Organic Electroluminescent Layer Structure for Stable Voltage
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving improved operating voltage, stability over time, and current efficiency.
Innovation Solution
The organic electroluminescent device incorporates a p-type charge generation layer and an organic semiconductor layer with specific compounds, including a compound of formula (I) and (II), arranged between light-emitting units to enhance charge generation and transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic electroluminescent device structure is used, then device simplicity is maintained, but operating voltage stability and current efficiency are insufficient
Solution Approach 1:
The device is segmented into multiple light-emitting units (first, second, third light-emitting units) with charge generation layers positioned between them. This segmentation allows independent optimization of each unit's charge generation while maintaining overall device functionality, thereby improving operating voltage stability without requiring complete structural redesign.
Solution Approach 2:
Charge generation layers are introduced as intermediary components between the light-emitting units. These layers mediate charge transfer and balance between adjacent light-emitting units, improving current efficiency and operating voltage stability. The intermediary layers enable controlled charge generation without directly modifying the light-emitting materials themselves.
2Productivity
If conventional charge generation is used, then device structure is simple, but current efficiency is insufficient
Solution Approach 1:
Different charge generation layers are positioned at specific locations between light-emitting units, with each layer having optimized properties for its local position. The first charge generation layer is between the first and second light-emitting units, the second charge generation layer is between the second and third light-emitting units, enabling localized optimization of charge generation to improve overall current efficiency.
3Illumination intensity
If operating voltage is increased to improve brightness, then brightness is improved, but operating voltage stability over time deteriorates
Solution Approach 1:
The charge generation layers provide feedback control for charge balance between light-emitting units. By monitoring and adjusting charge generation at the interfaces between units, the system maintains stable operating voltage over time while sustaining high brightness output. The distributed charge generation layers act as feedback points to prevent voltage drift.
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 results in superior operating voltage stability and current efficiency, surpassing the performance of conventional devices.
Implementation Method 1
When a voltage is applied to the anode and the cathode, holes injected from the anode move to the EML, via the HTL, and electrons injected from the cathode move to the EML, via the ETL
Implementation Method 2
The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted
Data Source
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AI summary
The present invention relates to an electroluminescent device comprising a compound of formula (I) and a compound of formula (II), and a display device comprising the organic electroluminescent device.