Nature455, 956-959 (16 October 2008) | doi:10.1038/nature07320; Received 1 February 2008; Accepted 7 August 2008
Bottom-up organic integrated circuits
Edsger C. P. Smits1,2,3, Simon G. J. Mathijssen2,4, Paul A. van Hal2, Sepas Setayesh2, Thomas C. T. Geuns2, Kees A. H. A. Mutsaers2, Eugenio Cantatore5, Harry J. Wondergem2, Oliver Werzer6, Roland Resel6, Martijn Kemerink4, Stephan Kirchmeyer7, Aziz M. Muzafarov8, Sergei A. Ponomarenko8, Bert de Boer1, Paul W. M. Blom1 & Dago M. de Leeuw1,2
Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands
Dutch Polymer Institute, PO Box 902, 5600 AX Eindhoven, The Netherlands
Department of Applied Physics,
Mixed-Signal Microelectronics Group, Department of Electrical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
Institute of Solid State Physics, Graz University of Technology, Petersgasse 16A, 8010 Graz, Austria
H. C. Starck GmbH, Chemiepark Leverkusen, Building B202, 51368 Leverkusen, Germany
Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Profsoyuznaya 70, 117393 Moscow, Russia
Self-assembly—the autonomous organization of components into patterns and structures1—is a promising technology for the mass production of organic electronics. Making integrated circuits using a bottom-up approach involving self-assembling molecules was proposed2 in the 1970s. The basic building block of such an integrated circuit is the self-assembled-monolayer field-effect transistor (SAMFET), where the semiconductor is a monolayer spontaneously formed on the gate dielectric. In the SAMFETs fabricated so far, current modulation has only been observed in submicrometre channels3, 4, 5, the lack of efficient charge transport in longer channels being due to defects and the limited intermolecular – coupling between the molecules in the self-assembled monolayers. Low field-effect carrier mobility, low yield and poor reproducibility have prohibited the realization of bottom-up integrated circuits. Here we demonstrate SAMFETs with long-range intermolecular – coupling in the monolayer. We achieve dense packing by using liquid-crystalline molecules consisting of a -conjugated mesogenic core separated by a long aliphatic chain from a monofunctionalized anchor group. The resulting SAMFETs exhibit a bulk-like carrier mobility, large current modulation and high reproducibility. As a first step towards functional circuits, we combine the SAMFETs into logic gates as inverters; the small parameter spread then allows us to combine the inverters into ring oscillators. We demonstrate real logic functionality by constructing a 15-bit code generator in which hundreds of SAMFETs are addressed simultaneously. Bridging the gap between discrete monolayer transistors and functional self-assembled integrated circuits puts bottom-up electronics in a new perspective.