Dual-Cathode OLED Structure for Electron Injection and Light Transparency
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in improving light emitting efficiency and preventing damage to the organic light emitting layer due to the limitations of cathode materials, particularly with regards to electrical resistance and light transparency.
Innovation Solution
The implementation of a dual-cathode structure, where the first cathode includes a metal and the second cathode is made of transparent conductive oxide, both electrically connected to an auxiliary line, enhances electron injection properties while maintaining light transparency and reducing electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single cathode made of metal is used, then electrical resistance is reduced and electron injection is improved, but light transparency is compromised
Solution Approach 1:
The cathode is divided into two separate layers: a first cathode made of metal for electron injection and a second cathode made of transparent conductive oxide for light transparency. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
The dual-cathode structure combines two different materials (metal and transparent conductive oxide) into a composite cathode system. The metal layer provides electrical conductivity and electron injection, while the transparent conductive oxide layer maintains light transparency, creating a composite structure that achieves both properties simultaneously.
2Illumination intensity
If a single cathode made of transparent conductive oxide is used, then light transparency is maintained, but electrical resistance increases and electron injection deteriorates
Solution Approach 1:
The cathode is segmented into two functional layers where the metal layer specifically handles electron injection while the transparent conductive oxide layer maintains light transparency. This division of labor resolves the contradiction by assigning each material to its strength.
Solution Approach 2:
The composite cathode structure combines metal and transparent conductive oxide in a layered configuration, where the metal provides low electrical resistance and the transparent conductive oxide provides high light transparency, achieving both properties that neither material could provide alone.
3Reliability
If metal cathode material is deposited directly on the organic light emitting layer, then electrical connection is achieved, but sputtered particles damage the organic light emitting layer
Solution Approach 1:
The first cathode made of metal acts as an intermediary layer between the organic light emitting layer and the second transparent cathode. It provides the electrical connection and electron injection function while being positioned to minimize direct sputtering damage to the organic layer, and the second transparent cathode completes the electrical connection without requiring direct metal contact with the organic material.
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 improves light emitting efficiency by optimizing electron injection and prevents damage to the organic light emitting layer from sputtered particles, ensuring stable connections and enhanced display quality.
Implementation Method 1
a first cathode including a metal and thereby electrically connected to the auxiliary line, wherein the first cathode is on the organic light emitting layer
Implementation Method 2
a second cathode including a transparent oxide and thereby electrically connected to the first cathode
Implementation Method 3
holes and electrons provided to the organic light emitting layer are recombined to generate excitons, and light is generated from the organic light emitting layer by energy which is generated as the states of the excitons are changed from ground states to excited states
Data Source
AI summary
An organic light emitting device includes a base substrate having a pixel region and a non-pixel region, an organic light emitting element on the pixel region, and an auxiliary line in the non-pixel region. The organic light emitting element includes an anode, a first organic light emitting layer disposed on the anode, a first cathode, and a second cathode. The first cathode is on the first organic light emitting layer to be thereby electrically connected to the auxiliary line. The second cathode is on the first cathode to be thereby electrically connected to the first cathode. The first cathode may include a metal and the second cathode may include a transparent conductive oxide (TCO).