Light-Emitting Device With Dual-Host Emission and Energy Blocking

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Solution Overview

Problem

Existing light-emitting devices face challenges in achieving low driving voltage, high luminescence efficiency, and long lifespan while maintaining excellent characteristics in terms of viewing angle, contrast ratio, and response speed.

Innovation Solution

Incorporating a first electrode, a second electrode, and an interlayer with a specific composition including a hole transport region and an emission layer containing a first host, a second host, and dopants, along with an electron-blocking layer having a compound with a lowest excited triplet energy less than 2.0 eV, which absorbs excess energy to prevent deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional emission layer materials are used, then device structure is simple, but luminescence efficiency is insufficient and lifespan is short

Engineering Contradiction:

Improveluminescence efficiencyVSAvoidemission layer composition complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The emission layer employs a composite material system comprising a host compound and a phosphorescent dopant compound. The host compound has a specific molecular structure with electron-transporting moieties and hole-transporting moieties, while the phosphorescent dopant is an organometallic complex with a transition metal and ligands. This composite approach enables efficient energy transfer from the host to the dopant, achieving high luminescence efficiency and extended device lifespan through synergistic material properties.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If driving voltage is reduced, then energy consumption decreases, but maintaining high luminescence efficiency becomes difficult

Engineering Contradiction:

Improvedriving voltageVSAvoidluminescence efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent optimizes the energy level parameters of the emission layer materials. The host compound is designed with specific HOMO and LUMO energy levels, and the phosphorescent dopant is selected with appropriate triplet energy levels. This parameter optimization enables efficient charge injection and carrier transport at low driving voltages while maintaining high luminescence efficiency through controlled energy transfer processes.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of stationary object

If emission layer materials are improved for higher efficiency, then lifespan increases, but material degradation from energy wastage becomes a problem

Engineering Contradiction:

Improvedevice lifespanVSAvoidmaterial degradation

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent addresses the harmful effect of energy wastage by incorporating the phosphorescent dopant with appropriate triplet energy levels. The dopant efficiently receives and utilizes triplet energy from the host, converting what would be wasteful non-radiative decay into useful photoluminescence emission. This energy utilization mechanism extends device lifespan by reducing thermal energy wastage that would otherwise cause material degradation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 results in a light-emitting device with low driving voltage, high luminescence efficiency, and extended lifespan by preventing energy wastage and reducing material degradation.

Implementation Method 1

the first dopant may be a phosphorescent dopant

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

the second dopant may be a fluorescent dopant or a delayed fluorescence dopant

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 3

the electron-blocking layer may include a compound having a lowest excited triplet energy (T1) less than 2.0 eV, and the compound of the electron-blocking layer may include an anthracene-naphthalene moiety and deuterium

Methodology Applied

Scientific EffectEnergy absorption: Absorption (EM radiation)

Data Source

PatentUS20250338769A1Light-emitting device, and electronic apparatus and electronic equipment including the light-emitting device

Publication Date: 2025.10.30 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 an interlayer between the first electrode and the second electrode, wherein the interlayer includes an emission layer, and a hole transport region between the first electrode and the emission layer. The emission layer includes a first host, a second host, a first dopant, and a second dopant; the first host is a hole-transporting compound; the second host is an electron-transporting compound; the first dopant is a phosphorescent dopant; the second dopant is a fluorescent dopant or a delayed fluorescence dopant; the hole transport region includes an electron-blocking layer adjacent to the emission layer; the electron-blocking layer includes a compound having a lowest excited triplet energy (T1) less than 2.0 eV, and the compound of the electron-blocking layer includes an anthracene-naphthalene moiety and deuterium.