Light-Emitting Layer for Simultaneous Fluorescence and Phosphorescence

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Solution Overview

Problem

Existing light-emitting devices face challenges in efficiently utilizing both singlet and triplet excitation energies from a host material, as excitation energy is often transferred to guest materials with lower energy levels, inhibiting simultaneous emission from fluorescent and phosphorescent substances.

Innovation Solution

Incorporating a light-emitting layer with a first organic compound that converts singlet excitation energy into light emission and a second organic compound that converts triplet excitation energy into light emission, using protecting groups to inhibit energy transfer by the Dexter mechanism and maintain efficient energy transfer by the Förster mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a plurality of guest materials are used in an EL layer, then the energy utilization from host material can be improved, but the excitation energy is transferred to materials with lower energy levels, making it difficult to concurrently obtain light emission from both fluorescent and phosphorescent substances

Engineering Contradiction:

Improveenergy utilization efficiencyVSAvoidsimultaneous emission capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by carefully controlling the energy levels (S1 and T1 levels) of guest materials relative to the host material. By selecting fluorescent and phosphorescent substances with appropriate energy level differences, the patent enables selective energy transfer pathways that allow simultaneous emission from both types of materials, resolving the contradiction between energy utilization and simultaneous emission capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs local quality by using different types of guest materials (fluorescent and phosphorescent substances) with distinct local properties in the EL layer. Each material type is positioned and configured to receive specific types of excitation energy (singlet or triplet), allowing localized energy conversion and simultaneous light emission from different regions or components within the light-emitting layer.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If the triplet excitation level of fluorescent substance is used, then it serves as a deactivation pathway of triplet excitation energy, but this prevents efficient emission from phosphorescent substance or TADF material

Engineering Contradiction:

Improvetriplet excitation energy deactivationVSAvoidphosphorescence emission efficiency

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent resolves this contradiction by changing the energy level parameters of the fluorescent substance. Specifically, it selects fluorescent materials whose S1 level is higher than the T1 level of the phosphorescent substance, preventing triplet excitation energy transfer to the fluorescent material. This parameter optimization eliminates the deactivation pathway while maintaining efficient phosphorescence emission.

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

This structure enables simultaneous emission of fluorescence and phosphorescence, enhancing emission efficiency and reliability of the light-emitting device.

Implementation Method 1

a first organic compound having a function of converting singlet excitation energy into light emission

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

a second organic compound having a function of converting triplet excitation energy into light emission

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 3

using protecting groups to inhibit energy transfer by the Dexter mechanism

Methodology Applied

Scientific EffectDexter mechanism:

Implementation Method 4

maintain efficient energy transfer by the Förster mechanism

Methodology Applied

Scientific EffectFörster mechanism:

Data Source

PatentUS20250326750A1Light-emitting device, light-emitting apparatus, electronic device, and lighting device

Publication Date: 2025.10.23 SEMICON ENERGY LAB CO LTD

AI summary

A light-emitting device with high emission efficiency is provided. The light-emitting device includes a fluorescent substance and a phosphorescent substance or a thermally activated delayed fluorescent material; the fluorescent substance includes a luminophore and five or more protecting groups; the luminophore is a condensed aromatic ring or a condensed heteroaromatic ring; the five or more protecting groups each have any one of an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms; the lowest singlet excitation energy level of the fluorescent substance is higher than the lowest triplet excitation energy level of the phosphorescent substance or the thermally activated delayed fluorescent material; and light emission can be obtained from both the phosphorescent substance and the phosphorescent substance or the thermally activated delayed fluorescent material.