Polymer Compound for Organic EL Driving Voltage and Durability
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Solution Overview
Problem
Existing organic electroluminescence (EL) elements face challenges with high driving voltage and low durability due to the limitations of low molecular compounds used in their production, particularly in forming uniform organic layers and maintaining phosphorescent properties.
Innovation Solution
A polymer compound with a specific aromatic heterocyclic structure is developed, serving as both an electron-transporting and hole-transporting site, which lowers the driving voltage and enhances durability by incorporating a monomer with a polymerizable functional group, allowing for efficient carrier transport and luminous properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low molecular compounds are used to form organic layers in organic EL elements, then the production process can be simplified, but the film thickness becomes uneven and vacuum equipment is required
Solution Approach 1:
The patent changes the molecular weight parameter of the organic material from low molecular compound to polymer compound. This parameter change enables the material to be processed into uniform films without vacuum equipment, as polymers can be applied by solution casting or coating methods that inherently produce more uniform thickness compared to vapor deposition of low molecular compounds.
Solution Approach 2:
The patent uses composite material structure by combining polymer backbone with specific functional groups (electron-transporting and hole-transporting moieties). This composite approach allows the material to exhibit both ease of processing like conventional organics and improved film formation characteristics, eliminating the need for vacuum equipment while maintaining uniform thickness.
2Reliability
If compounds with conjugatable nitrogen atoms are used to enhance charge transport, then carrier mobility improves, but excimer formation and polarization phenomenon increase causing reduced durability
Solution Approach 1:
The patent applies local quality by placing electron-transporting and hole-transporting functional groups at specific local positions on the polymer backbone, rather than having extensive conjugated systems throughout. This localized functional group approach maintains charge transport capability while preventing the formation of excimers and polarization phenomena that occur in highly conjugated systems.
Solution Approach 2:
The patent segments the charge transport function into separate electron-transporting groups and hole-transporting groups attached to the polymer backbone. This segmentation prevents the formation of continuous conjugated pathways that lead to excimer formation, while still providing effective bipolar charge transport through the distributed functional groups.
3Manufacturing precision
If polymer compounds are used to improve film uniformity, then manufacturing complexity increases, but the patent aims to simplify the process
Solution Approach 1:
The patent enables self-service processing by designing the polymer compound to form uniform films through simple solution-based methods without requiring complex vacuum equipment. The polymer's inherent properties allow it to self-organize into uniform films during conventional coating processes, eliminating the need for sophisticated manufacturing infrastructure.
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 polymer compound enables the production of organic EL elements with reduced driving voltage and improved durability, achieving high luminous efficiency and stability.
Implementation Method 1
the polymer compound having a specific aromatic heterocyclic structure as an electron-transporting site and a hole-transporting site
Implementation Method 2
the polymer compound having a specific aromatic heterocyclic structure as an electron-transporting site and a hole-transporting site
Implementation Method 3
organic electroluminescence elements (hereinafter optionally referred to 'organic EL element')
Data Source
Figure 1
AI summary
The present invention provides a polymer material capable of preparing organic EL elements having low driving voltage and high durability. The polymer compound of the present invention includes a constituting unit derived from a monomer represented by the formula (1); (in the formula (1), each of A1's is independently a condensed polycyclic aromatic group optionally having a heteroatom as a ring-constituting atom; the condensed polycyclic aromatic group links to A2 at the meta position to the bonding position of the ring represented by the following formula; each of A2's is independently a six-membered ring aromatic group optionally having a heteroatom as a ring-constituting atom; at least one of A1 and A2 has a substituent having a polymerizable functional group; at least one of X's is a nitrogen atom, and n's are independently 1 or 2).