Single-Layer Internal Electrode for Stacked OLED Efficiency
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Solution Overview
Problem
Conventional stacked organic light emitting devices with two-layered internal electrodes face challenges in effective formation due to poor physical bonding and damage risks during the sputtering process, leading to stability and cost issues.
Innovation Solution
A stacked organic light emitting device with a single-layered internal electrode made from metals or metal oxides with a work function below 4.5 eV, where an organic material layer with an electron affinity above 4 eV acts as both an anode and hole injection layer, allowing for easier fabrication and improved electron injection without the need for a separate internal anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-layered internal electrode structure is used in stacked organic light emitting devices, then the device can provide separate anode and cathode functions, but the physical bonding between layers is poor and the sputtering process causes damage risks
Solution Approach 1:
The patent combines the anode and hole injection layer into a single integrated layer structure. The internal electrode is formed as a unified layer that simultaneously provides both anode functionality and hole injection capability, eliminating the need for separate layers and improving physical bonding while reducing fabrication complexity
Solution Approach 2:
The internal electrode layer is designed to perform multiple functions simultaneously: it serves as the anode for electron-hole recombination and as the hole injection layer for charge carrier injection. This multi-functional design reduces the number of required layers and simplifies the overall device structure
2Illumination intensity
If higher current density is applied to increase brightness, then the brightness of the organic light emitting device improves, but the stability of the organic material layer and thin film structure degrades
Solution Approach 1:
The patent optimizes the work function parameter of the internal electrode material to below 4.5 eV, which improves hole injection efficiency and allows for lower operating current densities. This parameter optimization enables the device to achieve high brightness while maintaining stability by reducing the stress on the organic material layer
3Ease of manufacture
If a single-layered internal electrode with work function below 4.5 eV is used, then the fabrication process is simplified and electron injection is improved, but the device must rely on organic material layer properties to achieve both anode and hole injection functions
Solution Approach 1:
The patent specifies precise work function parameter requirements for the internal electrode material (below 4.5 eV) and the organic material layer (electron affinity above 4 eV). By controlling these key parameters, the single-layered structure can achieve both anode and hole injection functions without requiring complex multi-layer configurations
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 light emitting efficiency and brightness while reducing manufacturing costs and preventing device damage, as the single-layered internal electrode can be formed through thermal evaporation, improving the stability and efficiency of the organic light emitting device.
Implementation Method 1
the single-layered internal electrode can be formed through thermal evaporation
Implementation Method 2
holes and electrons generated from the anode and cathode are injected into the organic material layer so that the holes are combined with the electrons in the organic material layer, thereby generating excitons. When the excitons have become the ground state, light is generated
Data Source
AI summary
Disclosed is a stacked organic light emitting device and a display apparatus including the stacked organic light emitting device. The stacked organic light emitting device includes an anode connected to an external power source, a cathode connected to the external power source, at least two light emitting sections aligned between the anode and the cathode, including a light emitting layer, and an internal electrode aligned between the light emitting sections. The internal electrode is a single-layered internal electrode which is made from one selected from the group consisting of a metal, alloys of the metal, and metal oxides thereof, having a work function below 4.5 eV, each light emitting section includes an organic material layer containing an organic material having an electron affinity above 4 eV, and the organic material layer is formed between the light emitting layer of the light emitting section and the electrode facing the anode connected to the external power source in two electrodes which make contact with the light emitting section.