Organic Electroluminescent Device Emission-Auxiliary Layer Charge Balance
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Solution Overview
Problem
Current organic electroluminescent devices face challenges in achieving high efficiency and long lifetime due to charge imbalance and low color purity, primarily because of the properties of the hole transport layer and the faster hole mobility compared to electron mobility, which results in reduced efficiency and lifetime.
Innovation Solution
Incorporating a compound as an emission-auxiliary layer with a high T1 value and wide band gap to balance charge transfer between the hole transport layer and the light emitting layer, thereby optimizing energy levels and material properties to improve luminous efficiency, color purity, and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a material with fast hole mobility is used to achieve low driving voltage, then driving voltage is lowered, but charge unbalance occurs in the light emitting layer and efficiency decreases
Solution Approach 1:
An emission-auxiliary layer is introduced as an intermediary between the hole transport layer and the light emitting layer. This intermediate layer has high hole mobility to transport holes efficiently while also having a high T1 value to prevent exciton transfer to the hole transport layer, thus maintaining charge balance and preventing efficiency loss while achieving low driving voltage
2Productivity
If material with low HOMO value is used in hole transport layer to achieve good hole transport, then hole transport is improved, but T1 value is low causing exciton transfer to hole transport layer and color purity reduction
Solution Approach 1:
The emission-auxiliary layer serves as a mediator with high T1 value that blocks exciton transfer to the hole transport layer while allowing hole transport. This resolves the conflict between achieving good hole transport (low HOMO) and maintaining color purity by preventing exciton leakage to the hole transport layer
Solution Approach 2:
Different layers are assigned different local properties: the hole transport layer has low HOMO for efficient hole transport, while the emission-auxiliary layer has high T1 for exciton blocking. Each layer performs its specific function optimally without interfering with the other's performance
3Manufacturing precision
If emission-auxiliary layer material has high T1 value and wide band gap to prevent exciton transfer, then color purity and efficiency are improved, but driving voltage may increase
Solution Approach 1:
The emission-auxiliary layer material is designed with specific parameter combinations: high T1 value (for exciton blocking) combined with high hole mobility (for efficient hole transport). This parameter optimization allows the layer to prevent exciton transfer while maintaining low driving voltage through efficient charge transport
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 use of the compound as an emission-auxiliary layer significantly lowers the driving voltage and enhances luminous efficiency, color purity, and lifetime of the organic electroluminescent device by optimizing charge balance and material properties.
Implementation Method 1
material having a hole mobility, a high T1 (electron block) value, and a wide band gap
Implementation Method 2
an organic light emitting phenomenon refers to a phenomenon in which electric energy is converted into light energy of an organic material
Data Source
AI summary
The organic electric element comprising a compound represented by Formula 1 as material of an emission-auxiliary layer and an electronic device thereof are disclosed, and by comprising the compound represented by Formula 1 in an emission-auxiliary layer, the driving voltage of the organic electric element can be lowered, and the luminous efficiency and life time of the organic electric element can be improved.