The flexible ceramic substrate is said to be much easier to handle than metal foils or flexible glass, and it has both intrinsic moisture barrier properties and high-temperature capabilities up to 1000ºC. These material properties help simplify the fabrication of OLED flexible devices, since only a top moisture barrier is required to protect the OLED layers deposited onto the ceramic substrate, compared to plastic-based OLEDs that require protection barriers on both sides of the layers.
Tests on a 120x25mm OLED prototype have shown that the Thin E-Strate-based OLED had a water vapour transmission rate (WVTR) below 8.5x10 -7 g/m 2/day with only a thin film top encapsulation directly deposited by the Holst Centre through plasma enhanced chemical vapour deposition (PECVD) and printing of a few layers.
This figure is to be compared with 10 -6 g/m 2/day, a figure for WVTR that is widely accepted as a minimum requirement for commercial devices. At this level, it is expected that it would take over 10 years for deterioration due to moisture to lead to visible black spots on the OLED.
"Such a rating is difficult to achieve, and many other flexible OLEDs with single-layer barriers have around 10 -5 g/m 2/day or higher (equivalent to a 1 year lifetime or less)", notes Hylke Akkerman, Senior Scientist at Holst Centre.
"Beating the 10 -6 g/m 2/day target with such a simple structure shows the excellent protection of Thin E-Strate and Holst Centre's direct thin film encapsulation stack on top."
Visit the Holst Centre at www.holstcentre.com