OLED Emission Layer Index Layout for Lower Waveguide Loss

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Solution Overview

Problem

Current light-emitting devices face challenges in achieving high luminescence efficiency and long lifespan due to light loss through waveguide modes and heat accumulation, which affects their performance and stability.

Innovation Solution

A light-emitting device design incorporating a hole transport region with an electron blocking layer, a first emission layer with a higher refractive index than the electron blocking layer, and a second emission layer with a refractive index equal to or greater than the hole blocking layer, reducing light loss and heat accumulation by optimizing refractive indices and layer configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional emission layers with standard refractive indices are used, then device structure is simple, but light loss through waveguide modes increases and luminescence efficiency decreases

Engineering Contradiction:

Improvelight loss through waveguide modesVSAvoidlayer configuration complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by optimizing the refractive indices of emission layers and blocking layers. Specifically, the first emission layer has a refractive index higher than the electron blocking layer, and the second emission layer has a refractive index equal to or higher than the hole blocking layer. This parameter optimization reduces light loss through waveguide modes and improves luminescence efficiency without significantly complicating the device structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by creating specific refractive index relationships in different regions of the device. The electron blocking layer and hole blocking layer are designed with refractive indices lower than their adjacent emission layers, creating localized optical properties that prevent waveguide mode formation at critical interfaces where light extraction is most problematic.

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If conventional blocking layers with standard refractive indices are used, then manufacturing is easier, but heat accumulation increases and device lifespan decreases

Engineering Contradiction:

Improvedevice lifespanVSAvoidmaterial selection constraints

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The patent changes the refractive index parameter of blocking layers to be lower than adjacent emission layers. This parameter modification improves heat management by reducing heat accumulation at layer interfaces, thereby extending device lifespan. The specific requirement that electron blocking layer refractive index is lower than the first emission layer and hole blocking layer refractive index is lower than the second emission layer provides clear material selection criteria.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If emission layers with optimized refractive indices are used, then luminescence efficiency is enhanced, but material selection becomes more restrictive

Engineering Contradiction:

Improveluminescence efficiencyVSAvoidmaterial selection flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent optimizes luminescence efficiency by establishing specific refractive index relationships: the first emission layer has a higher refractive index than the electron blocking layer, and the second emission layer has a refractive index equal to or higher than the hole blocking layer. This parameter optimization enhances light extraction efficiency while providing clear material selection guidelines that balance performance requirements with material availability.

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 optimized refractive index configuration reduces light loss through waveguide modes, enhancing luminescence efficiency and extending the device's lifespan, making it suitable for high-quality electronic applications.

Implementation Method 1

a refractive index of the first emission layer may be greater than a refractive index of the electron blocking layer, a refractive index of the second emission layer may be equal to or greater than a refractive index of the hole blocking layer

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20230301134A1Light-emitting device and electronic apparatus including the same

Publication Date: 2023.09.21 SAMSUNG DISPLAY CO LTD

AI summary

A light-emitting device includes a first electrode; a second electrode facing the first electrode; and an interlayer between the first electrode and the second electrode. The interlayer includes a hole transport region including an electron blocking layer, a first emission layer between the electron blocking layer and the second electrode, a second emission layer between the first emission layer and the second electrode, and an electron transport region between the second emission layer and the second electrode and including a hole blocking layer.