Polycyclic Compound for Blue OLED Efficiency and Color Purity

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Solution Overview

Problem

There is a demand for organic electroluminescence devices with low driving voltage, high emission efficiency, and long lifespan, particularly in the short wavelength region, where existing materials struggle to achieve high color purity and stability.

Innovation Solution

A polycyclic compound represented by Formula 1 is used in the organic electroluminescence device, which includes an emission layer that emits thermally activated delayed fluorescence, specifically designed to emit blue light with a central wavelength of about 470 nanometers or less, utilizing a structure with a first and second electrode and multiple functional layers, including a hole transport region and an electron transport region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If existing materials are used in the short wavelength region, then device structure can be maintained, but emission efficiency and color purity are insufficient

Engineering Contradiction:

Improveemission efficiencyVSAvoidcolor purity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent modifies molecular parameters of the polycyclic compound including introducing electron-accepting groups (cyano, fluoro, trifluoromethyl) at specific positions, adjusting HOMO-LUMO energy levels, and optimizing molecular structure to achieve both high emission efficiency and color purity in the blue light region with wavelength of 470 nm or less

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite material design by combining the polycyclic compound with electron-transporting materials (e.g., Alq3, BCP, TPBi) and hole-transporting materials (e.g., TCTA, TAPC) to create a multi-layer emission layer structure that achieves both high emission efficiency and color purity through synergistic effects of different materials

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If driving voltage is reduced, then energy consumption decreases, but emission efficiency may be compromised

Engineering Contradiction:

Improvedriving voltageVSAvoidemission efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent optimizes energy level parameters of the polycyclic compound to achieve appropriate HOMO-LUMO gap and energy level alignment with adjacent layers, enabling low driving voltage operation while maintaining high emission efficiency through enhanced charge injection and transport

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces traditional high-voltage electrical excitation with thermally activated delayed fluorescence mechanism, where thermal energy assists in harvesting triplet excitons and converting them to singlet excitons for light emission, thereby achieving high efficiency at low driving voltages

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If emission efficiency is increased, then device performance improves, but lifespan may be reduced

Engineering Contradiction:

Improveemission efficiencyVSAvoidlifespan

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes molecular stability parameters of the polycyclic compound including introducing stable electron-accepting groups, optimizing molecular packing, and enhancing resistance to photo-oxidation and electrochemical degradation, thereby achieving both high emission efficiency and long device lifespan

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention incorporates stabilizing substituents (cyano, fluoro, trifluoromethyl groups) at strategic positions in advance to prevent molecular degradation and aggregation-caused quenching during device operation, cushioning against efficiency roll-off and material degradation over time

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 enhances emission efficiency and color purity, achieving long-lasting performance with reduced driving voltage, specifically improving blue light emission in organic electroluminescence devices.

Implementation Method 1

at least one functional layer of the plurality of functional layers includes the polycyclic compound... the emission layer that emits thermally activated delayed fluorescence

Methodology Applied

Scientific EffectThermally activated delayed fluorescence: Fluorescence

Data Source

PatentUS11844272B2Organic electroluminescence device and polycyclic compound for organic electroluminescence device

Publication Date: 2023.12.12 SAMSUNG DISPLAY CO LTD

AI summary

An organic electroluminescence device of an embodiment includes a first electrode, a second electrode, and a plurality of functional layers disposed between the first electrode and the second electrode, wherein at least one functional layer of the plurality of functional layers includes a polycyclic compound represented by Formula 1, thereby showing excellent light emitting efficiency in a short wavelength region: