Purely Organic TADF Molecules for Stable Blue and Green OLEDs

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Solution Overview

Problem

Existing organic optoelectronic devices face challenges in achieving high efficiency and stability, particularly in the blue and green spectral regions, with known emitter materials limiting performance and stability.

Innovation Solution

Development of purely organic molecules without metal ions, exhibiting thermally activated delayed fluorescence (TADF) and high photoluminescence quantum yields, specifically designed for use in organic light-emitting diodes (OLEDs), which are stable during vapor deposition and have emissions in the blue, sky blue, or green spectral regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If metal complexes are used as emitter materials in OLEDs, then device efficiency can be improved, but device stability and lifetime deteriorate

Engineering Contradiction:

Improvedevice efficiencyVSAvoiddevice stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent removes metal ions from the emitter material composition entirely, extracting the harmful element (metal) while retaining the desired optical properties through purely organic molecules. This resolves the contradiction by eliminating the source of instability while maintaining efficiency through TADF mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite organic molecule structures combining electron-donating units (carbazole, triphenamine) with electron-accepting units (triazine, pyrimidine) to create molecules with optimized HOMO-LUMO gaps and high photoluminescence quantum yields, achieving both efficiency and stability without metals.

Inventive Principle:

Principle #40Composite materials

2Productivity

If traditional emitter materials are used in blue and green spectral regions, then device performance can be improved, but device lifetime deteriorates

Engineering Contradiction:

Improvedevice performanceVSAvoiddevice lifetime

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent systematically adjusts molecular parameters including HOMO-LUMO energy gaps, photoluminescence quantum yields, and emission wavelengths by modifying molecular structures (e.g., different carbazole substitutions, triazine ring variations) to optimize both performance and lifetime simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If purely organic molecules without metal ions are used, then device stability is improved, but achieving high efficiency in blue and green regions becomes difficult

Engineering Contradiction:

Improvedevice stabilityVSAvoiddevice efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces metal-centered photophysics with organic molecular photophysics, substituting the emission mechanism from metal-to-ligand charge transfer (MLCT) to thermally activated delayed fluorescence (TADF) through carefully designed HOMO-LUMO energy level alignments in organic molecules.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

These organic molecules enhance the efficiency and stability of OLEDs, offering higher performance and longer lifetimes compared to devices using traditional emitter materials while maintaining comparable color characteristics.

Implementation Method 1

The molecules according to the invention especially exhibit thermally activated delayed fluorescence (TADF)

Methodology Applied

Scientific EffectThermally activated delayed fluorescence (TADF): Photoluminescence

Implementation Method 2

more particularly are stable on vapour deposition within the context of production of an optoelectronic device (for example of an OLED)

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentUS10421746B2Organic molecules, especially for use in organic optoelectronic devices

Publication Date: 2019.09.24 SAMSUNG DISPLAY CO LTD

AI summary

The invention relates to an organic molecule, especially for use in optoelectronic components. According to the invention, the organic molecule containsa first chemical unit having a structure of formula Ianda second chemical unit having a structure of formula IIwhere the first chemical unit is joined to the second chemical unit via a single bond;where the following definitions apply:V is an attachment point of the single bond between the first chemical unit of formula I and the chemical unit or selected from the group consisting of R2, CN;V is H or an attachment point of the single bond between the first chemical unit of formula I and the chemical unit;T and W are each an attachment point of the single bond between the first chemical unit and the second chemical unit or selected from the group consisting of R2, CN;X and Y are each selected from the group consisting of R2 and CN.