Polycyclic Compound Emission Layer for OLED Efficiency and Lifespan

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Solution Overview

Problem

Current organic electroluminescence display devices face challenges in achieving low driving voltage, high luminous efficiency, and long service life, particularly in developing materials that consistently meet these criteria for efficient light emission.

Innovation Solution

A light emitting device is designed with a polycyclic compound incorporated into the emission layer, utilizing specific functional layers and compounds represented by Formulas 1, HT, ET, and PS, which enhance luminous efficiency and service life by optimizing the recombination of holes and electrons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional materials are used in the emission layer, then device structure is simple, but luminous efficiency and service life are insufficient

Engineering Contradiction:

Improveservice lifeVSAvoidmaterial composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The emission layer uses a composite material system comprising a host compound (Formula 1) and a polycyclic compound (Formula 3) as dopant. The host compound contains specific heteroatom groups (X1 and X2 being N(R12), S, or O) that facilitate charge carrier recombination, while the polycyclic compound enhances luminescence efficiency. This composite approach resolves the contradiction by achieving high reliability through synergistic material combination rather than relying on a single material.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes specific molecular parameters of the compounds used in the emission layer, including the heteroatom composition (X1, X2, Y1, Y2 being N, S, or O), ring structures (n1, n2, n3, n4 being integers from 0 to 7), and substituent groups (R1 to R18). By precisely controlling these chemical parameters, the patent achieves improved service life and luminous efficiency while maintaining a manageable material structure.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If materials optimized for high luminous efficiency are used, then light emission performance improves, but driving voltage increases

Engineering Contradiction:

Improveluminous efficiencyVSAvoiddriving voltage

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent introduces specific functional groups at localized positions within the molecular structure to achieve energy optimization. The heteroatoms (X1, X2, Y1, Y2 being N, S, or O) are positioned at specific locations in the molecular framework to facilitate efficient charge carrier recombination and energy transfer. This localized functional group placement enables high luminous efficiency without requiring excessive driving voltage, as the energy conversion occurs efficiently at specific molecular sites rather than requiring high overall energy input.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If simple emission materials are used, then manufacturing is easier, but luminous efficiency is insufficient

Engineering Contradiction:

Improvematerial processing easeVSAvoidluminous efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The host compound (Formula 1) is designed with multi-functional characteristics that perform multiple roles simultaneously: it serves as the matrix material, facilitates charge carrier transport, enables energy transfer to the dopant, and provides structural stability. The polycyclic compound (Formula 3) similarly provides multiple functions including enhancing luminescence, improving charge carrier recombination, and stabilizing the emission layer structure. This multi-functionality reduces the need for additional separate materials and processing steps, maintaining ease of manufacture while achieving high luminous efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution improves luminous efficiency and extends the service life of light emitting devices by effectively recombining charge carriers, leading to enhanced light emission characteristics.

Implementation Method 1

delayed fluorescence emission, which uses the generating phenomenon of singlet excitons by the collision of triplet excitons (triplet-triplet annihilation, TTA)

Methodology Applied

Scientific EffectTriplet-triplet annihilation (TTA):

Implementation Method 2

delayed fluorescence emission, which uses the generating phenomenon of singlet excitons by the collision of triplet excitons

Methodology Applied

Scientific EffectDelayed fluorescence:

Implementation Method 3

Development is currently directed to a material for thermally activated delayed fluorescence (TADF) using delayed fluorescence phenomenon

Methodology Applied

Scientific EffectThermally activated delayed fluorescence (TADF):

Data Source

PatentUS20240180033A1Light emitting device and polycyclic compound for the same

Publication Date: 2024.05.30 SAMSUNG DISPLAY CO LTD

AI summary

Embodiments provide a light emitting device that includes a first electrode, a second electrode facing the first electrode, and at least one functional layer disposed between the first electrode and the second electrode, wherein the at least one functional layer includes a first compound represented by Formula 1, and at least one of a second compound represented by Formula HT or a third compound represented by Formula ET, thereby exhibiting low voltage, high efficiency, and long service life characteristics. Formulas 1, HT, and ET are each explained in the specification.