Charge Transporting Polyester for Organic Electroluminescent Devices
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Solution Overview
Problem
Existing organic electroluminescent devices require high driving voltages and have low electron and hole carrier densities, resulting in insufficient luminance, limiting their practical application.
Innovation Solution
Incorporating a charge transporting polyester with specific repeating units in the organic compound layers between electrodes, enhancing charge injection, mobility, and luminescent characteristics, while maintaining thermal and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional organic electroluminescent devices are used, then light emission can be achieved, but high driving voltage (30V) is required and luminance is insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the charge transporting material by introducing specific repeating units with aromatic rings and heteroatoms. This structural modification optimizes charge carrier density and mobility, enabling high luminance (1000 cd/m2 or more) at low driving voltage (substantially 10V or less)
Solution Approach 2:
The patent uses a composite organic compound layer comprising multiple components: a charge transporting polyester with specific repeating units, and optionally mixed with other charge transporting materials. This composite structure synergistically improves charge injection, carrier density, and luminance efficiency
2Quantity of substance
If conventional charge transporting materials are used, then device operation is possible, but carrier density is low and recombination probability is insufficient
Solution Approach 1:
The patent modifies the molecular parameters of the charge transporting material by incorporating repeating units with specific aromatic structures and heteroatoms. This increases the material's ability to generate and transport charge carriers, achieving high carrier density and effective recombination for light emission
3Stability of the object's composition
If simple organic layers are used, then device structure is simple, but thermal stability and storage stability are insufficient
Solution Approach 1:
The patent employs a composite organic compound layer with charge transporting polyesters and other materials, creating a multifunctional system that provides both thermal stability and charge transport capability without excessive structural complexity
Solution Approach 2:
The patent introduces specific repeating units with aromatic rings and heteroatoms at strategic positions in the polymer chain. These localized structural features provide thermal stability and charge transport functionality without requiring complete structural redesign of the entire material system
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 solution enables organic electroluminescent devices to operate at lower voltages with improved luminance, stability, and reduced defects, facilitating their practical use in display devices and lighting applications.
Implementation Method 1
a light emitting material in an electroluminescent device is excited to a high energy level, and an excited light emitting substance releases, as light, extra energy produced when returned to a ground state
Implementation Method 2
Light emission by these electroluminescent devices is a phenomenon in which electrons are injected from one electrode and holes are injected from another electrode, whereby, a light emitting material in an electroluminescent device is excited to a high energy level, and an excited light emitting substance releases, as light, extra energy produced when returned to a ground state
Data Source
AI summary
An organic electroluminescent device having a pair of electrodes including a positive electrode and a negative electrode at least one of which is transparent or translucent, and one or more organic compound layers interposed between the pair of electrodes, at least one layer of the organic compound layers containing at least one charge transporting polyester having a repeating unit that contains at least one structure selected from structures represented by the following formula (I-1) as a partial structure.