Imine Derivative Hole-Injecting Layer for OLED Voltage Reduction
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Solution Overview
Problem
Organic electroluminescent devices using aromatic diamine derivatives as hole-transporting materials require high voltages, leading to shorter device lifetimes and higher power consumption, and existing electron-accepting compounds used to address this issue are unstable and prone to contamination during production.
Innovation Solution
Development of imine derivatives with specific structures, such as those represented by formulas (Ia) and (IIa), which act as electron-accepting materials, providing improved heat resistance and stability during device production, allowing for lower driving voltage and longer device lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If aromatic diamine derivatives are used as hole-transporting materials, then device structure can be simplified, but driving voltage increases leading to shorter lifetime and higher power consumption
Solution Approach 1:
The patent introduces a hole-injecting layer as an intermediary component between the anode and hole-transporting layer. This layer uses electron-accepting compounds to facilitate hole injection, thereby reducing the driving voltage requirement and extending device lifetime without complicating the overall device structure.
2Power
If electron-accepting compounds are doped in hole-injecting layer, then driving voltage decreases, but device stability and heat resistance worsen
Solution Approach 1:
The patent modifies the chemical parameters of electron-accepting compounds by introducing specific molecular structures (formula I with Y1-Y4 as C or N atoms, and formula II with specific R groups) that enhance thermal stability and heat resistance while maintaining electron-accepting capability, thus reducing driving voltage without compromising device stability.
3Power
If TCNQF4 is used as electron-accepting compound, then driving voltage is reduced, but device contamination increases due to sublimation and scattering
Solution Approach 1:
The patent changes the molecular weight and chemical composition parameters of electron-accepting compounds by designing structures with higher molecular weights and specific atomic compositions (C, H, N, O, F) that reduce sublimation tendency. This prevents scattering and contamination during vacuum deposition while maintaining the voltage-reducing effect.
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 imine derivatives enable organic electroluminescent devices to be driven at lower voltages while maintaining stability and preventing contamination, resulting in longer device lifetimes and improved performance.
Implementation Method 1
a hole-injecting layer made of an imine derivative represented by formula (I) or (II) of the invention... the imine derivatives enable organic electroluminescent devices to be driven at lower voltages
Implementation Method 2
An organic electroluminescence device (hereinafter the term 'electroluminescent' is often abbreviated as 'EL') is a self-emission device utilizing the principle that a fluorescent compound emits light by the recombination energy of holes injected from an anode and electrons injected from a cathode when an electric field is impressed
Implementation Method 3
They may scatter in an apparatus during the production of an organic EL device by vacuum deposition, resulting in contamination of the apparatus and device
Data Source
AI summary
A material for an organic electroluminescent device including an imine derivative represented by the following formula (Ia) or (Ib),wherein Y1 to Y4 are independently a carbon atom or a nitrogen atom; R1 to R4 are independently hydrogen, an alkyl group, an aryl group, a heterocycle, a halogen atom, a fluoroalkyl group or a cyano group; and R1 and R2, or R3 and R4 may be bonded together to form a ring.