New permeation rate measurement for thin film encapsulation of organic light emitting diodes

We have developed a new method to measure the water vapor transmission ratio (WVTR) for thin film encapsulation (TFE) of organic light emitting diodes (OLEDs). It is a nondestructive method to measure WVTR by investigating the change of photoluminescent spectra of organic material. This method can be realized easily by online test. By calibrating the evolution curve (the photoluminescent intensity versus time), we have figured out the relative water transmission which was responded by organic materials. The WVTR of TFE devices is estimated to be about 2.0 × 10^-2 gm^-2 day^-1 in a controlled environment of 85% relative humidity (RH) at 38°C. Novel thin film encapsulation devices have also been presented.