Phosphorescent Organic EL Device Halogen Impurity Control
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Solution Overview
Problem
Phosphorescent organic electroluminescent devices face challenges with halogen impurities, which reduce emission luminance, luminous efficiency, and lifespan due to exciton quenching, and existing analysis methods are limited in sensitivity and accuracy for detecting low concentrations of these impurities.
Innovation Solution
The use of inductively coupled plasma-mass spectrometry (ICP-MS) and coulometric titration methods to quantify halogen element concentrations, specifically bromine, iodine, and chlorine, in the host material and phosphorescent organic metal complex, ensuring concentrations are reduced to 50 ppm or less, thereby enhancing emission luminance and extending the device's half-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phosphorescent organic electroluminescent devices are operated, then light emission is achieved, but halogen impurities cause exciton quenching that reduces emission luminance, luminous efficiency, and lifespan
Solution Approach 1:
The patent extracts and removes halogen impurities (bromine, iodine, chlorine) from the phosphorescent organic metal complex and host material through purification processes. By taking out these harmful impurities and reducing their concentration to 50 ppm or less, the exciton quenching effect is minimized, thereby improving luminous efficiency and emission luminance while extending device lifespan.
2Measurement precision
If conventional analysis methods are used to detect halogen impurities, then analysis is performed, but sensitivity and accuracy are insufficient for detecting low concentrations of impurities
Solution Approach 1:
The patent replaces conventional analysis methods with inductively coupled plasma-mass spectrometry (ICP-MS), which provides significantly higher sensitivity and accuracy for detecting halogen impurities at low concentrations (50 ppm or less). This substitution enables precise measurement of bromine, iodine, and chlorine concentrations, allowing for effective quality control and optimization of device performance.
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 approach significantly improves the luminous efficiency and extends the lifespan of phosphorescent organic electroluminescent devices by minimizing halogen impurities, leading to higher emission luminance and longer operational stability.
Implementation Method 1
it is proposed as well to make use of an organic phosphorescent material in addition to a luminescent material for a light-emitting layer in an organic EL device
Implementation Method 2
the halogen element mass concentrations of bromine, iodine and chlorine as impurities are identified respectively by inductively coupled plasma-mass spectrometry (ICP-MS analysis)
Data Source
AI summary
Provided is an organic electroluminescent device in which an organic thin film layer comprising a single layer or plural layers comprising a phosphorescence light-emitting layer containing at least a host material and a phosphorescent organic metal complex is interposed between a cathode and an anode, wherein the total of the halogen element mass concentrations of bromine, iodine and chlorine which are contained as impurities in the host material constituting the light-emitting layer described above is 50 ppm or less. It has a high emission luminance, a high luminous efficiency and a long life.