TADF Organic Compound for OLED Luminous Efficiency

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Solution Overview

Problem

Current TADF materials for OLED devices face challenges in achieving high-performance luminescence properties, stability, and cost-effectiveness, with limited options available and inefficiencies in light-emitting mechanisms.

Innovation Solution

An organic compound with a specific molecular structure, featuring an electron donor unit, an electron acceptor unit, and a bridging portion with large steric hindrance, is designed to reduce the energy level difference between singlet and triplet states, enabling balanced radiative transitions and improved carrier transport, suitable for use as a light-emitting layer material in OLED devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent material is used to achieve high internal quantum yield, then the EQE can reach 20%, but the production cost is high and stability is poor

Engineering Contradiction:

Improveinternal quantum yieldVSAvoiddevice stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent replaces expensive phosphorescent materials containing rare metals (Ir, Pt, Os, Re, Ru) with organic TADF materials that have shorter lifetimes but achieve comparable or superior performance through reverse intersystem crossing mechanisms, significantly reducing production cost while maintaining device stability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent modifies molecular parameters by designing specific organic compound structures with appropriate HOMO-LUMO energy gaps and spin-orbit coupling characteristics to enable efficient reverse intersystem crossing, achieving high internal quantum yield without heavy metals and improving device stability through optimized molecular design

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If fluorescent material is used, then the production cost is low, but the maximum internal quantum yield is not greater than 25%

Engineering Contradiction:

Improveproduction costVSAvoidinternal quantum yield

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent introduces triplet excitons as an intermediary state that can be converted to singlet excitons through reverse intersystem crossing, allowing the material to utilize both singlet (25%) and triplet (75%) excitons for light emission, thereby achieving near-100% internal quantum yield while maintaining the cost advantages of organic materials

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent designs composite molecular structures combining electron-donating groups and electron-accepting groups with specific spatial arrangements to create TADF emitters that exhibit both cost-effectiveness of organic materials and high efficiency through enhanced spin-orbit coupling and optimized energy level alignment

Inventive Principle:

Principle #40Composite materials

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 enhances the luminous efficiency, reduces drive voltage and energy consumption, and prolongs the device's working life by achieving high light-emitting quantum efficiency and balanced mobility, while being environmentally friendly and cost-effective.

Implementation Method 1

reverse intersystem crossing (RISC) occurs within molecules at a certain temperature, and the exciton of T1 state is converted to the S1 state by absorbing ambient heat

Methodology Applied

Scientific EffectReverse intersystem crossing (RISC):

Implementation Method 2

the exciton of T1 state is converted to the S1 state by absorbing ambient heat and then decays from the S1 state to the ground state S0

Methodology Applied

Scientific EffectThermally activated delayed fluorescent (TADF):

Implementation Method 3

the singlet excited state S1 of the fluorescent material returns to the ground state S0 through radiative transition

Methodology Applied

Scientific EffectRadiative transition: Luminescence

Implementation Method 4

Due to the heavy atom effect, intersystem crossing within molecules can be strengthened through spin coupling

Methodology Applied

Scientific EffectHeavy atom effect:

Implementation Method 5

The triplet excited state T1 of the phosphorescent material directly decays to the ground state S0

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS20220093862A1Organic compound and application thereof

Publication Date: 2022.03.24 WUHAN TIANMA MICRO ELECTRONICS CO LTD

AI summary

Provided are an organic compound and an application thereof. The organic compound has a structure as shown in Formula I. The overlap degree between HOMO and LUMO is effectively reduced through structural framework design and specific group introduction, thus the energy level difference between the triplet state and the singlet state is reduced to below 300 meV, the reverse crossing of the energy from the triplet to the singlet is satisfied. The organic compound obtains a relatively balanced radiative transition rate and good TADF characteristics, and has excellent carrier transport performance, balance and stability of electron mobility and hole mobility, low preparation cost, and environmental friendliness. The organic compound can be used as a light-emitting layer material of an OLED device, and the material has a TADF light-emitting mechanism and high light-emitting quantum efficiency, which can reduce the drive voltage and energy consumption, and improve luminous efficiency and working life.