Sheet-like sealing material for organic EL devices
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Solution Overview
Problem
Organic EL devices face deterioration in emission properties due to water, oxygen, and ultraviolet exposure, leading to issues with luminance, luminous efficiency, and luminous uniformity, and existing sealing materials may yellow or lose transparency when increased UV absorbers are used to enhance light resistance.
Innovation Solution
A sheet-like sealing material with a low water vapor transmission rate, specific colorimetric properties, and high light transmittance at 420 nm, composed of rubber-based or polyolefin-based polymers with a UV absorber, providing excellent water barrier, light resistance, and transparency while maintaining adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of UV absorber is increased to improve light resistance, then the light resistance is improved, but the resin layer yellows and transparency deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the UV absorber by selecting specific compounds (benzotriazole and phenyl salicylate) with defined molecular structures and absorption characteristics. This allows achieving adequate UV protection while controlling the concentration and type of absorber to minimize yellowing and maintain transparency.
Solution Approach 2:
The patent uses a composite resin system combining multiple polymer components (polyester resin, acrylic resin, and silane-modified polyester resin) with UV absorbers. This composite approach distributes the UV absorption function across different materials, reducing the burden on any single UV absorber compound and thereby minimizing yellowing while maintaining overall light resistance and transparency.
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 sheet-like sealing material effectively prevents water and UV-induced deterioration, maintaining the organic EL device's emission properties and transparency without yellowing, ensuring reliable performance and durability.
Implementation Method 1
the sheet-like sealing material has low light transmittance at a wavelength of 370 nm, indicating effective UV absorption to protect the organic EL device
Implementation Method 2
the sheet-like sealing material has a water vapor transmission rate at a temperature of 40°C and a relative humidity of 90% of 20 g/(m²·24 h) or less, providing effective water barrier capability
Data Source
AI summary
The present invention is a sheet-like sealing material comprising one sealing resin layer, or two or more sealing resin layers, the sheet-like sealing material having a water vapor transmission rate at a temperature of 40°C and a relative humidity of 90% of 20 g/(m2·day) or less when the sheet-like sealing material has a thickness of 50 µm, having a b* value in a CIE L*a*b* color system defined by JIS Z 8729-1994 of -2 to 2%, having a light transmittance at a wavelength of 370 nm of 1% or less, and having a light transmittance at a wavelength of 420 nm of 85% or more; and a sealing sheet comprising the sheet-like sealing material that comprises one sealing resin layer, or two or more sealing resin layers, and a gas barrier layer; and an electronic device that is sealed with the sheet-like sealing material or the sealing sheet.