Heterocyclic Compound for OLED Host Material
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Solution Overview
Problem
Light-emitting elements with planar structures, such as those containing dibenzo[f,h]quinoxaline rings, have short lifetimes due to easy crystallization and poor hole-acceptance properties, leading to reduced efficiency and reliability.
Innovation Solution
A heterocyclic compound with a dibenzo[f,h]quinoxaline ring bonded through an arylene group to a hole-transport skeleton, which enhances hole-acceptance and prevents crystallization, maintaining triplet excitation energy and extending the conjugated system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a planar structure containing dibenzo[f,h]quinoxaline rings is used, then the conjugated system is extended and triplet excitation energy is maintained, but the compound easily crystallizes and has poor hole-acceptance properties, leading to short lifetime
Solution Approach 1:
The patent transitions from a two-dimensional planar structure to a three-dimensional non-planar structure by introducing sp³ hybridized carbon atoms that create twisted conformations. This dimensional change prevents crystallization while preserving the conjugated system and triplet excitation energy, thereby extending the lifetime of the light-emitting element.
Solution Approach 2:
The patent creates a composite molecular structure combining dibenzo[f,h]quinoxaline rings with various heterocyclic groups (carbazole, dibenzothiophene, dibenzofuran) connected through arylene groups. This composite approach maintains the beneficial optical properties while introducing structural complexity that prevents crystallization and improves hole-acceptance properties.
2Productivity
If a planar structure is used, then the conjugated system is extended, but hole-acceptance properties deteriorate, leading to reduced current efficiency
Solution Approach 1:
The patent introduces three-dimensional non-planar structures through sp³ hybridized carbons and twisted conformations, which improve hole-acceptance properties by creating more favorable electron density distributions while preserving the extended conjugated system for maintaining optical properties.
Solution Approach 2:
The patent applies local structural modifications at specific positions within the molecule (introducing heterocyclic groups at strategic locations connected via arylene groups) to enhance hole-acceptance properties without compromising the overall conjugated system and triplet excitation energy.
3Reliability
If the compound structure is simplified, then ease of manufacture is improved, but reliability deteriorates due to easy crystallization
Solution Approach 1:
The patent employs composite molecular structures built from well-established heterocyclic building blocks (carbazole, dibenzothiophene, dibenzofuran) connected through standard arylene linkers. These components can be synthesized using conventional organic synthesis methods, balancing structural complexity for preventing crystallization with manufacturability through modular assembly.
Solution Approach 2:
The patent systematically varies structural parameters (different heterocyclic groups, substitution patterns, arylene linkers) to optimize the balance between preventing crystallization and maintaining ease of synthesis, allowing selection of compounds based on specific application requirements while using standard synthetic protocols.
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 compound achieves low driving voltage, high current efficiency, and long lifetime for light-emitting elements, reducing power consumption and improving device reliability.
Implementation Method 1
a heterocyclic compound with a dibenzo[f,h]quinoxaline ring bonded through an arylene group to a hole-transport skeleton, which enhances hole-acceptance
Implementation Method 2
maintaining triplet excitation energy and extending the conjugated system
Implementation Method 3
light-emitting elements utilizing electroluminescence (EL). In the basic structure of such a light-emitting element, a layer containing a light-emitting substance is interposed between a pair of electrodes. By voltage application to this element, light emission from the light-emitting substance can be obtained.
Data Source
AI summary
An object is to provide a novel heterocyclic compound which can be used for a light-emitting element, as a host material of a light-emitting layer in which a light-emitting substance is dispersed. Other objects are to provide a light-emitting element having low driving voltage, a light-emitting element having high current efficiency, and a light-emitting element having a long lifetime. Provided are a light-emitting element including a compound in which a dibenzo[f,h]quinoxaline ring and a hole-transport skeleton are bonded through an arylene group, and a light-emitting device, an electronic device, and a lighting device each using this light-emitting element. The heterocyclic compound represented by General Formula (G1) below is provided.