TADF Aromatic Heterocyclic Compound for OLED Efficiency

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current OLED materials, particularly fluorescent and phosphorescent materials, face limitations in internal quantum yield and stability, while thermally activated delayed fluorescence (TADF) materials are scarce, necessitating the development of new TADF materials for efficient and cost-effective organic light-emitting diodes (OLEDs).

Innovation Solution

An aromatic heterocyclic compound with TADF properties is developed, featuring a specific chemical structure that includes electron donor and acceptor groups, optimizing the energy levels to facilitate reverse intersystem crossing and enhance luminescence efficiency, suitable for use in OLED light-emitting layers as a host or guest material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent materials are used in OLED light-emitting layer, then internal quantum yield can reach 100% and EQE can reach 20%, but production cost increases due to heavy metal complexes and device stability deteriorates under high current density

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 heavy metals (Ir, Pt, Os, Re, Ru) with organic TADF materials that are cheaper and do not require rare metal elements. The TADF materials achieve comparable internal quantum yield of 100% through reverse intersystem crossing mechanism, eliminating the need for costly phosphorescent complexes while maintaining high efficiency

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent modifies the energy level parameters of the organic compound by designing specific molecular structures with electron-donating and electron-withdrawing groups. By controlling the energy difference between S1 and T1 states to be less than 0.3 eV, the material enables efficient reverse intersystem crossing, achieving high internal quantum yield without heavy metals and improving device stability

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fluorescent materials are used in OLED light-emitting layer, then device structure is simple, but internal quantum yield does not exceed 25% due to spin-statistics limiting singlet exciton utilization

Engineering Contradiction:

Improvematerial structure complexityVSAvoidinternal quantum yield

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent implements a continuous cycle of intersystem crossing and reverse intersystem crossing between singlet and triplet exciton states. This continuous conversion allows both singlet and triplet excitons to contribute to light emission, achieving 100% internal quantum yield while maintaining relatively simple organic material structures without heavy metal complexes

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent designs composite molecular structures combining electron-donating groups and electron-withdrawing groups within a single organic molecule. This intramolecular charge transfer design creates the necessary energy level structure for TADF, achieving high internal quantum yield through a unified organic material rather than requiring complex device architectures

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 aromatic heterocyclic compound achieves high luminescence efficiency and improved external quantum efficiency in OLED devices, reducing production costs and enhancing stability, with the ability to emit red, green, or blue light, addressing the scarcity of TADF materials and efficiency issues in existing OLED technologies.

Implementation Method 1

when an energy level difference between the singlet excited state and the triplet excited state is relatively small, a reverse intersystem crossing (RISC) may occur among the molecules, and the excitons are converted from a T1 state to an S1 state by absorbing ambient heat

Methodology Applied

Scientific EffectThermally activated delayed fluorescence (TADF):

Implementation Method 2

a reverse intersystem crossing (RISC) may occur among the molecules, and the excitons are converted from a T1 state to an S1 state by absorbing ambient heat

Methodology Applied

Scientific EffectReverse intersystem crossing (RISC):

Implementation Method 3

The present disclosure relates to the technical field of organic electroluminescent materials

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11404648B2Aromatic heterocyclic compound and organic light-emitting display device

Publication Date: 2022.08.02 WUHAN TIANMA MICRO ELECTRONICS CO LTD

AI summary

The present disclosure provides an aromatic heterocyclic compound having property of thermally activated delayed fluorescence (TADF). The aromatic heterocyclic compound has a structure represented by Formula (I), in which X1 and X2 each is S, O, Se, or C; D is an electron donor, A is an electron acceptor; m is a number of the electron donor D, and the m electron donors D are the same or different; n is a number of the electron acceptor, and the n electron acceptors are the same or different; and m and n are 1 or 2. The aromatic heterocyclic compound provides a high luminescence efficiency. Organic light-emitting display devices including such aromatic heterocyclic compound have improved luminescence efficiency, lower cost and longer service life by using the aromatic heterocyclic compound as a light-emitting material, a host material, or a guest material.