Indeno[1,2-b]phenanthrene Compound for OLED Carrier Balance
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Solution Overview
Problem
The existing indeno[1,2-b]phenanthrene compounds used in organic light emitting elements have high planarity and low glass transition temperatures, leading to intensive intermolecular stacking and poor performance due to high hole transport ability and low carrier balance in light emitting layers.
Innovation Solution
A modified indeno[1,2-b]phenanthrene compound with a suppressed hole transport ability is developed, featuring a HOMO sparse moiety that reduces orbital overlap and enhances carrier balance by adjusting the molecular structure with specific substitutions, such as aromatic hydrocarbon groups at the 2-position of the indeno[1,2-b]phenanthrene skeleton.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-substituted indeno[1,2-b]phenanthrene is used as a fluorescent light emitting dopant, then the molecular size is small and glass transition temperature is low, but the intermolecular stack becomes intensive and hole transport ability becomes too high leading to poor carrier balance
Solution Approach 1:
The patent applies local quality by introducing specific substituents (aromatic hydrocarbon groups) at particular positions (2-position) of the indeno[1,2-b]phenanthrene core structure. This localized modification creates a HOMO sparse moiety at the substitution site, which locally suppresses hole transport while maintaining the overall molecular framework. The substituent at the 2-position specifically creates orbital sparsity that balances carrier distribution without requiring complete molecular redesign.
Solution Approach 2:
The patent changes molecular parameters by substituting hydrogen atoms with aromatic hydrocarbon groups (such as phenyl, naphthyl, anthryl groups). This parameter change increases molecular size and modifies electronic structure, creating a HOMO sparse region that reduces hole transport ability. The substitution transforms the electronic distribution pattern, creating localized areas of low HOMO density that prevent excessive hole accumulation and improve carrier balance.
2Device complexity
If indeno[1,2-b]phenanthrene compound with high planarity is used, then the molecular structure is simple, but the intermolecular stack is intensive leading to high hole transport ability and poor carrier balance
Solution Approach 1:
The patent maintains the overall planar structure of the indeno[1,2-b]phenanthrene core for simplicity but introduces local structural variations through substitution. The aromatic hydrocarbon group at the 2-position creates a local HOMO sparse moiety that disrupts the uniform electron distribution. This local modification allows the molecule to maintain structural simplicity while achieving the desired carrier balance through localized electronic property control.
Solution Approach 2:
The patent introduces asymmetry by substituting at the 2-position of the otherwise symmetric indeno[1,2-b]phenanthrene core. This asymmetric substitution creates an uneven electronic distribution, generating a HOMO sparse region on one side of the molecule. The asymmetric structure prevents uniform intermolecular stacking and reduces excessive hole transport while maintaining overall molecular simplicity.
3Quantity of substance
If non-substituted indeno[1,2-b]phenanthrene is used, then the molecular size is small, but the glass transition temperature is low leading to poor element performance
Solution Approach 1:
The patent creates a composite molecular structure by combining the indeno[1,2-b]phenanthrene core with aromatic hydrocarbon group substituents. This composite structure increases molecular size and complexity, which directly raises the glass transition temperature. The combination of core and substituent creates a larger, more rigid molecular structure that resists thermal motion, thereby improving thermal stability and element performance.
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 modified indeno[1,2-b]phenanthrene compound improves carrier balance and light emitting efficiency, resulting in an organic light emitting element with enhanced performance and longer lifespan by effectively managing hole mobility and carrier recombination.
Implementation Method 1
featuring a HOMO sparse moiety that reduces orbital overlap and enhances carrier balance
Implementation Method 2
holes and electrons, which are injected from the respective electrodes, are recombined with each other in the organic compound layer to generate excitons, and when the excitons are returned to the ground state, light is emitted
Implementation Method 3
a phosphorescent light emitting element is a light emitting element which includes a phosphorescent light emitting material in an organic compound layer and which can emit light derived from triplet excitons
Data Source
AI summary
The present invention provides an indeno[1,2-b]phenanthrene compound having suppressed hole transport ability. The indeno[1,2-b]phenanthrene compound represented by the general formula [1] described in claim 1 is provided. In the formula [1], R1 and R2 each represent a hydrogen atom or an alkyl group. X1 and X2 each represent a substituent selected from the group consisting of a hydrogen atom, an alkyl group, a methoxy group, and a cyano group. A1 represents a monovalent or a divalent aromatic hydrocarbon group. A2 represents a monovalent or a divalent aromatic hydrocarbon group or a monovalent or a divalent heteroaromatic group. n represents an integer of 0 to 4. When n is 2 or more, a plurality of A2 may be identical to or different from each other.