OLED Emissive Layer Material Combination for Efficiency and Lifetime

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Solution Overview

Problem

Current phosphorescent OLEDs face challenges with non-saturated blue color, short device lifetime, high operating voltage, and efficiency roll-off at high brightness, limiting their performance and commercialization.

Innovation Solution

An electroluminescent device utilizing a novel material combination comprising a first metal complex and a first compound, specifically designed for the emissive layer, which includes a ligand La coordinated with a metal of relative atomic mass greater than 40, and a compound structure that enhances the device's performance by achieving a darker red color, lower voltage, and higher efficiency while extending the device's lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent emitters are used in OLEDs, then internal quantum efficiency can reach 100%, but device lifetime becomes short and operating voltage becomes high

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of moving object

Solution Approach 1:

The patent modifies the molecular structure of phosphorescent emitters by introducing specific ligand configurations and metal complexes (e.g., Ir(III) complexes with cyclometalating ligands), changing the photophysical parameters to achieve both high efficiency and long lifetime simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite phosphorescent systems combining multiple ligands and metal centers (e.g., Ir(III) with cyclometalating ligands and auxiliary ligands like picolinate or acetylacetonate) to create emitters that simultaneously achieve high internal quantum efficiency and extended device lifetime

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If phosphorescent emitters are used in OLEDs, then internal quantum efficiency can reach 100%, but operating voltage becomes high

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoidoperating voltage

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent optimizes the HOMO-LUMO energy levels of phosphorescent emitters through ligand design, adjusting the energy parameters to reduce operating voltage while maintaining high internal quantum efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces host-guest systems where the host material acts as an intermediary, facilitating charge transport and exciton management to reduce operating voltage while preserving the high efficiency benefits of phosphorescent emitters

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If conventional phosphorescent OLEDs are used, then efficiency can be achieved, but efficiency roll-off occurs at high brightness

Engineering Contradiction:

Improveluminous efficiencyVSAvoidbrightness

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent employs delayed fluorescence mechanisms where triplet excitons undergo reverse intersystem crossing to singlet states, creating a periodic emission pattern that reduces efficiency roll-off at high brightness while maintaining high luminous efficiency

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent modifies the photophysical parameters of phosphorescent emitters by adjusting ligand fields and metal centers to optimize the balance between phosphorescence and delayed fluorescence, reducing efficiency roll-off at high brightness

Inventive Principle:

Principle #35Parameter changes

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 novel material combination enables the electroluminescent device to produce a darker red color, operate at lower voltage, and exhibit higher efficiency and longer lifetime, thereby improving overall device performance.

Implementation Method 1

an electroluminescent device, comprising: an anode, a cathode, and an organic layer disposed between the anode and the cathode

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

phosphorescent OLED, which uses triplet emission from heavy metal containing complexes as the emitter

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS20220216433A1Electroluminescent device

Publication Date: 2022.07.07 BEIJING SUMMER SPROUT TECH CO LTD

AI summary

Provided is an electroluminescent device. The electroluminescent device includes an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer includes a first metal complex of a ligand having a structure represented by Formula 1 and a first compound having a structure represented by Formula 2. The novel material combination comprising the first metal complex and the first compound can be used in an emissive layer in an electroluminescent device. The novel material combination can enable the novel electroluminescent device to obtain a darker red color, a lower voltage, higher efficiency, and a longer lifetime and can provide better device performance. Further provided are an electronic device and a compound combination.