Osmium(IV) Complexes for Blue OLED Emission

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Solution Overview

Problem

Osmium(II) complexes have shallow HOMO levels, making it difficult to tune emission energy to the blue region due to small band gaps, and are prone to exciplex formation, limiting their application in organic light-emitting diodes (OLEDs).

Innovation Solution

Osmium(IV) complexes with deeper HOMO levels and higher oxidation states are used, allowing for better alignment of emission energy and reduced exciplex formation, enabling more efficient blue emission and improved color tuning in OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If Osmium(II) complexes are used, then the device structure is simpler, but the emission energy cannot be tuned to blue region and exciplex formation occurs

Engineering Contradiction:

Improvedevice structureVSAvoidemission energy tuning

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent changes the oxidation state parameter of the osmium complex from +2 to +4, which fundamentally alters the HOMO level depth and band gap characteristics. This parameter change enables blue region emission by creating sufficient energy difference between HOMO and LUMO levels, while also reducing exciplex formation tendency through the deeper HOMO level positioning.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If Osmium(II) complexes are used, then the synthesis process is easier, but blue emission is difficult to achieve

Engineering Contradiction:

Improvesynthesis processVSAvoidblue emission

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

By changing the oxidation state from +2 to +4, the patent achieves deeper HOMO levels and larger band gaps, which are essential for blue emission. The synthesis process maintains feasibility through established coordination chemistry methods for forming osmium(IV) complexes with appropriate ligands, balancing manufacturing ease with optical performance.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If Osmium(II) complexes are used, then the material cost is lower, but exciplex formation limits application

Engineering Contradiction:

Improvematerial costVSAvoidexciplex formation immunity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The oxidation state change from +2 to +4 creates deeper HOMO levels that are better aligned with common OLED host materials, reducing the energy mismatch that causes exciplex formation. This parameter change improves device reliability and performance consistency while maintaining cost-effectiveness through the use of standard coordination chemistry synthesis procedures.

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

Osmium(IV) complexes facilitate easier achievement of blue emission and increased immunity to exciplex formation, offering greater flexibility and performance in OLEDs compared to Os(II) complexes.

Implementation Method 1

One application for phosphorescent emissive molecules is a full color display

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS11145831B2Osmium(IV) complexes for OLED materials

Publication Date: 2021.10.12 UNIVERSAL DISPLAY CORP

AI summary

A novel compound having the formula Os(L)n is disclosed, wherein Os is osmium(IV) metal, L is a ligand coordinating to the Os atom, and n is an integer from 1 to 6, wherein each L can be same or different, wherein at least one L is a multidentate ligand, and wherein the compound is neutral.