Polycyclic Compound with Azagermine Group for TADF OLEDs

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Solution Overview

Problem

Current organic electroluminescence devices face challenges in reducing driving voltage and increasing device lifespan for efficient light emission.

Innovation Solution

A polycyclic compound represented by Formula 1 is used in the emission layer of an organic electroluminescence device, incorporating an azagermine group with a heavy atom Ge as an electron donor, enhancing spin orbit coupling to promote singlet-triplet intersystem crossing and facilitate thermally activated delayed fluorescence (TADF) without triplet exciton energy loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional organic electroluminescence devices are used, then light emission is achieved, but driving voltage is high and device lifespan is limited

Engineering Contradiction:

Improvedevice lifespanVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the chemical composition parameters of the emission layer by incorporating a polycyclic compound with specific structural features (Formula 1) containing an azagermine group. This compound has optimized HOMO-LUMO energy levels and electron mobility characteristics, which directly alter the electrical parameters of the device, enabling lower driving voltage and extended operational lifespan without sacrificing light emission performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite emission layer material system combining the polycyclic compound (Formula 1) with host materials and dopants. This composite approach allows synergistic effects where the polycyclic compound provides efficient charge transport and long-lived excited states, while host materials provide structural stability and additional emission pathways, collectively improving both device lifespan and reducing operational voltage requirements.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If triplet excitons are utilized for light emission, then emission efficiency can be improved, but energy loss occurs due to triplet exciton decay

Engineering Contradiction:

Improveemission efficiencyVSAvoidtriplet exciton energy loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent converts the traditionally harmful triplet exciton decay pathway into a beneficial emission mechanism through thermally activated delayed fluorescence (TADF). The polycyclic compound's heavy atom effect enhances spin-orbit coupling, enabling efficient reverse intersystem crossing from triplet to singlet states. This allows triplet excitons, which would normally represent energy loss, to be converted into light-emitting singlet excitons, achieving high emission efficiency while minimizing energy waste.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent modifies the energy level parameters and spin dynamics of the emission layer by introducing the polycyclic compound with specific electronic structure. The compound's small singlet-triplet energy gap (ΔEST) and enhanced spin-orbit coupling constant (through heavy atom Ge) fundamentally change the exciton utilization parameters, enabling efficient thermal activation from triplet to singlet states and converting non-emissive triplet excitons into productive light-emitting states.

Inventive Principle:

Principle #35Parameter changes

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 polycyclic compound achieves high emission efficiency and extended device life by efficiently utilizing the heavy atom effect to enable TADF, improving both performance and longevity of the organic electroluminescence device.

Implementation Method 1

incorporating an azagermine group with a heavy atom Ge as an electron donor, enhancing spin orbit coupling to promote singlet-triplet intersystem crossing

Methodology Applied

Scientific EffectSpin orbit coupling:

Implementation Method 2

facilitate thermally activated delayed fluorescence (TADF) without triplet exciton energy loss

Methodology Applied

Scientific EffectThermally activated delayed fluorescence:

Implementation Method 3

The organic electroluminescence device emits light using light emitted during the transition of the excitons back to a ground state

Methodology Applied

Scientific EffectLight emission during exciton transition: Luminescence

Data Source

PatentUS11254694B2Polycyclic compound and organic electroluminescence device including the same

Publication Date: 2022.02.22 SAMSUNG DISPLAY CO LTD

AI summary

A polycyclic compound and an organic electroluminescence device including the same, the polycyclic compound being represented by Formula 1: