Matching Layers for Phosphorescent OLED Charge Injection
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Solution Overview
Problem
Phosphorescent OLEDs face inefficiencies in electron and hole injection due to materials with low conductivities and exciton quenching characteristics, which affect the overall performance of the device.
Innovation Solution
Incorporating matching layers with energy levels similar to the phosphorescent organic material on both sides of the light emitting layer, and conditioning the surface of organic layers with organic moieties to facilitate efficient hole and electron transport and injection, thereby optimizing the recombination zone and charge balance within the light emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent emitters are used to achieve emission from both singlet and triplet excited states, then light emission efficiency is improved, but device performance deteriorates due to low conductivity materials and exciton quenching characteristics
Solution Approach 1:
The patent introduces matching layers as intermediary components between the electrodes and the phosphorescent emitting layer. These matching layers have energy levels (HOMO and LUMO) that are matched to the phosphorescent material, serving as a bridge to facilitate efficient charge injection. This intermediary structure resolves the contradiction by enabling high efficiency emission while maintaining reliable device performance through improved charge transport.
Solution Approach 2:
The patent modifies the energy level parameters of the organic layers by incorporating matching materials with specific HOMO and LUMO levels that match the phosphorescent emitter. This parameter matching changes the electrical characteristics of the device, improving both charge injection efficiency and overall device performance while maintaining high light emission efficiency.
2Reliability
If multiple organic layers are added to optimize charge confinement and transport functions, then device performance is improved, but production cost increases
Solution Approach 1:
The matching layers serve multiple functions simultaneously: they act as charge injection layers, charge transport layers, and energy level matching layers. This multi-functionality reduces the need for separate specialized layers, simplifying the device structure and reducing production costs while maintaining optimized charge confinement and transport performance.
Solution Approach 2:
The patent combines the functions of charge injection, charge transport, and energy level matching into integrated matching layers. By merging these functions into fewer layers rather than using separate layers for each function, the device structure is simplified, reducing manufacturing complexity and cost while maintaining high 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 enhances the external quantum efficiency and power efficiency of OLEDs by enabling direct injection of charges and expanding the recombination zone, leading to improved light emission and extended device lifetime.
Implementation Method 1
a light emitting layer including a phosphorescent organic material
Data Source
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AI summary
Techniques are described for forming an organic light emitting diode device with improved device efficiency. Materials having at least one energy level that is similar to those of a phosphorescent light emitting material in the diode are incorporated into the device to directly inject holes or electrons to the light emitting material.