Ultralow Water Vapor Permeation Measurement Using Tritium for OLED Displays

Flexible organic light-emitting devices (OLEDs) are considered to be a next-generation display technology. However, since the materials currently used in OLEDs are highly sensitive to water vapor, a low-water-vapor permeation measurement technology is essential to the development of flexible barrier substrates for encapsulation of OLEDs. This study developed a testing device for water vapor permeation in the range of (10(-3) similar to 10(-6)) g.m(-2)day(-1), which is necessary for the display industry, by using water that included tritium, a radioactive isotope. This method enabled an absolute quantitative measurement of water vapor permeation. The uncertainty of the established apparatus was about 1.88 x 10(-6) g.m-(2)day(-1) with respect to a specimen having a water vapor permeation of 10(-5) g.m(-2)day(-1), but it is expected that this testing range could be expanded if the temperature of the test chamber were to be increased.