Electric Field Quenching in Phosphorescent OLEDs
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Solution Overview
Problem
Current OLED technologies face challenges in achieving substantial electric-field-induced quenching of photoluminescence, with existing materials and devices not effectively suppressing photoluminescence to a high degree, limiting their efficiency and application in display technologies.
Innovation Solution
The use of an electric field quenching device with an active layer comprising an organic phosphorescent emitter compound and a charge transporting host compound, where the phosphorescent emitter compound is an organometallic complex with specific metal and ligand configurations, allows for significant photoluminescence quenching when a voltage is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional photoluminescent materials are used in OLEDs, then the device structure can be simplified, but the photoluminescence cannot be substantially quenched by electric field
Solution Approach 1:
The patent changes the fundamental parameter of the photoluminescent material from conventional fluorescent emitters to phosphorescent emitter compounds. This parameter change enables substantial photoluminescence quenching (>50% suppression) when voltage is applied, while maintaining a simplified device structure without requiring additional quenching layers or complex configurations.
Solution Approach 2:
The patent employs composite material strategy by combining phosphorescent emitter compounds with charge transporting host compounds in the active layer. This composite approach creates a system where the phosphorescent emitter provides high photoluminescence efficiency and the charge transporting host enables effective charge carrier injection and transport, achieving both structural simplicity and high quenching efficiency.
2Adaptability or versatility
If conventional fluorescent emitter compounds are used, then the device can operate with standard materials, but photoluminescence suppression exceeds only a limited degree
Solution Approach 1:
The patent changes the emission mechanism parameter from fluorescent to phosphorescent, utilizing triplet excitons and phosphorescent emission. This parameter change enables much higher photoluminescence quenching efficiency (>50% suppression) because phosphorescent materials have longer excited state lifetimes and different charge carrier interaction characteristics, allowing more effective electric field control.
Solution Approach 2:
The patent adapts the device structure from conventional fluorescent OLEDs by copying the basic architecture (substrate, electrodes, active layer) and simply replacing the fluorescent emitter with a phosphorescent emitter compound. This copying approach maintains material compatibility and device structure while achieving superior photoluminescence quenching performance.
3Ease of operation
If voltage is applied to quench photoluminescence, then display switching is enabled, but incomplete quenching reduces display contrast and efficiency
Solution Approach 1:
The patent changes the photoluminescent material parameter to phosphorescent emitter compounds, which exhibit much stronger electric field dependence of photoluminescence. This enables complete quenching (>50% suppression, preferably >90%) when voltage is applied, achieving excellent display contrast and efficiency with clear on/off switching capability.
Solution Approach 2:
The patent replaces the need for mechanical or complex electrical control systems with a simple voltage application approach. By using phosphorescent emitter compounds that naturally respond to electric fields with strong photoluminescence quenching, the system achieves efficient display switching through simple voltage control without requiring additional control mechanisms.
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 achieves a high degree of photoluminescence quenching, with over 90% suppression of photoluminescence under applied voltage, enhancing the efficiency and versatility of OLED technologies.
Implementation Method 1
an active layer which comprises an organic phosphorescent emitter compound and a charge transporting host compound
Implementation Method 2
Field quenching of photoluminescence (hereafter FQPL) is an effect that photoluminescence decreases under an electric field, e.g. if a voltage is applied
Data Source
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AI summary
The present invention relates to electric field quenching devices (FQD) comprising at least two electrodes (101,102) and an active layer (104) in between the said at least two electrodes, characterized in that the active layer comprises at least one phosphorescent emitter compound and a charge transporting host compound. Furthermore, the present invention relates to a display comprising at least one of the electric field quenching devices according to the invention and a process for controlling and/or regulating photoluminescence.