Acridine Core Hole Transporting Material for OLED Energy Level Matching

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Solution Overview

Problem

Existing OLED devices face issues with hole transporting materials having mismatched highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, leading to low hole mobility and luminous efficiency.

Innovation Solution

A hole transporting material with an acridine structure as the core, combined with various functional groups such as carbazole, diphenylamine, phenoxazine, and their derivatives, is synthesized using a specific manufacturing method involving reactants, palladium acetate, and tri-tert-butylphosphine tetrafluoroborate, resulting in a material with suitable energy levels and high mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional hole transporting materials are used in OLED devices, then the device structure can be maintained, but the HOMO and LUMO energy levels are mismatched resulting in low hole mobility and luminous efficiency

Engineering Contradiction:

Improveluminous efficiencyVSAvoidenergy level matching

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent modifies the molecular structure of hole transporting materials by introducing specific functional groups (carbazole, diphenylamine, phenoxazine, acridine) to change the HOMO and LUMO energy levels. This parameter optimization ensures better energy level matching with adjacent layers, thereby improving hole mobility and luminous efficiency without compromising device structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite molecular structures combining electron-donating groups (carbazole, diphenylamine, phenoxazine) with electron-accepting groups (acridine). This composite approach creates materials with optimized energy levels and enhanced charge transport properties, resolving the energy level mismatch problem while maintaining structural integrity

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If the hole transport layer thickness is increased to maintain device structure, then structural stability is improved, but energy level mismatch and low hole mobility persist affecting luminous efficiency

Engineering Contradiction:

Improvelayer stabilityVSAvoidhole mobility

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

By changing the molecular parameters of the hole transporting material (introducing specific functional groups with appropriate electron-donating or electron-accepting properties), the patent achieves better energy level alignment. This allows for optimized charge transport within the existing layer thickness, improving hole mobility without requiring structural changes

Inventive Principle:

Principle #35Parameter changes

3Productivity

If heavy metal complex phosphorescent materials are used to achieve 100% internal quantum efficiency, then luminous efficiency is improved, but the use of precious metals like iridium and platinum increases cost and blue light material development remains limited

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoidprecious metal content

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent replaces expensive heavy metal complexes with organic-based hole transporting materials containing common elements (C, H, N, O). These organic materials achieve improved charge transport and energy level matching without relying on precious metals, reducing cost while maintaining high device performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent optimizes the chemical composition and molecular structure of organic hole transporting materials to achieve energy levels and charge mobility comparable to or exceeding heavy metal complexes, providing a cost-effective alternative that eliminates dependence on iridium and platinum

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11450815B2Hole transporting material, method of manufacturing same and organic electroluminescent device

Publication Date: 2022.09.20 WUHAN CHINA STAR OPTOELECTRONICS SEMICONDUCTOR DISPLAY TECHNOLOGY CO LTD

AI summary

A hole transporting material is disclosed, and has a structural formula as shown in a formula (A):wherein R group of the hole transporting material is one of a carbazole group and a derivative group thereof, a diphenylamine group and a derivative group thereof, a phenoxazine group and a derivative group thereof, and an acridine group and a derivative group thereof. The hole transporting material is synthetized to have a suitable energy level and a high mobility by using an acridine structure as a core. An organic electroluminescent device based on the hole transporting material has high luminous efficiency.