Organic Electroluminescent Device with Segmented P-Type Doped Layers

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Solution Overview

Problem

Existing organic electroluminescent devices face challenges in achieving carrier balance between holes and electrons, leading to inefficiencies and reduced device lifetime due to the higher mobility of holes compared to electrons, which results in carrier imbalance and heat accumulation at interfaces.

Innovation Solution

The introduction of a novel organic electroluminescent device structure featuring multiple p-type doped organic layers, where a first organic layer with a first p-type dopant and a second organic layer with a second p-type dopant are in contact, allowing for controlled hole injection and balancing electron and hole concentrations, improving device performance and lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If hole transporting materials with strong electron donation abilities are used to achieve good hole conduction, then hole mobility is improved, but carrier concentration imbalance occurs with holes much greater than electrons

Engineering Contradiction:

Improvehole mobilityVSAvoidcarrier concentration balance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The hole transporting layer is segmented into multiple sub-layers with different p-type dopants (first p-type dopant in first organic layer, second p-type dopant in second organic layer). This segmentation allows independent optimization of hole mobility and carrier balance in different regions, resolving the contradiction between high hole mobility and carrier concentration balance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different p-type dopants are used in different local regions (first organic layer and second organic layer) to create local variations in hole transporting capability. The first p-type dopant optimizes for hole mobility while the second p-type dopant optimizes for carrier balance, allowing each region to have the quality needed for its specific function.

Inventive Principle:

Principle #3Local quality

2Reliability

If the thickness of the hole transporting layer is increased to balance carrier concentrations, then carrier balance is improved, but device voltage increases and efficiency decreases

Engineering Contradiction:

Improvecarrier concentration balanceVSAvoiddevice voltage and efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of changing the thickness parameter of the hole transporting layer, the invention changes the chemical composition parameter by introducing different p-type dopants in different layers. This allows carrier balance to be achieved through chemical optimization rather than physical thickening, maintaining low voltage and high efficiency while achieving carrier balance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If carrier balance is achieved by improving electron injection and transporting performance, then carrier concentration balance is improved, but the number of selectable organic materials is limited

Engineering Contradiction:

Improvecarrier concentration balanceVSAvoidmaterial selection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of improving electron injection and transporting performance to achieve carrier balance, the invention inverts the approach by using p-type dopants in the hole transporting layer to regulate hole concentration. This inversion expands material selection flexibility since p-type dopants can be combined with various host materials without limiting electron transporting material choices.

Inventive Principle:

Principle #13The other way round (Inversion)

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 multi-layer structure significantly enhances the overall performance and extends the lifetime of the device by effectively balancing carrier concentrations and reducing heat accumulation, resulting in improved light emission efficiency and stability.

Implementation Method 1

the first organic layer comprises a first organic material and a first p-type dopant; the second organic layer comprises a second organic material and a second p-type dopant

Methodology Applied

Scientific EffectCharge carrier transport: Conduction (electrical)

Implementation Method 2

converts electrical energy into light through a voltage applied at both the cathode and the anode of the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20230422609A1Organic electroluminescent device

Publication Date: 2023.12.28 BEIJING SUMMER SPROUT TECH CO LTD

AI summary

Provided is an organic electroluminescent device. The organic electroluminescent device comprises an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a first organic layer and a second organic layer; the first organic layer comprises a first organic material and a first p-type dopant; the second organic layer comprises a second organic material and a second p-type dopant; the first organic layer is in contact with the second organic layer, and the second organic layer is above the first organic layer; and the p-type dopant has a structure represented by Formula 1. The organic electroluminescent device comprising the p-type dopant of a particular structure and having a particular device structure can significantly improve the overall performance of the device and especially improve the lifetime of the device. Further provided is an electronic assembly comprising the organic electroluminescent device.