Tuesday, 23 Jan 2018

OLED on ceramic opens up new possibilities for durable, flexible lighting and displays

This new structure needs just the ceramic substrate at the bottom and a thin film top encapsulation deposited by PECVD and printing of a few layers on top of the device

22 Sep 2016 | Editor

This new structure needs just the ceramic substrate at the bottom and a thin film top encapsulation deposited by PECVD and printing of a few layers on top of the device Most flexible OLEDs require double-sided multi-layer barriers

The Holst Centre and ENrG Inc. have created the first ever ceramic-based, large-area flexible OLED. The device, manufactured on the 20-40 µm thick Thin E-Strate ceramic substrate, promises a lifetime in excess of 10 years without the formation of blackspots.

The ceramic carrier is also easy to handle and capable of withstanding the high temperatures used in display backplane manufacturing and standard sintering processes.

The ceramic substrate used for the 12cm x 2.5cm prototype OLED device combines many of the best properties of other flexible OLED carriers.

It offers:

  • an intrinsic barrier to protect the sensitive OLED from the environment
  • easier to handle than either metal foils or flexible glass
  • like plastic films, the ceramic offers the potential for semi-transparent devices
  • its slight opaqueness actively improves light out-coupling, opening the door to higher devices efficiencies
  • unlike plastic films the ceramic can withstand temperatures up to 1000oC
Holst Centre/Enrg - OLED on flexible ceramic substrate

Figure: Holst Centre/Enrg - OLED on flexible ceramic substrate

The materials used to make OLEDs are extremely sensitive to the environment, in particular moisture, and must be protected on both sides. With its intrinsic barrier properties, Thin E-Strate means OLEDs can be fully protected with just the addition of a top barrier – simplifying production compared to plastic-based OLEDs.

The protection the OLED receives, and hence its potential durability, is typically quantified through its water vapor transmission rate (WVTR). In tests, the Thin E-Strate-based OLED demonstrated a WVTR below 8.5 x 10-7g/m2/day.

In addition, while most flexible OLEDs require a multi-layer barrier on both sides, the Holst Centre-ENrG device achieved these values thanks to just the ceramic Thin E-Strate at the bottom and a Holst Centre thin film top encapsulation, directly deposited by plasma enhanced chemical vapour deposition (PECVD) and printing of a few layers, on top of the device.

Kathy Olenick, Technical Marketing Manager at ENrG Inc, said, "Our Thin E-Strate ultra-thin ceramic has many plus points over other flexible OLED substrates. It is the only flexible substrate that has both intrinsic moisture barrier properties and high-temperature capabilities, in combination with being both robust and smooth enough to fabricate an OLED device on. The prototype device made by Holst Centre shows the benefits Thin E-Strate brings new flexible electronics applications."
Hylke Akkerman, Senior Scientist at Holst Centre, said, "A WVTR of less than 10-6g/m2/day is widely accepted as a minimum requirement for commercial devices. At this level, it takes over 10 years for deterioration due to moisture to lead to visible black spots. But such a rating is difficult to achieve, and many other flexible OLEDs with single-layer barriers have around 10-5g/m2/day or higher (equivalent to a 1year lifetime or less). Beating the 10-6g/m2/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. This approach could help further reduce complexity for flexible OLED production."

www.holstcentre.com    www.enrg-inc.com   

About Holst Centre

Holst Centre is an independent R&D center that develops technologies for wireless autonomous sensor technologies and for flexible electronics, in an open innovation setting and in dedicated research trajectories. A key feature of Holst Centre is its partnership model with industry and academia based around shared roadmaps and programs. It is this kind of cross-fertilization that enables Holst Centre to tune its scientific strategy to industrial needs.

Holst Centre was set up in 2005 by imec (Flanders, Belgium) and TNO (The Netherlands) and is supported by local, regional and national governments.

Located on High Tech Campus Eindhoven, Holst Centre benefits from, and contributes to, the state-of-the-art on-site facilities. Holst Centre has over 200 employees from some 28 nations and a commitment from over 50 industrial partners.

Source: Holst Centre

About Enrg Inc

ENrG markets and manufactures Thin E-Strate, an ultra-thin flexible fully dense zirconia based ceramic substrate. ENrG licensed this remarkable ceramic technology from Corning Incorporated. There are no other self-supporting ceramic membrane products on the market this thin, with the ability to flex and handle extreme transitions in temperature. Thin E-Strate redefines the world of ceramic membranes, available in traditional sheet form now and continuous rolls in 2017. ENrG believes industry trends including wearables, non-planar surfaces, and thinner and lighter weight are in play that provide for rapid market expansion for Thin E-Strate.

Source: Enrg Inc


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