OLED Emission Layer Cyclic Compound for Efficient Delayed Fluorescence

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Solution Overview

Problem

Current organic light-emitting devices (OLEDs) face limitations in achieving high efficiency and long lifespan due to chemical instability and steric hindrance issues, particularly in the emission layer where the distance between terminal rings affects resonance and reverse intersystem crossing.

Innovation Solution

Incorporating a condensed cyclic compound with a wide plate-like structure and a pentagonal ring at its core, which enhances electron delocalization, polarizability, and reduces steric hindrance, thereby improving resonance and reverse intersystem crossing, and is used in the emission layer of OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional emission layer materials are used, then device structure is simple, but efficiency and lifespan are limited due to chemical instability and steric hindrance

Engineering Contradiction:

Improvedevice efficiencyVSAvoidchemical stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the molecular structure parameters of the emission layer material by introducing a condensed cyclic compound with a wide plate-like structure and pentagonal ring core. This structural parameter change enhances electron delocalization and polarizability, improving efficiency while the specific molecular architecture provides chemical stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite molecular structure combining multiple rings (pentagonal ring at core with additional rings) to create a condensed cyclic compound. This composite structure achieves both high efficiency through enhanced electron delocalization and improved chemical stability through the rigid, extended framework.

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If terminal rings are positioned closer together, then device structure is compact, but resonance and reverse intersystem crossing are hindered due to steric hindrance

Engineering Contradiction:

Improvemolecular compactnessVSAvoidreverse intersystem crossing efficiency

Core Design Contradiction:

Volume of moving objectVSUse of energy by moving object

Solution Approach 1:

The patent transitions from a linear or planar arrangement to a three-dimensional wide plate-like structure with the pentagonal ring at the core. This dimensional change allows terminal rings to be positioned in different spatial orientations, reducing steric hindrance while maintaining appropriate distances for resonance and reverse intersystem crossing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The condensed cyclic compound with its wide plate-like structure and pentagonal ring core creates a curved, non-linear molecular geometry. This curvature reduces steric hindrance between terminal rings compared to linear arrangements, while the extended conjugated system maintains effective resonance and reverse intersystem crossing.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Use of energy by moving object

If condensed cyclic compound with wide plate-like structure is used, then resonance and reverse intersystem crossing are improved, but molecular complexity increases

Engineering Contradiction:

Improveresonance efficiencyVSAvoidmolecular structure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent concentrates the structural complexity in the core region (pentagonal ring) while keeping the overall molecular design focused and purposeful. The local quality of the condensed cyclic structure provides enhanced resonance and reverse intersystem crossing, while the rest of the molecular architecture remains relatively simple and functional.

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

This approach results in OLEDs with low driving voltage, high maximum quantum yield, and extended lifespan by activating multiple resonance structures and increasing the f-value of the condensed cyclic compound, making it a highly efficient material for delayed fluorescence.

Implementation Method 1

enhances electron delocalization, polarizability, and reduces steric hindrance

Methodology Applied

Scientific EffectElectron delocalization:

Implementation Method 2

activating multiple resonance structures and increasing the f-value of the condensed cyclic compound

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 3

Carriers, such as holes and electrons, recombine in the emission layer to produce excitons. These excitons transition (or relax) from an excited state to a ground state to thereby generate light.

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS12127475B2Light-emitting device including condensed cyclic compound and electronic apparatus including the light-emitting device

Publication Date: 2024.10.22 SAMSUNG DISPLAY CO LTD

AI summary

Provided are a light-emitting device including a condensed cyclic compound represented by Formula 1, and an electronic apparatus including the light-emitting device. The light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an interlayer between the first electrode and the second electrode and comprising an emission layer, wherein the light-emitting device further comprises a second capping layer outside the second electrode, the second capping layer having a refractive index of equal to or greater than 1.6, and the emission layer comprises at least one condensed cyclic compound represented by Formula 1.