Light Scattering Layer Voids Organic Electroluminescent Device
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in extracting light due to total reflection of light at critical angles, and the dispersion of metal oxide particles in light scattering layers is difficult, leading to poor adhesion and low concentration issues.
Innovation Solution
A method of preparing a light scattering layer using voids instead of metal oxide particles, where an emulsion is formed by dispersing droplets of a second phase into a hydrophobic metal oxide sol, and then converted into a metal oxide matrix layer with voids through baking and calcining, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If metal oxide particles are dispersed into a matrix of a light scattering layer, then the refractive index of the light scattering layer may be changed and light may be scattered at boundaries, but it is difficult to disperse metal oxide particles into the matrix at high concentration due to poor adhesion
Solution Approach 1:
The patent uses a silane coupling agent as an intermediary substance between the metal oxide particles and the polymer matrix. This coupling agent contains both inorganic bonding groups (that bond to metal oxide surfaces) and organic bonding groups (that bond to the polymer matrix), thereby improving adhesion and enabling high-concentration dispersion of metal oxide particles in the light scattering layer
Solution Approach 2:
The patent modifies the surface properties of metal oxide particles by treating them with silane coupling agents, changing their surface chemistry from hydrophilic to hydrophobic characteristics. This parameter change in surface properties improves compatibility with the polymer matrix and enables better dispersion at high concentrations
2Illumination intensity
If metal oxide particles are dispersed into a matrix of a light scattering layer, then light scattering may be improved, but the adhesion between metal oxide particles and the matrix is poor
Solution Approach 1:
The silane coupling agent serves as a molecular bridge between metal oxide particles and the polymer matrix. The coupling agent forms strong chemical bonds with both the inorganic metal oxide surface and the organic polymer chains, significantly improving interfacial adhesion strength while maintaining light scattering performance
Solution Approach 2:
The patent creates a composite material system consisting of metal oxide particles, silane coupling agent, and polymer matrix. This composite structure combines the light scattering properties of metal oxide with the mechanical properties of the polymer, while the coupling agent ensures strong interfacial bonding between the components
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 voids in the light scattering layer significantly improves light extraction efficiency, achieving up to 3.8 times more light extraction compared to devices without such layers, while maintaining mechanical strength and surface roughness.
Implementation Method 1
obtaining an emulsion by dispersing droplets of a second phase into a first phase including a hydrophobic metal oxide sol
Implementation Method 2
converting the emulsion layer into a matrix precursor layer by baking the emulsion layer and thus solidifying the first phase
Implementation Method 3
converting the matrix precursor layer into a metal oxide matrix layer by calcining the matrix precursor layer
Implementation Method 4
Light scattering layers including light scattering particles have been introduced to improve light-extracting efficiency
Data Source
AI summary
Provided is a method of preparing a light scattering layer including voids as a light scattering enhancer instead of metal oxide particles. Provided is also a light scattering layer including voids as a light scattering enhancer instead of metal oxide particles. Provided is also an organic electroluminescent device including the light scattering layer that includes voids as the light scattering enhancer instead of metal oxide particles.