Polymer colour matching devices (POCOMAT)

Organic TFTs have been developed for a broad range of display and integrated circuit applications on flexible, plastic substrates. For display applications organic TFTs have reached an advanced stage of industrialisation. Our industrial partner, Plastic Logic, manufactures flexible displays comprising more than 1 million OTFTs on a plastic substrate for applications in lightweight, robust electronic readers. In contrast to displays circuit applications of OTFTs have been much harder to realize. This is mainly due to the poor switching performance of printed OTFTs arising as a consequence of the relatively low mobility of organic semiconductors (which in spite of dramatic improvements in recent years is still "only" on the order of 1 cm2/Vs) and the low resolution of common graphic arts based printing techniques. Our approach to overcome the critical performance issues of printed electronics has been to develop a high-resolution printing-based manufacturing process for OTFTs (self aligned printing (SAP) / self-aligned gate (SAG) technology) (Noh et al., Nature Nanotechnology 2, 784 (2007)), which allows fabrication of TFTs with submicrometer channel lengths and low parasitic gate capacitance by simple inkjet printing techniques. In the EPSRC/CIKC funded PRIME project we developed this technology into a controlled technology platform for fabrication of integrated circuits with typically 100 TFTs. The number of TFTs is limited by our university fabrication and testing infrastructure. The PRIME project had two main technological objectives: (a) to establish manufacturability of the previously developed SAP/SAG process for downscaling printed organic TFTs and (b) to integrate both p-type and n-type organic semiconductors into such downscaled, printed TFTs to allow fabrication of high yielding, low power printed CMOS circuits. The objective of the proposed follow-on funding project is to commercialize this technology platform in a specific integrated circuit application that is compatible with the limited integration level that we can realistically achieve with our current fabrication infrastructure (about 100 elements).

The immediate impact of the follow-on project will be to enable us to commercialize the technology developed in the PRIME project in a non-display/circuit application. With the colour matching application we have identified an application that is both compatible with the current, realistically achievable level of integration for the PRIME technology, but also represents a concrete, attractive application opportunity which could be commercialized in a short to medium timescale. The follow-on funding will enable us to fabricate a demonstrator which will demonstrate the full functionality of an integrated plastic electronic colour matching device in the context of a toy application. Such a demonstrator will have significant value in terms of engaging with and inspiring the imagination of potential application partners and convincing a financial investor that there are real, near-term business opportunities for this plastic electronic technology. In the present financial climate it would be near impossible to attract investment for a company aiming to develop plastic electronic technology for a yet to be demonstrated application. What we need is a demonstration with full functionality in the context of a concrete application. The follow-on funding will enhance significantly our chances of being able to engage seriously with industrial partners and commercialise the PRIME technology within the timeframe of the follow-on project.

The project would also have a significant impact on the wider development of the plastic electronics industry in the UK. The UK has traditionally had a leadership position in this field at both an academic and industrial level. UK academic groups at Imperial College, Oxford, Warwick, Cambridge, Durham, Manchester, Cardiff and Liverpool are among the internationally leading groups in the field and have pioneered several of the key developments in the field. Industrial companies, such as DuPont Teijin Films, Merck, SmartKem, CDT, Polyphotonix, Plastic Logic, Eight19, Solar Press, Oxford Photovoltaics have been leading the industrial development of organic materials, OLEDs and OTFTs for display applications and of organic solar cells, respectively. These constitute first generation applications of plastic electronics. However, the UK is lacking a competence in system integration of organic semiconductor technology, i.e. at present no industrial company nor academic institution in the UK has the capability to integrate more than a few TFTs into a logic circuit or integrate TFT circuits with other plastic elements to produce a multifunctional integrated circuit. This is a worrying situation, given that other institutions, such as Holst, are gaining a lead with such circuit integration capability. We realized this some years ago and this is the reason why in the PRIME project we have focussed our limited resources on developing such an integration platform based on our downscaled, printing approach.

The UK strategy to capitalise on the wider plastic electronics opportunity and capitalise on the printable electronics market ($57bn by 2019; IDTechEx) relies on development of the supply chain within the UK. This project is a response to the UK strategy, addressing an important supply chain gap in the integration of plastic electronic logic circuits.