OLED Host Compound Structure to Suppress Conjugation Spread
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Solution Overview
Problem
Existing organic compounds for organic light-emitting elements, such as Compound 1-a, exhibit low lowest excited triplet (T1) energy values, which affects the efficiency and longevity of the elements.
Innovation Solution
The development of an organic compound represented by formula (1) with specific structural components, including an indolocarbazole skeleton and a fluorene or spirofluorene skeleton, designed to suppress conjugation spread and enhance T1 energy by limiting aryl and heterocyclic groups, thereby improving energy transfer and reducing molecular aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Compound 1-a (2-substituted fluorene with indolocarbazole and dibenzofuran substituents) is used, then the compound can be synthesized and processed, but the lowest excited triplet (T1) energy value is low
Solution Approach 1:
The patent changes the molecular structure parameters of the organic compound by introducing a spirofluorene skeleton instead of a fluorene skeleton, and by selecting specific substituents (indolocarbazole at position 2 and dibenzofuran at position 7 of the spirofluorene core). This structural parameter change increases the T1 energy value from 2.7 eV (Compound 1-a) to 2.9-3.1 eV (Compounds of Formula 1), thereby improving element life characteristics while maintaining processability
Solution Approach 2:
The patent creates a composite molecular structure combining the spirofluorene skeleton with indolocarbazole and dibenzofuran substituents. This composite structure leverages the high T1 energy of the spirofluorene core (2.9-3.1 eV) while the substituents provide appropriate energy levels and molecular interactions, achieving both high T1 energy and good element life characteristics
2Use of energy by moving object
If compounds with higher T1 energy are developed, then element life characteristics improve, but molecular aggregation and quencher molecule generation increase
Solution Approach 1:
The patent applies local quality by introducing bulky substituents (indolocarbazole and dibenzofuran) at specific positions (2 and 7) of the spirofluorene core. These substituents create steric hindrance locally at the molecular level, preventing close packing and aggregation of high-T1 energy molecules, thereby reducing quencher molecule generation while maintaining the high T1 energy (2.9-3.1 eV) needed for long element life
3Use of energy by moving object
If the conjugation spread is enhanced, then light emission efficiency improves, but T1 energy value decreases
Solution Approach 1:
The patent changes the conjugation parameter by using a spirofluorene skeleton with orthogonal pi-systems instead of a planar fluorene skeleton. This structural change limits conjugation spread while maintaining adequate light emission efficiency through the spirofluorene core's inherent photophysical properties, achieving T1 energy of 2.9-3.1 eV without significant loss in light emission efficiency
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 achieves higher T1 energy, enhancing light emission efficiency and element life by accelerating energy transfer to phosphorescent dopants and reducing quencher molecule generation, while maintaining compatibility with the dopants.
Implementation Method 1
enhancing light emission efficiency and element life by accelerating energy transfer to phosphorescent dopants
Implementation Method 2
An exciton of a light-emitting organic compound in the organic compound layer is generated by injection of an electron and a hole from the pair of electrodes, and the organic light-emitting element emits light when the exciton returns to the ground state
Data Source
AI summary
An organic compound represented by formula (1):(A)n1-L-(B)n2 (1)in the general formula (1), (A) has a structure represented by a general formula (2), and (B) has a structure represented by a general formula (3) or a general formula (4):in the general formulae (2) to (4), R101 to R316 are each a hydrogen atom or any substituent; L is a linking group; one of R101 to R111 in the general formula (2), one of R201 to R208 in the general formula (3), and one of R301 to R308 in the general formula (4) are the binding positions to L.