Researchers at the University of Pittsburgh have invented a new type of electronic switch that performs electronic logic¹ functions within a single molecule². The incorporation³ of such single-molecule elements could enable smaller, faster, and more energy-efficient electronics. The research findings, supported by a $1 million grant from the W.M. Keck Foundation, were published online in the Nov. 14 issue of Nano Letters. "This new switch is superior to（优越于） existing single-molecule concepts," said Hrvoje Petek, principal investigator⁴ and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. "We are learning how to reduce electronic circuit elements to single molecules⁵ for a new generation of enhanced and more sustainable technologies."

The switch was discovered by experimenting with the rotation⁶ of a triangular⁷ cluster of three metal atoms held together by a nitrogen atom, which is enclosed（附上） entirely⁸ within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation⁹ of electrons. This rotation changes the molecule's ability to conduct an electric current, thereby¹⁰ switching among multiple logic states without changing the spherical¹¹ shape（球形） of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.

Because of their constant spherical shape, the prototype molecular¹² switches can be integrated（整合） as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing¹³ architectures.

The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper¹⁴ oxide¹⁵ substrate and an atomically sharp tungsten（钨） tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.

The research was led by Petek in collaboration¹⁶ with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People's Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt's Department of Physics and Astronomy.