OLED Multi-Layer Electron Transport Structure

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Solution Overview

Problem

Conventional organic light-emitting devices face limitations in achieving high light-emitting efficiency and long lifetime due to the challenges of combining multiple organic material layers for optimized charge balance and reduced driving voltage.

Innovation Solution

An organic light-emitting device with a multi-layer electron transport layer structure, comprising at least one first layer and two second layers with lower electron mobility, alternately stacked, and optionally including hole and electron implant layers, to adjust charge balance and mobility, thereby reducing driving voltage and enhancing light-emitting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple organic material layers are combined to optimize charge balance and reduce driving voltage, then light-emitting efficiency and lifetime are improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvelight-emitting efficiencyVSAvoidelectron transport layer structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The electron transport layer is segmented into multiple sub-layers with different electron mobility characteristics. This includes a first electron transport layer with higher electron mobility and a second electron transport layer with lower electron mobility, allowing independent optimization of charge transport in different regions of the device

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electron transport layer are assigned different material properties and electron mobility values to match local requirements. The first electron transport layer uses materials with higher electron mobility near the cathode, while the second layer uses materials with lower electron mobility closer to the light-emitting layer, creating locally optimized charge transport

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If multiple organic material layers are combined to optimize charge balance, then lifetime is extended, but ease of manufacture decreases

Engineering Contradiction:

Improvedevice lifetimeVSAvoidlayer combination process

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The patent systematically varies key parameters including electron mobility values, layer thicknesses, and material selection across different electron transport layers. By establishing parameter ranges and optimization criteria, the complex multi-layer structure becomes more manageable in terms of manufacturing and quality control

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If driving voltage is reduced through optimized layer structure, then energy consumption decreases, but achieving optimal charge balance becomes more difficult

Engineering Contradiction:

Improvedriving voltageVSAvoidcharge balance optimization

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The electron transport layer structure is designed to dynamically adapt to different operating conditions through the use of materials and configurations that optimize electron transport at different voltage levels, allowing the device to maintain efficient charge balance across varying driving voltages

Inventive Principle:

Principle #15Dynamics

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 multi-layer structure effectively adjusts charge balance, resulting in improved light-emitting efficiency and extended lifetime by reducing brightness decrease and lowering driving voltage, outperforming conventional devices in both aspects.

Implementation Method 1

an electron transport layer arranged between the organic light-emitting layer and the second electrode, wherein the electron transport layer includes a multi-layer structure that includes at least one first layer and at least two second layers, wherein ones of said at least one first layer and ones of said at least two second layers are alternately stacked

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Implementation Method 2

A voltage difference is applied across the organic light-emitting layer via the anode or cathode causing the organic light-emitting layer to emit visible light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8415687B2Organic light-emitting device

Publication Date: 2013.04.09 SAMSUNG DISPLAY CO LTD

AI summary

An organic light emitting device with improved light emitting efficiency, the organic light emitting device includes a substrate, a first electrode arranged on the substrate, a second electrode arranged to face the first electrode, an organic light-emitting layer arranged between the first electrode and the second electrode, an electron transport layer arranged between the organic light-emitting layer and the second electrode, wherein the electron transport layer includes a multi-layer structure that includes at least one first layer and at least two second layers, wherein ones of said at least one first layer and ones of said at least two second layers are alternately stacked, wherein ones of the at least two second layers are arranged at both opposite ends of the electron transport layer, each of the at least two second layers having a lower electron mobility than that of each of the at least one first layer.