Host Material for Phosphorescent OLEDs

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current organic electroluminescence devices face challenges in achieving high efficiency and long lifetime due to the degradation of host materials, particularly those used in phosphorescent emitting layers, which suffer from short lifetimes and inefficient energy transfer to phosphorescent dopants.

Innovation Solution

The use of specific host materials represented by Formulas (1), (3), and (4), which include condensed aromatic hydrocarbon rings, enhances the stability and triplet energy gap, allowing efficient energy transfer to phosphorescent dopants and extending the device's lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CBP is used as a host material, then luminous efficiency is markedly enhanced, but the device lifetime becomes too short for practical use

Engineering Contradiction:

Improveluminous efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical structure parameters of the host material from CBP to compounds with condensed aromatic hydrocarbon rings (such as dibenzofuran, dibenzothiophene, dithienosilole units). This structural modification increases oxidation stability while maintaining sufficient triplet energy (2.1-2.8 eV), thereby resolving the contradiction between high luminous efficiency and long device lifetime.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If anthracene derivatives are used as a host material, then the molecular structure is simple, but excited triplet energy is too small to transfer energy to phosphorescent dopants

Engineering Contradiction:

Improvemolecular structure complexityVSAvoidexcited triplet energy

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent employs composite molecular structures combining condensed aromatic hydrocarbon rings (dibenzofuran, dibenzothiophene, dithienosilole) with electron-donating or electron-withdrawing groups. This composite approach increases excited triplet energy to 2.1-2.8 eV while maintaining reasonable structural complexity, enabling effective energy transfer to phosphorescent dopants.

Inventive Principle:

Principle #40Composite materials

3Productivity

If condensed-ring derivatives with nitrogen-containing rings are used as host material, then luminous efficiency and lifetime are improved, but practical application remains unsatisfactory

Engineering Contradiction:

Improveluminous efficiencyVSAvoidpractical applicability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality modification by introducing electron-donating groups (alkyl, alkoxy, amino) or electron-withdrawing groups (cyano, carbonyl, sulfone) at specific positions of the condensed aromatic hydrocarbon ring system. This localized functional group substitution optimizes both luminous efficiency and device reliability for practical applications.

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

These host materials enable the formation of phosphorescent organic electroluminescence devices with high efficiency and long lifetime by stabilizing the molecular structure and optimizing energy transfer, leading to improved luminance intensity and extended device lifespan.

Implementation Method 1

exciton energy of the produced excitons is transferred to the dopant, so that light can be emitted from the dopant with high efficiency

Methodology Applied

Scientific EffectEnergy transfer:

Implementation Method 2

phosphorescent materials that emit light using a triplet exciton

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 3

an organic thin-film layer between an anode and a cathode, the organic thin-film layer including an emitting layer, and such an organic EL device emits light using exciton energy produced by recombination of holes with electrons

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8330350B2Organic electroluminescence device and material for organic electroluminescence device

Publication Date: 2012.12.11 IDEMITSU KOSAN CO LTD

AI summary

An organic electroluminescence device includes: a cathode; an anode; and a single-layered or multilayered organic thin-film layer provided between the cathode and the anode. In the organic electroluminescence device, the organic thin-film layer includes at least one emitting layer, and the at least one emitting layer includes at least one phosphorescent material and a host material represented by the following Formula (1).Ra—Ar1—Ar2—Rb (1)In Formula (1):Ra and Rb each represent a substituted or non-substituted benzene ring or a substituted or non-substituted condensed aromatic hydrocarbon ring selected from a group consisting of a naphthalene ring, a chrysene ring, a fluoranthene ring, a triphenylene ring, a phenanthrene ring, a benzophenanthrene ring, a dibenzophenanthrene ring, a benzotriphenylene ring, a benzochrysene ring and a picene ring; andAr1 and Ar2 each represent a substituted or non-substituted benzene ring or a substituted or non-substituted condensed aromatic hydrocarbon ring selected from a group consisting of a naphthalene ring, a chrysene ring, a fluoranthene ring, a triphenylene ring, a benzophenanthrene ring, a dibenzophenanthrene ring, a benzotriphenylene ring, a benzochrysene ring and a picene ring.