Organic Charge-Transporting Material for OLED Heat Resistance
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges with charge transportability, heat resistance, and amorphous nature due to limitations in polymer materials like polyaniline and 1,3-dihydroimidazol-2-one derivatives, which affect light-emission efficiency and device longevity.
Innovation Solution
A novel organic compound with a 1,3-dihydroimidazol-2-one structure and urea bond, offering improved heat resistance, amorphous nature, and charge transportability, is developed, allowing for the formation of high-brightness, long-life organic electroluminescent devices using a wet film-forming method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer materials like polyaniline are used to increase charge transportability, then charge transportability is improved, but heat resistance deteriorates and degradation occurs during continuous driving
Solution Approach 1:
The patent changes the chemical structure parameters by introducing a 1,3-dihydroimidazol-2-one core with urea bonds and aromatic substituents, transforming the material from a polymer to a small molecule compound. This structural parameter change simultaneously improves charge transportability through the urea bond's electron delocalization and heat resistance through the aromatic ring's thermal stability, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite molecular structure combining the 1,3-dihydroimidazol-2-one core, urea bonding units, and aromatic hydrocarbon groups. This composite structure integrates the charge-transporting capability of the urea bond with the thermal stability of aromatic rings, achieving both improved charge transportability and heat resistance without the degradation issues of polymer materials.
2Reliability
If 1,3-dihydroimidazol-2-one derivatives are used to improve charge transportability, then charge transportability is improved, but heat resistance and amorphous nature deteriorate
Solution Approach 1:
The patent modifies the molecular parameters by incorporating rigid aromatic hydrocarbon groups (such as phenyl, naphthyl, or anthryl groups) as substituents on the 1,3-dihydroimidazol-2-one core. This parameter change increases the glass transition temperature and enhances the amorphous nature of the material, thereby improving heat resistance and compositional stability while preserving the charge transportability provided by the urea bond structure.
3Use of energy by moving object
If phosphorescent emission is utilized to increase light-emission efficiency, then light-emission efficiency is improved, but sufficient luminance and lifetime are not obtained
Solution Approach 1:
The patent changes the energy level parameters of the charge-transporting material by optimizing the HOMO and LUMO levels through selective substitution on the 1,3-dihydroimidazol-2-one core. This parameter optimization improves electron injection efficiency and charge carrier mobility, enabling sufficient luminance and extended device lifetime when used in conjunction with phosphorescent emitters, thereby resolving the limitation of insufficient operational duration.
Data Source
AI summary
An organic compound having excellent heat resistance, an excellent amorphous nature, an excellent ability to transport charges, highly excited singlet and triplet states, and excellent solubility in an organic solvent is an organic compound represented by Formula (I):wherein Ar1 represents an optionally-substituted aromatic hydrocarbon group, an optionally-substituted aromatic heterocyclic group, or an optionally-substituted alkyl group; Ar2 represents an optionally-substituted aromatic hydrocarbon group or an optionally-substituted aromatic heterocyclic group; R1 and R2 each represent a hydrogen atom or a substituent, and R1 and R2 may be bonded to each other to form a ring; and Q is represented by Formula (I-1) or (I-2):wherein Ar3 to Ar5 each represent an optionally-substituted aromatic hydrocarbon group or an optionally-substituted aromatic heterocyclic group, and Ar3 and Ar4 may be bonded to each other to form a ring.