In the EPSRC funded project (2003-2006) with Dupont Teijin Films Ltd, Prof Placido and post-graduate researchers (Sarfaraz Moh, David Lusk and Andrei Voronov) developed the first pinhole-free, dielectric ultra-barrier coatings on novel heat-stabilised, planarised PEN substrates. These coatings survived the now standard calcium test for water vapour permeation for 1000 hrs at 99% RH and 50°C. This coating is particularly relevant to organic light emitting diode (OLED) materials but also to other organic semiconductors that require some degree of protection from water vapour.
The 2004-2007 DTI LINK funded project with DTF and Plastic Logic successfully demonstrated the first working all-polymer display, using planarised PET from DTF and prototype backplane facilities at PL.
The same partners later demonstrated the world’s first all-polymer A4 size e-book reader.
A significant outcome deriving from Prof Placido’s previous work on aluminium nitride thin films was the demonstration that the metallisation layers in the backplane could be reliably fabricated from aluminium nitride and a very thin (50 nm) gold coating. This led to a great simplification in the production process, saving time and cost through the elimination of the usual adhesion promoting layer of titanium, nickel or chromium and also providing a barrier layer against water vapour.
Significant beneficiaries of this research are the companies involved, firstly Dupont Teijin Films Ltd, having acquired a world leading position in the supply of planarised and heat-stabilised polymers for the developing plastic electronics industry. According to the DTF source (submitted letter) “the work in the programme also helped in both the understanding of the property benefits of specialty planarised films; which have formed the basis of DTF’s portfolio of products for the flexible display industry and in forming a view on whether thin film deposition offered an opportunity for DTF”. The same source confirms that the later work with TFC and PL Ltd “has led to significant sales of a planarised film product for DTF”.
Secondly, Plastic Logic Ltd has benefited from very considerable external investment having validated its polymer TFT technology, with the first feasibility study securing >$100M investment and allowing PL Ltd to build in Dresden the first-ever manufacturing facility for flexible displays (Confirmation in submitted letter from CTO, PL Ltd) and in the later EPSRC/LINK project (2007-2010). PL Ltd now has manufacturing facilities in Dresden and also in south Moscow.
In the wider sense, the commercial availability of proven heat-stabilised, planarised polymer substrate material from DTF Ltd is of significant benefit to the world-wide manufacturers of devices based on lightweight, flexible substrates, including displays and solar cells.