OLED Light-Emitting Layer with Three Successive Sub-Layers

Solution Overview

Problem

Existing OLEDs face inefficiencies due to non-radiative transitions of excitons diffusing to undoped regions, leading to energy loss and reduced carrier utilization ratios, which affects light-emitting efficiency.

Innovation Solution

The implementation of a light-emitting layer comprising three successive sub-layers, each doped with a matrix material of varying hole and electron transport capacities, with specific energy level alignments to optimize carrier recombination and reduce energy loss, including a first sub-layer close to the anode, a second sub-layer with a mixture of hole and electron transport materials, and a third sub-layer near the cathode, all doped with phosphorescent materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light-emitting layer is used, then the device structure is simple, but carrier utilization ratio is low due to exciton diffusion to undoped regions causing non-radiative transitions

Engineering Contradiction:

Improvelight-emitting layer structureVSAvoidenergy loss from non-radiative transitions

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The light-emitting layer is divided into three successive sub-layers (first, second, and third light-emitting sub-layers), each with distinct matrix materials optimized for different carrier transport functions. This segmentation creates localized recombination regions that confine excitons within doped regions, preventing diffusion to undoped areas and eliminating non-radiative transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each light-emitting sub-layer is assigned specific matrix materials with tailored properties: the first sub-layer uses a matrix material with high electron mobility, the second uses a mixture of hole and electron transport materials, and the third uses a matrix material with high hole mobility. This local quality optimization ensures that recombination occurs in appropriate regions with suitable carrier transport characteristics, maximizing radiative efficiency.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a single light-emitting layer is used, then the manufacturing process is simple, but light-emitting efficiency is reduced due to poor carrier recombination

Engineering Contradiction:

Improvepreparation processVSAvoidlight-emitting efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The light-emitting layer is segmented into three sub-layers with distinct matrix materials optimized for different carrier transport functions. This segmentation creates localized recombination regions that confine excitons within doped regions, preventing diffusion to undoped areas and eliminating non-radiative transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The matrix materials in each sub-layer are selected with specific mobility parameters: the first sub-layer uses a matrix material with high electron mobility, the second uses a mixture of hole and electron transport materials, and the third uses a matrix material with high hole mobility. This parameter optimization ensures efficient carrier recombination and high radiative efficiency.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If matrix materials with different transport capacities are used in successive sub-layers, then carrier utilization ratio is improved, but device structure becomes more complex

Engineering Contradiction:

Improvecarrier utilization ratioVSAvoidorganic functional layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The light-emitting layer is divided into three successive sub-layers (first, second, and third light-emitting sub-layers), each with distinct matrix materials optimized for different carrier transport functions. This segmentation creates localized recombination regions that confine excitons within doped regions, preventing diffusion to undoped areas and eliminating non-radiative transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each light-emitting sub-layer is assigned specific matrix materials with tailored properties: the first sub-layer uses a matrix material with high electron mobility, the second uses a mixture of hole and electron transport materials, and the third uses a matrix material with high hole mobility. This local quality optimization ensures that recombination occurs in appropriate regions with suitable carrier transport characteristics, maximizing radiative efficiency.

Inventive Principle:

Principle #3Local quality

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 enhances carrier utilization and light-emitting efficiency by creating wider recombination regions and reducing non-radiative transitions, resulting in improved current efficiency and luminosity performance compared to traditional OLED structures.

Implementation Method 1

the holes and the electrons entering the light emitting layer 6 recombine with each other in the recombination region to form excitons, which undergo radiative transition to emit light, that is, resulting in electroluminescence

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

each doped with phosphorescent materials

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS9166184B2Organic light emitting device having three successive light emitting sub-layers with mixture matrix material for the second light emitting sub-layer and method of preparing same and display device thereof

Publication Date: 2015.10.20 BOE TECHNOLOGY GROUP CO LTD

AI summary

Disclosed is an organic light-emitting device comprising a substrate (1), an anode layer (2), a cathode layer (10) and an organic functional layer comprising a light-emitting layer (6); the light-emitting layer (6) comprises three successive light-emitting sub-layers, i.e., a first light-emitting sub-layer (61) close to the anode layer, a second light-emitting sub-layer (62), and a third light-emitting sub-layer (63) close to the cathode layer. This organic light-emitting device can effectively improve the carrier utilization ratio and thereby improving the light-emitting efficiency of the organic light-emitting device.