BiL3 Host Materials for OLED Emission Efficiency

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Solution Overview

Problem

Current organic light-emitting diode (OLED) technologies face challenges in achieving saturated colors and efficient light emission, particularly in producing red, green, and blue pixels, which are essential for full-color displays, and in optimizing the performance of emissive layers using conventional materials.

Innovation Solution

A compound with a stoichiometry formula of BiL3, where Bi is Bi (III) and L is a mono-anionic bidentate ligand, is used in an OLED's organic layer to enhance the HOMO and LUMO levels, allowing for the tuning of charge carrier density and conductivity, thereby improving the emission efficiency and color saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional OLED materials are used, then device structure and materials are simpler and cheaper, but emission efficiency and color saturation are insufficient

Engineering Contradiction:

Improvesimplicity of device structure and materialsVSAvoidemission efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent employs composite material strategy by combining Bi(III) compounds with specific organic ligands (containing N, O, or S donors) to create hybrid emissive materials. This composite approach enables simultaneous achievement of high emission efficiency through photoluminescence properties and color saturation through tunable HOMO/LUMO levels, while maintaining compatibility with conventional OLED device structures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies parameter changes by systematically varying ligand structures (different donors, substituents, and configurations) to tune the electronic properties of Bi(III) compounds. By adjusting HOMO and LUMO energy levels through ligand modification, the patent optimizes charge carrier density and conductivity parameters to achieve enhanced emission efficiency and color saturation without fundamentally changing device architecture.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional OLED materials are used, then manufacturing cost is lower, but color saturation for full-color displays is insufficient

Engineering Contradiction:

Improvemanufacturing costVSAvoidcolor saturation

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent utilizes parameter changes by modifying ligand structures to precisely control HOMO and LUMO energy levels of Bi(III) compounds. This enables tuning of optical properties to achieve saturated red, green, and blue emissions required for full-color displays, while maintaining cost-effectiveness through solution processing and conventional fabrication methods.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality principle by designing specific ligand environments around Bi(III) centers to achieve distinct color emissions. Different ligand configurations (varying donors, substituents at specific positions) create localized electronic structures that emit specific saturated colors, allowing precise color control in different device regions for full-color display applications.

Inventive Principle:

Principle #3Local quality

3Reliability

If BiL3 compounds are used to enhance HOMO and LUMO levels, then charge carrier density and conductivity improve, but material complexity increases

Engineering Contradiction:

Improvecharge carrier density and conductivityVSAvoidmaterial complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs parameter changes by systematically adjusting ligand structures (donor types, substituents, configurations) to optimize HOMO and LUMO energy levels of Bi(III) compounds. This enables precise control of charge carrier density and conductivity parameters while managing material complexity through rational molecular design and selection of commercially available ligand building blocks.

Inventive Principle:

Principle #35Parameter changes

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 use of BiL3 compounds in OLEDs enables the production of OLEDs with improved charge carrier density and conductivity, leading to enhanced emission efficiency and color saturation, effectively addressing the limitations of conventional OLED materials in achieving saturated colors.

Implementation Method 1

Methodology Applied

Scientific EffectElectron coordination:

Implementation Method 2

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11716900B2Host materials for electroluminescent devices

Publication Date: 2023.08.01 UNIVERSAL DISPLAY CORP

AI summary

A compound having a stoichiometry formula of BiL3, where each L has a formula ofwhere each Z1 and Z2 is O, S, NR, or PR; Z3 is C; Z1, Z2, the single dashed line represent a bond to Bi; and n is an integer. In these structures, LA can be aryl or heteroaryl, which can be substituted. Substituents RL, R, LC, and RLC can be selected from a variety of substituents. In the first formula, at least one of the following is true: (1) LA includes a 5-membered ring; (2) LA includes a condensed ring system of at least three rings; (3) at least one RL is a non-fused aryl or heteroaryl moiety; or (4) n is at least 2 with two different RL's and LA-(RL)n is asymmetrical. Organic light emitting devices, consumer products, formulations, and chemical structures containing the compounds are also disclosed.