Transparent Electrode with 12CaO.7Al2O3 Particles for OLEDs
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Solution Overview
Problem
Conventional transparent electrodes for organic light emitting devices (OLEDs) face limitations in achieving low sheet resistance, high optical transmittance, and low work function, which are essential for high light emission efficiency and image quality.
Innovation Solution
An electrode comprising a metal oxide matrix with dispersed 12CaO.7Al2O3 particles, formed through sputtering and deposition methods, which enhances electric conductivity and optical properties, thereby achieving low sheet resistance and work function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal alloy such as MgAg is used to form a transparent cathode with low resistance and low work function, then the electrical conductivity is improved, but the optical transmittance deteriorates (only about 30% even at 15 nm thickness)
Solution Approach 1:
The patent uses a composite structure consisting of a metal oxide layer (such as ITO, IZO, or ZnO) combined with a metal alloy layer (such as MgAg, MgAl, or AlAg). This composite structure allows the metal oxide to provide high optical transmittance while the metal alloy layer provides low resistance and low work function, thereby resolving the contradiction between electrical conductivity and optical transmittance
Solution Approach 2:
The patent applies different materials with different properties to different layers of the electrode structure. The metal oxide layer is optimized for optical transmittance, while the metal alloy layer is optimized for electrical conductivity and work function. This local differentiation of material properties allows each layer to excel at its specific function without compromising the overall performance
2Illumination intensity
If ITO is used as a transparent cathode material, then high optical transmittance is achieved, but the work function becomes relatively high which limits its effectiveness as a cathode
Solution Approach 1:
The patent combines metal oxide (ITO, IZO, or ZnO) with metal alloy layers (MgAg, MgAl, or AlAg) to create a composite electrode structure. The metal oxide provides high optical transmittance while the metal alloy layer provides low work function, thereby resolving the contradiction between optical transmittance and work function
3Illumination intensity
If the metal film thickness is reduced to improve optical transmittance, then transparency is enhanced, but the sheet resistance increases and electrical conductivity deteriorates
Solution Approach 1:
The patent uses a composite structure where a thin metal oxide layer (providing optical transmittance) is combined with a metal alloy layer (providing electrical conductivity). This allows the overall structure to achieve high transparency while maintaining low sheet resistance through the synergistic combination of materials
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 electrode demonstrates improved optical transmittance and low work function, enabling high light emission efficiency and internal efficiency in OLEDs, resulting in high-quality image display.
Implementation Method 1
the metal oxide and 12CaO.7Al2O3 are formed on a substrate by sputtering and deposition
Implementation Method 2
the metal oxide and 12CaO.7Al2O3 are formed on a substrate by sputtering and deposition
Data Source
AI summary
An electrode including metal oxides and a plurality of 12CaO.7Al2O3 particles, a method of preparing the electrode, an electronic device including the electrode, and, in particular, an organic light emitting device including the electrode. The electrode has low resistance, high optical transmittance, and a low work function.