B-N Fused Ring OLED Materials for High Efficiency
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Solution Overview
Problem
Current organic light-emitting diode (OLED) materials face challenges with high driving voltage, low luminous efficiency, and poor color purity due to the limitations of phosphorescent, fluorescent, and thermally activated delayed fluorescence (TADF) materials, particularly related to heavy metal content, material stability, and spectral width.
Innovation Solution
The development of organic luminescent materials containing B—N fused rings, which utilize a thermally activated delayed fluorescence (TADF) mechanism and incorporate indolo[3,2,1-JK]carbazole derivatives to achieve a multiple resonance effect, resulting in materials with enhanced luminous efficiency and improved color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials are used to achieve 100% internal quantum efficiency, then luminous efficiency is improved, but material stability deteriorates and heavy metal content increases
Solution Approach 1:
The patent replaces expensive phosphorescent materials containing heavy metals with organic electroluminescent materials that have shorter lifetimes but achieve comparable luminous efficiency through TADF mechanism, eliminating the need for rare metals like iridium and platinum
Solution Approach 2:
The patent modifies the molecular structure by introducing B-N fused ring structures with specific electronic properties, adjusting HOMO-LUMO energy levels and optimizing singlet-triplet energy splitting to achieve efficient TADF without heavy metals
2Use of energy by moving object
If TADF materials are used to achieve 100% internal quantum efficiency, then luminous efficiency is improved, but color purity deteriorates due to large spectrum half-wave width
Solution Approach 1:
The patent introduces rigid B-N fused ring structures at specific positions in the molecule to locally enhance resonance effects and restrict molecular vibrations, thereby narrowing the emission spectrum without affecting the overall TADF mechanism
Solution Approach 2:
The patent combines multiple functional units including B-N fused rings, indolo[3,2,1-JK]carbazole derivatives, and electron-donating/withdrawing groups to create composite molecular structures that simultaneously achieve efficient TADF and narrow emission spectra
3Reliability
If fluorescent materials are used for blue light emission, then material stability is maintained, but luminous efficiency deteriorates with theoretical efficiency limited to 40%
Solution Approach 1:
The patent introduces triplet excitons as an intermediary energy state that can be converted to singlet excitons through reverse intersystem crossing in TADF materials, enabling utilization of both singlet and triplet carriers for light emission and achieving 100% internal quantum efficiency
4Manufacturing precision
If phosphorescent materials are used for green and red light emission, then color purity is improved, but cost increases due to heavy metal content
Solution Approach 1:
The patent replaces expensive phosphorescent materials containing iridium and platinum with organic electroluminescent materials based on TADF mechanism, achieving comparable color purity and luminous efficiency without relying on rare and expensive metals
Solution Approach 2:
The patent extracts and eliminates heavy metal components from the luminescent material system while retaining the essential functionality of phosphorescent materials through the development of metal-free TADF emitters with optimized molecular structures
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
These materials achieve internal quantum efficiency of 100% with a small half-wave width, excellent thermal stability, and superior color purity, addressing the limitations of existing OLED materials.
Implementation Method 1
Based on the principle of TADF, B—N fused ring structures of the materials can achieve a multiple resonance effect
Implementation Method 2
B—N fused ring structures of the materials can achieve a multiple resonance effect
Implementation Method 3
with introduction of indolo[3,2,1-JK]carbazole and derivatives thereof, the multiple resonance effect is further enhanced
Implementation Method 4
Resulting molecules have large rigid planes, intramolecular vibration can be effectively inhibited
Data Source
AI summary
The present invention relates to a series of organic electroluminescent materials containing B—N fused rings, which has a structure represented by Formula (I). Based on the principle of thermally activated delayed fluorescence (TADF), the materials have internal quantum efficiency of 100%. In addition, by utilizing a multiple resonance effect between B—N, the materials have small half-wave width and good color purity. With introduction of indolo[3,2,1-JK]carbazole, the multiple resonance effect is further enhanced, and the luminous efficiency and the color purity are significantly improved. Moreover, such compounds have good thermal stability and meet requirements of OLED panels for luminescent materials. The present invention further provides an organic electroluminescent device, and at least one of organic layers in the device contains the compound represented by Structural Formula (I).