Boron-Based TADF Organic Compounds for Stable OLED Emission
Solution Overview
Problem
Existing TADF materials for OLEDs lack diversity, performance, and are costly, limiting the efficiency and stability of OLED devices.
Innovation Solution
An organic compound with a specific molecular structure, represented by Formula I, featuring suitable HOMO and LUMO energy levels, high singlet and triplet energy levels, and a small energy level difference, is designed to enhance exciton recombination and stability, utilizing boron-containing aromatic compounds for improved TADF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent material is used in OLED, then internal quantum yield can reach 100%, but production cost is high and stability is poor
Solution Approach 1:
The patent replaces expensive phosphorescent materials containing heavy metals (Ir, Pt, Os, Re, Ru) with organic TADF materials that are cheaper and can be produced at scale. The TADF materials achieve comparable efficiency without the stability issues of phosphorescent materials, effectively substituting a costly, unstable solution with a economical, stable alternative.
Solution Approach 2:
The patent modifies molecular parameters by designing specific organic compound structures with tailored HOMO-LUMO energy levels and small S1-T1 energy gaps. This enables efficient reverse intersystem crossing and high internal quantum yield without requiring heavy metals, thus improving both cost-effectiveness and device stability while maintaining high efficiency.
2Ease of manufacture
If fluorescent material is used in OLED, then production cost is low, but external quantum efficiency is not more than 5%
Solution Approach 1:
The patent changes the energy level parameters of organic compounds to create a small energy gap between S1 and T1 states (ΔEST ≤ 0.30 eV). This enables efficient reverse intersystem crossing from triplet to singlet state, allowing TADF materials to utilize both singlet and triplet excitons for light emission, thereby achieving external quantum efficiency >20% while maintaining low production costs associated with organic materials.
Solution Approach 2:
The patent employs composite molecular structures combining electron-donating groups (containing B, Si, or C atoms) with electron-accepting groups. This composite approach creates push-pull systems with appropriate energy level alignment, enabling high efficiency TADF emission while using cost-effective organic components rather than expensive phosphorescent complexes.
3Use of energy by moving object
If TADF material with small ΔEST is used, then internal quantum yield can reach 100%, but material diversity is limited
Solution Approach 1:
The patent divides the TADF molecule into distinct functional segments: electron-donating groups (with B, Si, or C atoms) and electron-accepting groups connected by linking units. This segmentation allows independent optimization of each component's properties while maintaining the overall small ΔEST requirement, enabling diverse material designs with varied energy levels, emission colors, and molecular properties.
Solution Approach 2:
The patent applies local quality by allowing different substituents (R1-R7) at specific positions on the molecular framework. These substituents can be independently selected to tune local electronic properties, steric effects, and energy levels, creating material diversity while maintaining the core TADF mechanism and high internal quantum yield performance.
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 organic compound achieves higher luminescence efficiency, reduces turn-on voltage, and extends the lifetime of OLED devices by enhancing thermal and film stability, while being cost-effective.
Implementation Method 1
when an energy level difference between the state S1 and the state T1 is relatively small, at a certain temperature, reverse intersystem crossing (RISC) occurs inside the molecule, excitons in the state T1 are converted to the state S1 by absorbing ambient heat
Implementation Method 2
A triplet excited state T1 of the phosphorescent material directly decays to the ground state S0 through radiation. Due to a heavy atom effect, intersystem crossing inside a molecule can be improved through spin coupling effect
Implementation Method 3
A singlet excited state S1 of the fluorescent material returns to a ground state S0 through radiation transition
Implementation Method 4
When a voltage is applied across the two electrodes of the OLED device, holes generated by the anode and electrons generated by the cathode are injected into the light-emitting layer, and the holes and the electrons are recombined in the light-emitting layer to generate excitons so that light emission is achieved
Data Source
AI summary
Provided are an organic compound and use thereof. The organic compound has a structure shown in Formula I. Through molecular structure design, the organic compound is endowed with suitable HOMO and LUMO energy levels, which is conducive to matching energy levels of compounds in adjacent layers and achieving efficient exciton recombination. The organic compound has small overlap of HOMO/LUMO energy level, high singlet energy level ES, high triplet energy level ET and small energy level difference ΔEST, which is conducive to reverse intersystem crossing and achieving higher luminescence efficiency. The organic compound molecule has high stability and low stacking degree, which is conducive to reducing concentration quenching and has excellent thermal and film stability. The organic compound is suitable as TADF materials, which is use for OLED devices, conducive to preparing OLED devices, can improve luminescence efficiency and stability of devices, reduce turn-on voltage and extend lifetime of devices.