite material combining an alkali metal compound (such as LiF, CsF, or Li2SiO3) with a reducing agent (such as Alq3, BCP, or TPBi). This composite structure enables the reducing agent to donate electrons to the alkali metal compound, creating a low-work-function surface that facilitates carrier injection while maintaining structural integrity and stability during device operation.
Solution Approach 2:
The invention changes the work function parameter of the electron-injection layer by introducing reducing agents with specific work functions (2.5-4.0 eV). This parameter modification creates a favorable energy level alignment between the electrode and the electron-transport layer, reducing the carrier injection barrier and improving emission efficiency without significantly complicating the device structure.
2Ease of manufacture
If the electron-injection layer is exposed to chemical solutions or etching gases during manufacturing, then manufacturing process is simpler, but carrier injection barriers increase and driving voltage increases
Solution Approach 1:
The reducing agent component in the electron-injection layer acts as a sacrificial protective layer that is intentionally designed to be consumed or modified during manufacturing processes involving chemical solutions or etching gases. This disposable protective function preserves the underlying alkali metal compound and maintains the low carrier injection barrier even after exposure to harsh manufacturing conditions.
Solution Approach 2:
The reducing agent provides beforehand cushioning protection to the electron-injection layer during manufacturing. By positioning the reducing agent in contact with the alkali metal compound before manufacturing processes begin, it creates a protective interface that prevents direct damage from chemical solutions or etching gases, thereby maintaining the low-work-function properties and carrier injection efficiency.
3Reliability
If higher driving voltages are applied to overcome carrier injection barriers, then carrier injection can be maintained, but power consumption increases
Solution Approach 1:
The invention changes the work function parameter of the electron-injection layer to 2.5-4.0 eV through the use of reducing agents, which creates a lower energy barrier for carrier injection. This parameter optimization allows carriers to be injected efficiently at lower driving voltages, thereby reducing power consumption while maintaining reliable carrier injection and high emission 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 configuration enhances carrier balance and emission efficiency while maintaining low power consumption, even when the electron-injection layer is exposed to chemical solutions or etching gases during manufacturing, preventing increases in driving voltage.
Implementation Method 1
the reducing agent is more than 20 vol % and less than 80 vol %, and having a work function between 2.5 eV and 4.0 eV, to facilitate ionization of the alkali metal compound and reduce carrier injection barriers
Data Source
AI summary
A novel light-emitting device with high emission efficiency is provided. The light-emitting device includes a first electrode, a second electrode, an EL layer, and an insulating layer. The EL layer is positioned between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, an electron-transport layer, and an electron-injection layer. The electron-transport layer is positioned over the light-emitting layer. The insulating layer is in contact with an end portion of the light-emitting layer and an end portion of the electron-transport layer. The electron-injection layer is positioned over the electron-transport layer. The electron-injection layer includes an alkali metal compound and a reducing agent.