Inverted Bottom-Emitting OLED Device with Inorganic Electron Transport

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Solution Overview

Problem

Existing OLED devices require high voltage due to low electron mobility in organic materials, and the use of zinc oxide as an electron-transporting layer can damage fragile organic materials during application.

Innovation Solution

An inverted bottom-emitting OLED device structure is developed, featuring a substrate with N-type inorganic semiconductive materials as the electron-transporting layer, allowing for better compatibility with n-type semiconductors and reduced air sensitivity, with the electron-transporting layer comprising an N-type inorganic semiconductive material and an organic emitting layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If zinc oxide is used as an electron-transporting layer, then compatibility with n-type semiconductors is improved, but the fragile organic materials can be damaged during application

Engineering Contradiction:

Improvecompatibility with n-type semiconductorsVSAvoiddamage to organic materials

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The device is divided into two separate sections: an inorganic electron-transporting layer (ZnO) for electron transport and injection, and an organic light-emitting layer for light emission. This segmentation allows each material to perform its optimal function without the ZnO directly contacting and damaging the organic materials during application.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inorganic electron-transporting layer acts as an intermediary between the n-type semiconductor (ZnO) and the organic light-emitting layer. It provides the necessary electron transport capability while preventing direct contact between the ZnO application process and the fragile organic materials, thus protecting them from damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If organic materials are used for electron transport, then device structure is simplified, but high voltage is required due to low electron mobility

Engineering Contradiction:

Improvedevice structureVSAvoidvoltage requirement

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The device uses a composite structure combining inorganic ZnO material for electron transport with organic materials for light emission. The inorganic ZnO layer provides superior electron mobility compared to purely organic electron-transporting materials, thereby reducing the voltage requirement while maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If organic electron-transporting layer is used, then manufacturing flexibility is improved, but air sensitivity increases requiring stringent moisture protection

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidair sensitivity

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The device separates the electron-transporting function (handled by inorganic ZnO) from the light-emitting function (handled by organic materials). The inorganic ZnO layer is deposited first in a controlled environment, and subsequent organic layers are applied without requiring the ZnO to be air-sensitive, thereby reducing the overall air sensitivity constraints during manufacturing.

Inventive Principle:

Principle #1Segmentation

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 configuration reduces the need for high voltage and enhances compatibility with n-type semiconductors, improving the stability and manufacturing flexibility of OLED devices by allowing pre-manufacturing of substrates with active matrix electronics without requiring stringent moisture protection.

Implementation Method 1

providing an electron-transporting layer over the substrate and first electrode(s), wherein the electron-transporting layer comprises an N-type inorganic semiconductive material

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Implementation Method 2

The organic electroluminescent media supports recombination of holes and electrons that yield emissions of light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8102114B2Method of manufacturing an inverted bottom-emitting OLED device

Publication Date: 2012.01.24 GLOBAL OLED TECHNOLOGY LLC

AI summary

A method of making an inverted bottom-emitting OLED device, comprising: providing a substrate; providing one or more first electrodes driven by n-type transistors on the substrate; providing an electron-transporting layer over the substrate and first electrode(s), wherein the electron-transporting layer comprises an n-type inorganic semiconductive material with a resistivity in the range of 1 to 105 ohm-cm and a bandgap greater than 2.5 eV; providing an organic light-emitting layer over the electron-transporting layer; providing a hole-transporting layer over the organic emitting layer; and providing a second electrode over the hole-transporting layer.