OLED Electron Density Control Layer for High Efficiency

Solution Overview

Problem

Existing organic light-emitting diodes face limitations in achieving high luminous efficiency and effective low-voltage operation due to inefficiencies in electron density control and exciton generation.

Innovation Solution

Incorporating a specifically structured electron density control layer with compounds represented by Chemical Formulas A to D, in combination with an anthracene derivative in the light-emitting layer, to enhance electron injection and exciton density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional electron transport layer is used directly on the light-emitting layer, then the device structure is simple, but electron density control is insufficient and luminous efficiency is low

Engineering Contradiction:

Improvedevice structureVSAvoidluminous efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The electron transport function is segmented into two distinct layers: an electron transport layer in direct contact with the light-emitting layer, and an electron density control layer positioned between the electron transport layer and the cathode. This segmentation allows each layer to perform its specific function optimally, with the electron density control layer specifically responsible for regulating electron density to enhance luminous efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electron density control layer acts as an intermediary between the electron transport layer and the cathode. It mediates electron flow by controlling electron density in the light-emitting layer, thereby improving exciton generation and luminous efficiency without disrupting the overall device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If electron density is increased to improve exciton generation, then luminous efficiency improves, but device complexity increases

Engineering Contradiction:

Improveluminous efficiencyVSAvoiddevice structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The electron transport function is segmented into two distinct layers: an electron transport layer in direct contact with the light-emitting layer, and an electron density control layer positioned between the electron transport layer and the cathode. This segmentation allows each layer to perform its specific function optimally, with the electron density control layer specifically responsible for regulating electron density to enhance luminous efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electron density control layer performs multiple functions simultaneously: it controls electron density, regulates electron flow, and enhances exciton generation. This multi-functionality allows the device to achieve high luminous efficiency without proportionally increasing complexity, as one layer accomplishes multiple objectives.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Quantity of substance

If high voltage is applied to achieve sufficient electron injection, then electron density is adequate, but power consumption increases

Engineering Contradiction:

Improveelectron densityVSAvoidpower consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The electron density control layer acts as an intermediary between the electron transport layer and the cathode. It mediates electron flow by controlling electron density in the light-emitting layer, thereby improving exciton generation and luminous efficiency without requiring high operating voltages.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electron density control layer changes the electrical parameters (electron density, electron mobility) in the light-emitting layer to optimal values. This allows the device to operate at lower voltages while maintaining adequate electron density for efficient exciton generation and light emission.

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If triplet excitons are allowed to escape the light-emitting layer, then device complexity is reduced, but luminous efficiency decreases due to loss of triplet-triplet fusion

Engineering Contradiction:

Improveenergy management structureVSAvoidluminous efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The electron density control layer is designed with specific local properties: it has a triplet energy level higher than the host material in the light-emitting layer. This local quality difference creates an energy barrier that confines triplet excitons within the light-emitting layer, enabling triplet-triplet fusion to occur and generate singlet excitons for light emission.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electron density control layer converts the potentially harmful loss of triplet excitons into a beneficial effect. By confining triplet excitons through its higher triplet energy level, it enables triplet-triplet fusion to occur, transforming non-emissive triplet states into emissive singlet states that contribute to light emission and improve luminous efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 organic light-emitting diodes exhibit improved luminous efficiency and effective low-voltage operation by increasing electron density and exciton generation, surpassing conventional diodes in current efficiency and external quantum efficiency.

Implementation Method 1

the anode injects holes which are then transferred to the light-emitting layer via the hole transport layer while electrons injected from the cathode move to the light-emitting layer via the electron transport layer

Methodology Applied

Scientific EffectElectron injection:

Implementation Method 2

In the luminescent zone, the carriers such as holes and electrons recombine to produce an exciton. When the exciton returns to the ground state from the excited state, the molecule of the light-emitting layer emits light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

when a dopant which is smaller in energy band gap than a host forming a light-emitting layer is added in a small amount to the light-emitting layer, excitons are generated from the light-emitting layer and transported to the dopant, emitting light at high efficiency

Methodology Applied

Scientific EffectEnergy transfer:

Data Source

PatentUS10559758B2Organic light emitting diode of high efficiency

Publication Date: 2020.02.11 SFC CO LTD

AI summary

Disclosed herein is an organic light-emitting diode, comprising: a first electrode; a second electrode facing the first electrode; and a light-emitting layer and an electron density control layer in that order between the first electrode and the second electrode, wherein the electron density control layer includes at least one selected from among compounds represented by the following Chemical Formulas A to D, and the light emitting layer includes at least one anthracene compound represented by the following Chemical Formula H. The structures of Chemical Formulas A to D and H are as described in the specification.