Triazole Derivative Host Material for OLED Hole Injection
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Solution Overview
Problem
Current light-emitting elements using phosphorescent compounds face challenges with hole injection due to high singlet excitation energy materials like TAZ, leading to concentration quenching and reduced emission efficiency, necessitating a substance with high triplet excitation energy that facilitates hole injection and suppresses concentration quenching.
Innovation Solution
Incorporating a triazolo[4,3-f]phenanthridine derivative or triazolo[3,4-a]isoquinoline derivative as a host material in the light-emitting layer, which facilitates hole injection and has high triplet excitation energy, thereby improving emission efficiency and reducing concentration quenching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TAZ (3-(4-biphenylyl)-5-(4-tert-butylphenyl)-4-phenyl-1,2,4-triazole) is used as a host material for phosphorescent compounds, then triplet excitation energy is high which suppresses concentration quenching, but hole injection is hampered due to high singlet excitation energy
Solution Approach 1:
The patent modifies the molecular structure of TAZ by introducing electron-donating groups (such as carbazolyl, dibenzothiophenyl, or dibenzofuranyl groups) at specific positions (positions 1 or 5 of the triazole ring). This structural modification changes the energy parameters of the host material, specifically lowering the singlet excitation energy while maintaining high triplet excitation energy, thereby enabling both effective hole injection and suppression of concentration quenching
Solution Approach 2:
The patent creates composite host materials by combining the modified triazole derivative (which provides electron transport and appropriate energy levels) with phosphorescent guest materials. This composite approach allows the host material to facilitate hole injection through its modified structure while simultaneously suppressing concentration quenching through maintained high triplet energy, achieving both previously conflicting requirements
2Reliability
If phosphorescent compounds are dispersed in a host material matrix, then concentration quenching is suppressed, but emission efficiency is reduced due to poor hole injection
Solution Approach 1:
By modifying the host material structure to include electron-donating groups, the patent changes the energy level parameters to enable efficient hole injection into the light-emitting layer. This resolves the contradiction by allowing the dispersed phosphorescent compound system to maintain both suppression of concentration quenching and high emission efficiency through improved charge transport
Solution Approach 2:
The modified triazole derivative acts as an intermediary host material that mediates between the phosphorescent guest material and the charge carriers. Its modified structure with electron-donating groups facilitates hole injection and transport to the dispersed phosphorescent compounds, enabling efficient energy transfer while maintaining the benefits of dispersion (suppression of concentration quenching)
3Productivity
If a phosphorescent compound is used to achieve high internal quantum efficiency, then emission efficiency increases to 75-100%, but hole injection becomes difficult due to the nature of phosphorescent materials
Solution Approach 1:
The modified triazole derivative serves as an intermediary host material that bridges the gap between the charge carriers and the phosphorescent compound. Its electron-donating groups facilitate hole injection and transport, while its high triplet energy prevents energy loss, enabling the phosphorescent compound to achieve high internal quantum efficiency without suffering from poor hole injection
Solution Approach 2:
The patent changes the energy level parameters of the host material by introducing electron-donating groups, which lowers the singlet excitation energy to facilitate hole injection while maintaining high triplet excitation energy. This parameter modification enables the system to achieve both easy hole injection and high phosphorescent 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 use of these derivatives enhances emission efficiency, allows for low-voltage operation, and extends the lifetime of light-emitting elements while reducing power consumption, resulting in high-performance light-emitting devices.
Implementation Method 1
a light-emitting layer between a pair of electrodes and in which the light-emitting layer includes a phosphorescent material and a triazolo[4,3-f]phenanthridine derivative or a triazolo[3,4-a]isoquinoline derivative
Implementation Method 2
with a compound that can convert energy of a triplet excited state into luminescence (hereinafter, called a phosphorescent compound), luminescence from the triplet excited state (phosphorescence) is observed
Implementation Method 3
research and development have been extensively conducted on light-emitting elements utilizing electroluminescence (EL)
Data Source
AI summary
A triazole derivative represented by General Formula (G0) is provided. In the General formula (G0), A represents a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted dibenzothiophenyl group, or a substituted or unsubstituted dibenzofuranyl group, E represents substituted or unsubstituted triazolo [4,3 f]phenanthridine or substituted or unsubstituted triazolo [3,4-α]isoquinoline, and Ar represents a substituted or unsubstituted arylene group having 6 to 13 carbon atoms.E-Ar-A (G0)