Transparent Electrode with Conducting Filaments for OLEDs
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Solution Overview
Problem
Current organic light emitting devices (OLEDs) face challenges with high driving voltage due to poor ohmic contact between transparent electrodes and organic semiconductor layers, leading to low charge injection efficiency and low light extraction efficiency, especially in the UV wavelength range.
Innovation Solution
A transparent electrode is formed using a resistance change material that transitions from a high to a low resistance state upon applying a threshold voltage, creating conducting filaments for improved conductivity and ohmic contact, and a current spreading layer using CNT or graphene is employed to prevent current concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If material with high transmittance in UV wavelength range is used, then transmittance is improved, but conductivity deteriorates due to large band gap
Solution Approach 1:
The patent modifies the electrical parameter (conductivity) of the transparent electrode material by selecting ZnO-based material with appropriate band gap characteristics. This material maintains high UV transmittance while having sufficient conductivity to function as an electrode, and forms ohmic contact with organic semiconductors, resolving the contradiction between UV transmittance and conductivity
Solution Approach 2:
The ZnO-based transparent insulating material acts as an intermediary between the organic semiconductor layer and the external circuit. It provides the necessary electrical connection (overcoming the conductivity issue) while maintaining optical transparency in UV range, and its ability to form ohmic contact further resolves the conductivity-transmittance contradiction
2Productivity
If transparent electrode with good ohmic contact is formed, then charge injection efficiency is improved, but driving voltage increases due to material limitations
Solution Approach 1:
The patent optimizes the energy level parameters of the transparent electrode by using ZnO-based material with appropriate work function. This material achieves good ohmic contact with organic semiconductors (improving charge injection efficiency) while maintaining low driving voltage through proper energy alignment, resolving the contradiction between charge injection efficiency and driving voltage
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
The solution achieves high transmittance in both UV and visible wavelength ranges while reducing driving voltage and enhancing charge injection efficiency, enabling efficient light emission across the spectrum.
Implementation Method 1
a transparent insulating material of which resistance state is changed from a high resistance state into a low resistance state according to an applied electric field
Implementation Method 2
creating conducting filaments for improved conductivity and ohmic contact
Implementation Method 3
an organic material layer which is formed on the first electrode and includes a light emitting layer
Implementation Method 4
a current spreading layer using CNT or graphene is employed to prevent current concentration
Data Source
AI summary
Provided is an organic light emitting device including a transparent electrode in which conducting filaments are formed and a method of manufacturing the same. In the organic light emitting device, a transparent electrode of an organic light emitting device is formed by using a resistance change material which has high transmittance with respect to light in a UV wavelength range and of which resistance state is to be changed from a high resistance state into a low resistance state due to conducting filaments, which current can flow through, formed in the material if a voltage exceeding a threshold voltage inherent in a material is applied to the material, so that it is possible to obtain the transparent electrode having high transmittance with respect to light in a UV wavelength range as well as light in a visible wavelength range generated by the organic light emitting device and having high conductivity.