High Refractive Index Nanocomposite Coating for OLED Light Extraction
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Solution Overview
Problem
Traditional Organic Light Emitting Diode (OLED) devices suffer from significant light loss due to the low refractive index of encapsulation materials, resulting in only about 25% of generated light being emitted, while the remaining light is lost within the device.
Innovation Solution
A high refractive index, high transparency coating formulation containing capped nanocrystals of metal oxides such as zirconium oxide, titanium oxide, or hafnium oxide, dispersed in solvents like propylene glycol monomethyl ether acetate (PGMEA), which can be easily coated onto substrates using common coating processes, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional encapsulation materials with low refractive index are used, then the device structure is simple and easy to manufacture, but light loss is significant with only 25% of generated light being emitted
Solution Approach 1:
The patent applies composite materials by combining traditional encapsulation materials with nanocrystal dispersions to create a high refractive index coating. The nanocrystals (such as TiO2, ZnO, or SiO2) are dispersed in a polymer matrix or solvent system, forming a composite encapsulation layer that achieves refractive index of 1.7 or higher while maintaining ease of application through dip-coating, spin-coating, or spray-coating processes
Solution Approach 2:
The patent changes the refractive index parameter of the encapsulation material by incorporating nanocrystals with high refractive indices (TiO2: 2.6, ZnO: 2.0, SiO2: 1.46) into the encapsulation layer. This parameter change from traditional low refractive index materials (1.4-1.6) to high refractive index composite materials (1.7 or higher) directly reduces light loss and improves light extraction efficiency
2Productivity
If high refractive index coating is applied to enhance light extraction, then light emission efficiency is dramatically improved, but the coating process complexity increases
Solution Approach 1:
The patent uses an intermediary approach by employing a solvent-based nanocrystal dispersion that can be easily applied through simple coating techniques. The dispersion medium (solvent or polymer matrix) acts as an intermediary carrier that enables uniform distribution of nanocrystals and facilitates simple application processes like dip-coating, spin-coating, or spray-coating, avoiding complex deposition equipment while achieving high refractive index coatings
Solution Approach 2:
The patent replaces complex mechanical deposition systems with simple liquid coating methods. Instead of using sophisticated physical vapor deposition or chemical vapor deposition equipment, the invention uses liquid nanocrystal dispersions that can be applied through simple dip-coating, spin-coating, or spray-coating processes, substituting complex mechanical deposition systems with straightforward liquid application methods
3Illumination intensity
If nanocrystal dispersion is used to create high refractive index coating, then optical transmittance and refractive index are optimized, but formulation stability and uniformity become challenging
Solution Approach 1:
The patent extracts the nanocrystals from complex synthesis environments and isolates them as stable dispersions in simplified solvent or polymer matrix systems. This extraction separates the nanocrystal functionality from complex synthesis conditions, creating stable, easy-to-handle formulations that maintain optical properties while improving formulation stability and ease of application
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 high refractive index coating significantly enhances the efficacy of OLED lighting and display devices by increasing the amount of emitted light, improving the performance of OLEDs and other devices like LEDs, touch screens, and solar cells.
Implementation Method 1
A high refractive index high transparency organic coating, with a refractive index around 1.8 or higher, as may be produced with a material of the present disclosure, may dramatically enhance the efficacy of the OLED lighting and display devices
Data Source
AI summary
The present disclosure provides a high refractive index acrylic formulation embedded with sub-10 nm metal oxide nanocrystals. The formulation is ideal for high refractive index, high transparency coating for a variety of optical applications including OLED lighting.