A surface-anchored molecular four-level conductance switch based on single proton transfer

Willi Auwärter, Knud Seufert, Felix Bischoff, David Ecija, Saranyan Vijayaraghavan, Sushobhan Joshi, Florian Klappenberger, Niveditha Samudrala, Johannes V. Barth

Research output: Contribution to journalArticlepeer-review

235 Scopus citations


The development of a variety of nanoscale applications1,2 requires the fabrication and control of atomic or molecular switches 6,7 that can be reversibly operated by light, a short-range force9,10, electric current11,12 or other external stimuli. For such molecules to be used as electronic components, they should be directly coupled to a metallic support and the switching unit should be easily connected to other molecular species without suppressing switching performance. Here, we show that a free-base tetraphenyl-porphyrin molecule, which is anchored to a silver surface, can function as a molecular conductance switch. The saddle-shaped molecule has two hydrogen atoms in its inner cavity that can be flipped between two states with different local conductance levels using the electron current through the tip of a scanning tunnelling microscope. Moreover, by deliberately removing one of the hydrogens, a four-level conductance switch can be created. The resulting device, which could be controllably integrated into the surrounding nanoscale environment, relies on the transfer of a single proton and therefore contains the smallest possible atomistic switching unit.

Original languageEnglish
Pages (from-to)41-46
Number of pages6
JournalNature Nanotechnology
Issue number1
StatePublished - Jan 2012


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