Aromatic Derivative Electron Transport Layer for Non-Polar Light-Emitting Elements
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Solution Overview
Problem
The poor film formability of metal oxide nanoparticles on non-polar light-emitting layers in display devices, due to repulsion from polar solvents, results in coating unevenness and poor coating characteristics.
Innovation Solution
Incorporating aromatic derivatives with benzene or biphenyl skeletons containing carboxyl groups into the electron transport or hole transport layers, which are formed using a mixed solution including metal oxide nanoparticles and a polar solvent, to improve the film formability of these nanoparticles on non-polar light-emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a polar solvent is used to disperse metal oxide nanoparticles, then the nanoparticles are well dispersed, but the coating characteristics deteriorate when applied on non-polar light-emitting layers
Solution Approach 1:
The patent introduces an intermediary substance (aromatic derivative with carboxyl groups) that acts as a bridge between the polar metal oxide nanoparticles and the non-polar light-emitting layer. This intermediary contains both polar carboxyl groups that interact with metal oxide nanoparticles and non-polar aromatic hydrocarbon portions that are compatible with the non-polar underlayer, thereby enabling good coating characteristics while maintaining nanoparticle dispersion.
2Device complexity
If metal oxide nanoparticle solution is formed directly on non-polar light-emitting layer, then the structure is simplified, but film formability deteriorates due to repulsion
Solution Approach 1:
The patent changes the chemical parameter of the nanoparticle solution by adding aromatic derivatives with carboxyl groups. This modification alters the surface properties of the solution, enabling it to overcome the non-polarity of the light-emitting layer and achieve good film formability without requiring additional intermediate layers.
3Stability of the object's composition
If organic ligands are provided on quantum dot surface, then aggregation is prevented, but polarity is reduced causing water repellency
Solution Approach 1:
The patent applies local quality modification by introducing aromatic derivatives with carboxyl groups that locally interact with the quantum dot surface and metal oxide nanoparticles. These derivatives provide polar carboxyl groups at the interface while maintaining the overall non-polar character of the quantum dot ligands, thus preventing aggregation while enabling good coating characteristics.
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 approach enhances the film formability and light-emission characteristics of metal oxide nanoparticles, improving the electroluminescent emission and external quantum efficiency of the display device.
Implementation Method 1
a metal oxide nanoparticle solution constituted by a polar solvent and metal oxide nanoparticles exhibiting polarity
Implementation Method 2
a second layer provided directly on the first layer and including at least one aromatic derivative selected from an aromatic derivative having a benzene ring skeleton containing one or more carboxyl groups
Data Source
AI summary
Provided is a light-emitting element including: a first electrode; a first layer provided on the first electrode and including at least a light-emitting layer, the first layer being non-polar; an electron transport layer that is a second layer provided directly on the first layer and including at least one aromatic derivative selected from an aromatic derivative having a benzene ring skeleton containing one or more carboxyl groups and an aromatic derivative having a biphenyl skeleton containing one or more carboxyl groups, and metal oxide nanoparticles having electron transport properties; and a second electrode provided on the electron transport layer serving as the second layer.