Flexible barrier and encapsulation technologies improve the shelf life of devices such as flexible OLED lighting and OPVs from moisture ingress particularly, which tend to cause the technology to degrade.
Requirements for plastic electronics are higher than other technologies as some devices will need a shelf life of several years, while the level of protection can also depend heavily on the application – barrier and encapsulation requirements for a flexible OPV device, used to power an indoor sensor system, will be different to a flexible OLED lighting product, which will differ to an outdoor building- integrated PV (BIPV) application for an OPV panel. In addition high barrier technologies for plastic electronics have to be manufactured cost-effectively.
Plastic electronics R&D clusters in Europe are beginning to make headway in this area. In 2010 plasma-enhanced chemical vapour deposition (PECVD) technology equipment supplier Roth & Rau Microsystems joined the Holst Centre‘s large area flexible electronics programme, specifically to work on roll-to-roll (R2R) deposition tools for transparent high barrier layers.
OLED lighting devices using the batch-processed thin film flexible barrier technology have been validated in accelerated lifetime tests, while Roth & Rau Microsystems continue to scale the process for R2R.
The Holst Centre’s PECVD barrier technology is also being used in the Solliance project, of which Holst Centre is a founding R&D partner, as a baseline process, for flexible solution processable OPVs, though other barrier technologies and processes that have the potential to be more cost-effective are also being investigated.
In the UK, the Centre for Process Innovation (CPI) is working closely with atomic layer deposition (ALD) tool supplier Beneq. The partners will, together, develop an industry-ready transparent high-barrier/encapsulation process that can be applied using an R2R ALD tool that the CPI has bought from Beneq.
In future, might this mean that the CPI and Beneq are able to collaboratively offer barrier technologies to the plastic electronics industry – Beneq the production tool and CPI the know-how – which may differ depending on devices and applications for devices. Potentially barriers can be applied in several ways, including supplied as a standalone transparent film product that can be laminated onto a device, applied directly onto a device, or applied as a layer on to a film/foil substrate that devices are made on. Investigation and development of these will be done by the CPI.