Heterocyclic Compound Crystallization Suppression
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Solution Overview
Problem
Light-emitting elements with compounds that easily crystallize, such as those containing a dibenzo[f,h]quinoxaline ring, suffer from short lifetimes and decreased triplet excitation energy, leading to lower emission efficiency due to their planar structures and potential for crystallization, which affects the characteristics of the light-emitting element.
Innovation Solution
A novel heterocyclic compound is developed, where a substituted or unsubstituted dibenzo[f,h]quinoxalinyl group is bonded to a benzobisbenzofuranyl group via an arylene group, creating a bulky structure that suppresses crystallization and maintains high triplet excitation energy, thereby improving heat resistance and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar structure compound (dibenzo[f,h]quinoxaline ring) is used, then the compound is easy to crystallize, but the light-emitting element has short lifetime and low emission efficiency
Solution Approach 1:
The patent transitions from a two-dimensional planar structure to a three-dimensional bulky structure by introducing spirobifluorene groups and other bulky substituents. This dimensional change prevents close packing of molecules, thereby suppressing crystallization while maintaining the core dibenzo[f,h]quinoxaline structure for desired electronic properties.
Solution Approach 2:
The patent introduces asymmetric bulky groups (spirobifluorene, adamantane, etc.) attached to the symmetric dibenzo[f,h]quinoxaline core. This asymmetry disrupts the regularity needed for crystallization, preventing the formation of ordered structures that would lead to short device lifetime.
2Reliability
If another skeleton is directly bonded to the dibenzo[f,h]quinoxaline ring to create a bulky structure, then crystallization is suppressed, but the conjugated system extends causing decrease in triplet excitation energy and lower emission efficiency
Solution Approach 1:
The patent segments the molecular structure by introducing flexible linker groups (alkylene chains, alkoxy groups) between the dibenzo[f,h]quinoxaline core and the bulky spirobifluorene groups. This segmentation prevents direct conjugation while maintaining spatial separation, thus preserving high triplet excitation energy while achieving crystallization suppression.
Solution Approach 2:
The patent uses intermediary groups (alkylene chains, alkoxy linkers) that connect the dibenzo[f,h]quinoxaline core to the bulky spirobifluorene groups. These intermediaries act as insulators that prevent extension of the conjugated system, thereby maintaining high triplet excitation energy while still providing the steric bulk needed to prevent crystallization.
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 novel heterocyclic compound enhances the heat resistance and emission efficiency of light-emitting elements, leading to longer lifetimes and reduced power consumption while maintaining high triplet excitation energy, thus addressing the limitations of easily crystallizable compounds.
Implementation Method 1
Compounds having a dibenzo[f,h]quinoxaline ring which are reported in Patent Document 1 have planar structures and are thus easily crystallized, which is a problem. A light-emitting element using a compound that is easy to crystallize has a short lifetime.
Implementation Method 2
when a voltage is applied between a pair of electrodes with an EL layer including a luminous body provided therebetween, electrons injected from the cathode and holes injected from the anode recombine in the light emission center of the EL layer to form molecular excitons, and energy is released and light is emitted when the molecular excitons relax to the ground state
Implementation Method 3
A singlet excited state and a triplet excited state are known as excited states, and it is thought that light emission can be achieved through either of the excited states. When the triplet excitation energy decreases, emission efficiency is lowered
Data Source
AI summary
A novel heterocyclic compound is provided. In particular, a novel heterocyclic compound which can improve the element characteristics of the light-emitting element is provided. The heterocyclic compound is represented by a general formula (G1)DBqAr1nAr2-A (G1)in which a substituted or unsubstituted dibenzo[f,h]quinoxalinyl group and a substituted or unsubstituted benzobisbenzofuranyl group are bonded to each other via a substituted or unsubstituted arylene group. In the general formula (G1), DBq represents a substituted or unsubstituted dibenzo[f,h]quinoxalinyl group, Ar1 represents a substituted or unsubstituted arylene group having 6 to 13 carbon atoms, n represents 0 or 1, Ar2 represents a substituted or unsubstituted arylene group having 6 to 13 carbon atoms, and A represents a substituted or unsubstituted benzobisbenzofuranyl group. When the arylene group represented by Ar1 and Ar2 has substituents, the substituents may be bonded to each other to form a ring.