Organic EL Compound Structure for Longer Element Life
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Solution Overview
Problem
Existing organic compounds used in organic light-emitting elements, such as those described in Patent Literature 1 and 2, have room for improvement in terms of element life characteristics.
Innovation Solution
An organic compound with a specific structure, represented by general formula [1], featuring a tricyclic or higher polycyclic fused ring at positions 4 and 3″ of 1,1′:3′,1″-terphenyl, which reduces the energy difference between the excited singlet and triplet states (ΔST), lowers symmetry, and has no substituents at other positions, enhancing amorphousness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compounds with fused polycyclic groups substituted at the end of a phenylene chain (compounds 1-A and 1-B) are used, then the organic light-emitting element can be realized with low drive voltage and various emission wavelengths, but the element life characteristics show room for improvement
Solution Approach 1:
The patent applies asymmetry by placing fused polycyclic groups at specific positions (4 and 3'' of 1,1′:3′,1″-terphenyl) rather than at the ends of the phenylene chain. This asymmetric substitution pattern improves element life characteristics while maintaining the desired optical and electrical properties, resolving the contradiction between reliability and structural design complexity
Solution Approach 2:
The patent implements local quality by introducing specific substituents (fused polycyclic groups) at particular positions of the terphenyl core structure. This localized modification enhances element life characteristics without requiring complete structural redesign, thus improving reliability while keeping the manufacturing approach feasible
2Reliability
If the organic compound has high symmetry structure, then the compound structure is simpler, but the amorphousness and stability are reduced leading to poorer element life characteristics
Solution Approach 1:
The patent deliberately introduces asymmetry by substituting fused polycyclic groups at positions 4 and 3'' of the 1,1′:3′,1″-terphenyl core, which breaks the symmetry of the molecular structure. This asymmetric design enhances amorphousness and stability of the organic compound layer, leading to improved element life characteristics
Solution Approach 2:
The patent changes the structural parameters of the organic compound by selecting specific fused polycyclic groups (such as dibenzofuran, dibenzothiophene, fluorene) and their substitution positions, which modifies the molecular symmetry and packing properties, thereby improving both amorphousness and element stability
3Reliability
If substituents are added at multiple positions of the phenylene chain, then the compound can achieve various emission wavelengths, but the element life characteristics deteriorate due to increased structural complexity and bond cleavage risk
Solution Approach 1:
The patent applies local quality by limiting substitutions to specific positions (4 and 3'') of the 1,1′:3′,1″-terphenyl core with fused polycyclic groups. This localized substitution approach achieves the desired emission wavelengths while minimizing structural complexity and reducing the risk of bond cleavage, thus improving element life characteristics
Solution Approach 2:
The patent creates composite molecular structures by combining the 1,1′:3′,1″-terphenyl core with fused polycyclic groups (such as dibenzofuran, dibenzothiophene, fluorene). This composite structure achieves versatile emission wavelengths while maintaining structural stability through the robust fused ring systems, resolving the contradiction between functionality and reliability
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 organic compound improves the life characteristics of the organic light-emitting element by enabling low-voltage driving, high light emission efficiency, and durability due to its low ΔST, low symmetry, and high sublimability, resulting in a stable amorphous film and reduced bond cleavage.
Implementation Method 1
An organic light-emitting element (hereinafter sometimes referred to as an 'organic electroluminescent element' or an 'organic EL element') is an electronic element that includes a pair of electrodes and an organic compound layer between the electrodes. Electrons and holes are injected from the pair of electrodes to generate an exciton of a light-emitting organic compound in the organic compound layer. When the exciton returns to its ground state, the organic light-emitting element emits light.
Data Source
AI summary
The present disclosure provides an organic compound represented by the following general formula [1].