SEmicoNducting SupramOlecular nanoscale wiRes and Field-Effect TransistorS (SENSORS)

Lead Research Organisation: University College London
Department Name: London Centre for Nanotechnology

Abstract

SENSORS aims to generate new knowledge to underpin the development of new interfacing protocols for nanoscale organic logics. SENSORS relies on supramolecular approach to the design, synthesis and use of solution-processable Supramolecularly Engineered Nanostructured Materials (SENMs) with electronic function, to seek new solutions for solving key interfacing issues of wires and transistors prototypes (molecular-/meso-scale).
 
Description Patterning of semiconducting polymers on surfaces is important for various applications in nanoelectronics and nanophotonics. However, many of the approaches to nanolithography that are used to pattern inorganic materials are too harsh for organic semiconductors, so research has focussed on optical patterning and various soft lithographies. Surprisingly little attention has been paid to thermal, thermomechanical and thermochemical patterning. We have demonstrated the thermochemical nanopatterning of poly(p-phenylene vinylene), a widely used electroluminescent polymer, by a scanning probe. Interestingly we were able to demonstrate, for the first time, that it was possible to produce patterned structures with dimensions below 28 nm (full-width at half-maximum), even with micron-sized probes (diameter of 5µm of the Wollaston wire used for this experiments). We also achieved write speeds of 100 µm/s. Our experiments have shown that a resolution of 28 nm is possible when the tip-sample contact region has dimensions of 100 nm or so, and we have predicted with the aid of finite-element modelling that the resolution could be improved by using thinner films and smaller probes with an optimised design (for example, micromachined doped silicon probes). These results could pave the way to direct thermochemical fabrication of a variety of electronic and photonic devices made from organic semiconductors, including nanoscale light-emitting diodes for single-photon emission and quantum cryptography applications. This work has been published in Nature Nanotechnology in September/October 2009.

The work above has been complemented by advanced in the fabrication of high-resolution nanostructures in both poly( p -phenylenevinylene), PPV, and a crosslinkable derivative of poly(9,9 ' -dioctylfluorene), F8, using scanning near-fi eld optical lithography, is reported. The ability to draw complex, reproducible structures with 65000 pixels and lateral resolution
below 60 nm ( < ? /5) was demonstrated over areas up to 20 µm × 20 µm. Patterning on length-scales of this order is desirable for realising applications both in organic nanoelectronics and nanophotonics. The technique is based on the site-selective insolubilization of a precursor polymer under exposure to the
confi ned optical fi eld present at the tip of an apertured near-fi eld optical fiber probe. In the case of PPV, a leaving-group reaction is utilized to achieve insolubilization,whereas the polyfl uorene is insolubilized using a photoacid initiator
to create a crosslinked network in situ. For PPV, resolubilization of the features is observed at high exposure energies. This is not seen for the cross-linked F8 derivative, r-F8Ox, allowing us to pattern structures up to 200 nm in height.
Exploitation Route Soon after publication of our work on there has been a number of papers published in the literature about scanning thermochemical lithography, witnessing the potential of this area, and a start-up has even been spun off by IBM Zurich (Swiss litho), now commercialising advanced versions of scanning thermal AFMs for lithography.
Sectors Electronics

 
Description Global Excellence
Amount £489,807 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2012 
End 03/2013
 
Description Large collaborative project
Amount € 386,000 (EUR)
Funding ID ONE-P 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2009 
End 12/2011
 
Description Leverhulme trust research grant
Amount £245,618 (GBP)
Organisation The Leverhulme Trust 
Sector Academic/University
Country United Kingdom
Start 07/2013 
End 09/2016
 
Description MC ITN - 2012
Amount € 640,000 (EUR)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 10/2011 
End 09/2015
 
Description MSCA ETN - 2014 - i-Switch
Amount € 256,778 (EUR)
Funding ID i-switch 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2015 
End 12/2018
 
Description Delft University of Technology 
Organisation Delft University of Technology (TU Delft)
Country Netherlands 
Sector Academic/University 
Start Year 2005
 
Description Linkoping UNI Sweden 
Organisation Linkoping University
Country Sweden 
Sector Academic/University 
Start Year 2005
 
Description University of Cambridge 
Organisation University of Cambridge
Country United Kingdom 
Sector Academic/University 
Start Year 2007
 
Description University of Oxford 
Organisation University of Oxford
Country United Kingdom 
Sector Academic/University 
Start Year 2005
 
Description University of Oxford 
Organisation University of Oxford
Country United Kingdom 
Sector Academic/University 
Start Year 2005