Transparent Cathode OLED with N-Doped Electron Transport Layer
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Solution Overview
Problem
In the manufacturing of both-side emission organic light emitting diodes, it is challenging to use conductive oxide films with high work functions as cathodes due to difficulties in electron injection, leading to increased operation voltage and reduced light emission efficiency.
Innovation Solution
An organic light emitting diode with an inverted structure is developed, where a transparent cathode made of high work function metal oxide is used, and an n-type doped electron transport layer is introduced between the cathode and the light emitting layer to facilitate electron injection, allowing for the use of the transparent electrode as both the cathode and anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conductive oxide film with high work function is used as a cathode in an inverted structure OLED, then the transparent electrode can be used as both anode and cathode, but electron injection becomes difficult and operation voltage increases
Solution Approach 1:
An electron injection layer is introduced as an intermediary between the transparent cathode (conductive oxide film) and the organic material layer. This intermediate layer has a lower work function than the transparent electrode, facilitating electron injection while allowing the transparent electrode to maintain its dual-function capability as both anode and cathode.
Solution Approach 2:
The work function parameter of the electrode interface is modified by introducing the electron injection layer with different material properties. This changes the energy level alignment between the transparent cathode and the organic layer, enabling efficient electron injection despite the high work function of the transparent electrode material.
2Device complexity
If a conductive oxide film with high work function is used as a cathode, then the structure is simplified, but light emission efficiency deteriorates
Solution Approach 1:
The electron injection layer serves as a mediator that resolves the conflict between structural simplicity and emission efficiency. While the overall inverted structure remains relatively simple, this thin intermediate layer enables efficient electron injection, preventing energy loss and maintaining high light emission efficiency.
3Illumination intensity
If a conductive oxide film with high work function is used as a cathode, then transparency is maintained, but operation voltage is largely increased
Solution Approach 1:
The electron injection layer acts as an intermediary that reduces the energy barrier for electron injection. This allows the transparent conductive oxide film to maintain its transparency while the intermediate layer compensates for the high work function, keeping operation voltage at acceptable levels.
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 enables efficient electron injection and emission in both directions, improving light emission efficiency and reducing the operation voltage, while maintaining transparency for both-side emission capabilities.
Implementation Method 1
an n-type doped electron transport layer which includes an electron transport material and an n-type dopant
Implementation Method 2
a photon corresponding to an energy difference is emitted while the exciton falls to the base state
Data Source
AI summary
The present invention provides an organic light emitting diode comprising a substrate; a transparent cathode; an anode; and an organic material layer interposed between the transparent cathode and the anode, wherein the organic material layer comprises a light emitting layer and an n-type doped electron transport layer, the n-type doped electron transport layer includes an electron transport material and an n-type dopant and is disposed between the transparent cathode and the light emitting layer, and a method for manufacturing the same.