OLED Enhancement Layer for Short Triplet Emitter Lifetime

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Solution Overview

Problem

Existing OLEDs using phosphorescent emitters typically demonstrate relatively long excited state lifetimes, which can lead to device aging and performance degradation due to triplet emission from the vacuum level.

Innovation Solution

The OLED device incorporates an anode, a cathode, and an organic layer, with an enhancement layer to reduce the transient excited state lifetime of the emitter to 200 ns or less and thus reduce the device aging rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent emitters are used in OLEDs, then light emission efficiency is improved, but excited state lifetime becomes too long causing device aging

Engineering Contradiction:

Improvelight emission efficiencyVSAvoidexcited state lifetime

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

The patent introduces an enhancement layer as an intermediary component between the emitter and the substrate. This enhancement layer modifies the photonic environment to accelerate the radiative decay rate of the emitter, reducing excited state lifetime from microseconds to 200 ns or less while preserving phosphorescent emission efficiency. The enhancement layer acts as a mediator that couples the emitter to the substrate, enabling faster energy dissipation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the photonic density of states parameter by introducing the enhancement layer with specific optical properties. This parameter change increases the radiative decay rate constant, thereby reducing the excited state lifetime. The enhancement layer modifies the local photonic environment to achieve faster emission decay without sacrificing quantum efficiency.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If emitter is placed close to substrate, then excited state lifetime is reduced to 200 ns or less, but device structure becomes more complex

Engineering Contradiction:

Improveexcited state lifetimeVSAvoiddevice structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines the enhancement layer with the substrate structure, merging two functional elements into a unified device architecture. The enhancement layer is positioned so closely to the emitter that it becomes an integral part of the emission cavity, reducing the need for separate lifetime control mechanisms while achieving the desired 200 ns or less excited state lifetime.

Inventive Principle:

Principle #5Merging (Combining)

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 OLED device achieves improved lifetimes by incorporating the emitter within a threshold distance of the enhancement layer to reduce the transient excited state lifetime to 200 ns or less and thus reduce the device aging rate.

Implementation Method 1

increases the photonic density of states of the OLED device. The increased photonic density of states increases a radiative decay rate constant of the emitter

Methodology Applied

Scientific EffectPurcell effect:

Data Source

PatentEP3709376B1OLED with triplet emitter and excited state lifetime less than 200 ns

Publication Date: 2025.12.10 UNIVERSAL DISPLAY CORP

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AI summary

Emissive devices are provided that include a phosphorescent emitter placed within a threshold distance of an enhancement layer to achieve transient lifetimes of 200 ns or less.