Donor-Acceptor OLED Compounds for TADF Efficiency

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Solution Overview

Problem

Conventional OLEDs face challenges in achieving optimal performance due to limitations in internal quantum efficiency and the need for materials that can efficiently emit delayed fluorescence, particularly in achieving high efficiency beyond the 25% spin statistics limit.

Innovation Solution

Development of compounds with specific configurations of donor and acceptor groups that enable E-type delayed fluorescence, allowing for the spatial separation of HOMO and LUMO, which facilitates thermally activated delayed fluorescence (TADF) emission, thereby exceeding the spin statistics limit for internal quantum efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional OLED materials are used, then device fabrication is straightforward, but internal quantum efficiency is limited to 25% due to spin statistics

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoidenergy loss from non-emissive triplet states

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent modifies molecular parameters by designing compounds with specific donor-acceptor group configurations and spatial arrangements. This changes the electronic structure parameters (HOMO-LUMO distribution, singlet-triplet energy gap) to enable thermally activated delayed fluorescence, allowing triplet excitons to be converted to singlet states for light emission, thereby exceeding the 25% spin statistics limit

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite molecular structures combining electron-donor groups and electron-acceptor groups in specific spatial configurations. These composite organic compounds work together with host materials and dopants to create a system that facilitates efficient energy transfer and TADF emission, achieving high internal quantum efficiency

Inventive Principle:

Principle #40Composite materials

2Productivity

If materials with spatially separated HOMO and LUMO are designed, then TADF emission efficiency is enhanced, but molecular design and synthesis complexity increases

Engineering Contradiction:

ImproveTADF emission efficiencyVSAvoidmolecular design complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the molecular structure into distinct functional segments: electron-donor groups (such as carbazole, triphen胺) and electron-acceptor groups (such as triazine, pyridine). These segmented units are connected through linkers in specific spatial arrangements, allowing independent optimization of each segment's properties while achieving the desired overall TADF behavior through their interaction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating specific spatial configurations where donor and acceptor groups are positioned at defined distances and orientations relative to each other. This local structural arrangement optimizes the overlap of HOMO and LUMO wavefunctions in specific regions while maintaining spatial separation, thereby controlling the singlet-triplet energy gap and enabling efficient TADF at specific molecular locations

Inventive Principle:

Principle #3Local quality

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 use of these compounds in OLEDs enhances internal quantum efficiency beyond conventional limits, achieving higher efficiency and improved performance by enabling efficient TADF emission.

Implementation Method 1

Methodology Applied

Scientific EffectThermally activated delayed fluorescence (TADF):

Implementation Method 2

The use of these compounds in OLEDs enhances internal quantum efficiency beyond conventional limits, achieving higher efficiency and improved performance by enabling efficient TADF emission.

Methodology Applied

Scientific EffectReverse intersystem crossing:

Implementation Method 3

OLEDs make use of thin organic films that emit light when voltage is applied across the device.

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20200144512A1Organic electroluminescent materials and devices

Publication Date: 2020.05.07 UNIVERSAL DISPLAY CORP

AI summary

Novel compounds including at least two donor groups GD and at least two acceptor groups GA are disclosed. In these compounds, each donor group GD and acceptor group GA can be the same or different; any pair of donor groups GD is separated by at least one acceptor group GA; any pair of acceptor groups GA is separated by at least one donor group GD; and the total number of the donor groups GD is equal to the total number of the acceptor groups GA. Organic light emitting devices, consumer products, formulations, and chemical structures containing the compounds are also disclosed.