OLED Electron-Transport Layer for Low-Index Light Outcoupling

Solution Overview

Problem

Organic light-emitting devices (OLEDs) face challenges with low outcoupling efficiency due to refractive index differences between layers, which affects carrier-transport properties and reliability, and existing solutions struggle to balance refractive index with carrier-transport performance.

Innovation Solution

A light-emitting apparatus with a refractive index of 1.75 or lower for 467-nm wavelength light, incorporating a monoamine compound with aromatic rings and a specific carbon bond structure, or a mixed material of organic and inorganic compounds, including a fluoride of alkali or alkaline earth metals, in the electron-transport layer, combined with a color conversion layer using quantum dots for enhanced emission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a low refractive index material is introduced in the EL layer to reduce reflection loss, then outcoupling efficiency is improved, but carrier-transport property deteriorates

Engineering Contradiction:

Improveoutcoupling efficiencyVSAvoidcarrier-transport property

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by introducing a low refractive index material specifically in the electron-transport layer adjacent to the light-emitting layer, while maintaining other layers with conventional materials. This localized modification reduces reflection loss at the critical interface without compromising the overall carrier-transport properties of the device.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining a low refractive index material (such as a fluoride compound) with an electron-transport material in the electron-transport layer. This composite structure achieves both low refractive index for improved outcoupling efficiency and sufficient electron-transport capability for maintaining device reliability.

Inventive Principle:

Principle #40Composite materials

2Productivity

If a low refractive index material is introduced in the EL layer to reduce reflection loss, then external quantum efficiency is improved, but device reliability deteriorates

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoiddevice reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by introducing a low refractive index material specifically in the electron-transport layer adjacent to the light-emitting layer, while maintaining other layers with conventional materials. This localized modification reduces reflection loss at the critical interface without compromising the overall carrier-transport properties of the device.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining a low refractive index material (such as a fluoride compound) with an electron-transport material in the electron-transport layer. This composite structure achieves both low refractive index for improved outcoupling efficiency and sufficient electron-transport capability for maintaining device reliability.

Inventive Principle:

Principle #40Composite materials

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 improves outcoupling efficiency, external quantum efficiency, and reduces driving voltage while maintaining high reliability and low power consumption, achieving high emission efficiency and long device lifetime.

Implementation Method 1

it is not easy to form such a layer with a low refractive index in an EL layer without adversely affecting other critical characteristics of the light-emitting device

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

A color conversion method is a method in which a photoluminescent substance is irradiated with light from light-emitting devices to convert the light into light of desired colors

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 3

The first color conversion layer includes a first substance that absorbs light and emits light

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 4

The first color conversion layer includes a first substance that absorbs light and emits light

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS11800734B2Light-emitting device, electronic device, and lighting device

Publication Date: 2023.10.24 SEMICON ENERGY LAB CO LTD

AI summary

A light-emitting apparatus with low power consumption is provided. A light-emitting apparatus including a first light-emitting device and a first color conversion layer. The first light-emitting device includes an anode, a cathode, and an EL layer positioned between the anode and the cathode. The EL layer includes a layer including a material with a refractive index lower than or equal to 1.75 at 467 nm. The first color conversion layer includes a first substance capable of emission by absorbing light. Light emitted from the first light-emitting device enters the first color conversion layer.