Fluorescent OLED Compound Using rISC for Longer Device Life

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Solution Overview

Problem

Existing organic light-emitting devices (OLEDs) face issues with rapid compound deterioration due to long exciton lifetimes in phosphorescence and thermally activated delayed fluorescence (TADF), leading to shorter device lifetimes and high production costs from the use of expensive metals like iridium and platinum.

Innovation Solution

A light-emitting device incorporating a fluorescent compound with a specific electronic state condition, utilizing reverse intersystem crossing (rISC) and reverse internal conversion (IC) processes to achieve a ratio of rISC to IC rates greater than 0.5, enabling efficient fluorescence emission without expensive transition metals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If phosphorescent compounds or TADF compounds are used in OLEDs, then high luminescence efficiency can be achieved, but exciton lifetime becomes long causing rapid compound deterioration and shorter device lifetime

Engineering Contradiction:

Improveluminescence efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

Loss of energyVSDuration of action of stationary object

Solution Approach 1:

The patent changes the electronic state parameters of the fluorescent compound by introducing a 3n-π* excited state and controlling the energy levels and spin-orbit coupling to achieve appropriate rISC and IC rates, thereby reducing exciton lifetime while maintaining high luminescence efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the phosphorescence or TADF emission mechanism with a fluorescent emission mechanism that utilizes reverse intersystem crossing from a 3n-π* state, fundamentally changing the emission pathway to achieve short exciton lifetime and high efficiency simultaneously

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If phosphorescent compounds containing iridium or platinum are used, then high luminescence efficiency can be achieved, but production costs increase significantly due to expensive metals

Engineering Contradiction:

Improveluminescence efficiencyVSAvoidproduction cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive fluorescent compounds without expensive transition metals like iridium or platinum, replacing costly materials with cheaper organic compounds that achieve comparable or superior performance through the 3n-π*-to-1π-π* rISC mechanism

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts and eliminates the expensive metal components from the emission layer by using pure organic fluorescent compounds, removing the source of high production costs while maintaining emission functionality through molecular design

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If conventional fluorescent compounds are used, then device simplicity is maintained, but luminescence efficiency is insufficient compared to phosphorescent compounds

Engineering Contradiction:

Improvecompound structure simplicityVSAvoidluminescence efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent modifies the electronic state parameters of conventional fluorescent compounds by introducing or enhancing the 3n-π* excited state and controlling the energy level differences and spin-orbit coupling values to achieve high rISC rates and improved luminescence efficiency while maintaining the fluorescent emission mechanism

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 fluorescent compound enhances luminescence efficiency and extends device lifespan while reducing production costs, offering high luminescence efficiency and improved performance characteristics.

Implementation Method 1

excitons in a 3n-π* excited state of the fluorescent compound may migrate to a 1π-π* excited state of the fluorescent compound by reverse intersystem crossing (rISC) having a Rate (rISC)

Methodology Applied

Scientific EffectReverse intersystem crossing (rISC):

Implementation Method 2

excitons in the 3n-π* excited state of the fluorescent compound may migrate to a 3π-π* excited state of the fluorescent compound through reverse internal conversion (IC) having a Rate (IC)

Methodology Applied

Scientific EffectReverse internal conversion (IC):

Implementation Method 3

the excitons in the 1π-π* excited state undergo radiative transition to a ground state to emit light via fluorescence

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS12604661B2Light-emitting device including fluorescent compound, electronic apparatus including light-emitting device, and fluorescent compound

Publication Date: 2026.04.14 SAMSUNG ELECTRONICS CO LTD

AI summary

A light-emitting device including an organic layer disposed between a first electrode and a second electrode, the organic layer comprising a fluorescent compound, wherein upon excitation, excitons in a 3n-π* excited state of the fluorescent compound migrate to a 1π-π* excited state of the fluorescent compound by reverse intersystem crossing with a Rate (rISC), and then undergo radiative transition to a ground state to emit light via fluorescence. The fluorescent compound is defined by a ratio of Rate (rISC) to Rate (IC) is 0.5 or greater. An electronic apparatus including the light-emitting device, and the fluorescent compound.