The observation of truly metallic behavior in an organic material heralds a new generation of electronic devices

February 15, 2013
Figure 1: The crystal structure of the organic metal (BEDT-TTF)3Br(pBIB) in real space (left) and a rendering of the ‘wave-number space’ (right), representing the space where conducting electrons exist. Credit: 2012 Nature Publishing Group (left); Reizo Kato, RIKEN Condensed Molecular Materials Laboratory (right)

When we think about metals, objects like copper wires and sheets of iron spring to mind. However, organic materials—those based, as all living matter, on carbon and oxygen atoms—can also exhibit metallic behavior. Some organic compounds have been established as good electric conductors, but these systems can be full-fledged metals as Reizo Kato of the RIKEN Advanced Science Institute, Wako, and co-workers in Japan and China have shown. They found unambiguous signatures in an organic compound which establish that the material behaves at low temperatures precisely like most metals.

The interest in 'organic metals' is fuelled by the prospect of technological applications reaching from stretchable electronics to bio-integrated devices. However, almost 40 years after the first discovery of organic metals, a number of fundamental aspects remain to be explored in these materials. In particular, until now it has never been shown that organic metals behave according to the so-called Fermi-liquid theory—the model that describes the behavior of most metals at low temperatures.

Kato and his colleagues have filled this gap. The team observed the signatures of a Fermi liquid in a compound known as (BEDT-TTF)3Br(pBIB) (Fig. 1, left). "In general, organic conductors are fragile and vulnerable to light irradiation," says Kato. "But over a period of more then ten years our team has made methodological advances—in particular in the area of photoelectron spectroscopy—that allowed us to reduce the disruptive factors." The team's know-how enabled them to successfully conduct a series of experiments in which they showed that at low temperatures the electrons in (BEDT-TTF)3Br(pBIB) indeed behave in the same characteristic manner as they do in a conventional metal (Fig. 1, right).

These findings call for revisiting a number of earlier experiments that indicated that the electrons in organic materials behave differently from a Fermi liquid. But most importantly, the work of Kato and his colleagues provides a sound foundation for understanding organic metals, which in turn should pave the way toward practical applications. "This project will provide important information for understanding electronic processes and designing organic materials," says Kato. Among the organic metals, the (BEDT-TTF)3Br(pBIB) system and related compounds are particularly interesting as they are characterized by an architecture in which two-dimensional conducting layers are separated by insulating supramolecular networks. Such network structures may serve as the building blocks for functional molecular materials, including computing and memory elements for electronic devices.

Explore further: Scientists advance facile synthesis of nanoparticles with multiple functions

More information: Kiss, T., et al. Quasiparticles and Fermi liquid behaviour in an organic metal. Nature Communications 3, 1089 (2012).

Related Stories

The origin of organic magnets

March 2, 2012

Electrical engineers are starting to consider materials made from organic molecules -- including those made from carbon atoms -- as an intriguing alternative to the silicon and metals used currently in electronic devices, ...

Taking a closer look at molecular electronics

March 9, 2012

Molecules and polymers have unique electronic and optical properties suitable for use in electronic devices. These properties, however, are complex and not well understood. Charge transport, for example, is affected by molecule ...

Stable electrodes for improving printed electronics

April 19, 2012

Imagine owning a television with the thickness and weight of a sheet of paper. It will be possible, someday, thanks to the growing industry of printed electronics. The process, which allows manufacturers to literally print ...

Elusive metal discovered

August 22, 2012

Carnegie scientists are the first to discover the conditions under which nickel oxide can turn into an electricity-conducting metal. Nickel oxide is one of the first compounds to be studied for its electronic properties, ...

Recommended for you

Force triggers gene expression by stretching chromatin

August 26, 2016

How genes in our DNA are expressed into traits within a cell is a complicated mystery with many players, the main suspects being chemical. However, a new study by University of Illinois researchers and collaborators in China ...

Isolation of Fe(IV) decamethylferrocene salts

August 29, 2016

(—Ferrocene is the model compound that students often learn when they are introduced to organometallic chemistry. It has an iron center that is coordinated to the π electrons in two cyclopentadienyl rings. (C5H5- ...

Bringing artificial enzymes closer to nature

August 29, 2016

Scientists at the University of Basel, ETH Zurich, and NCCR Molecular Systems Engineering have developed an artificial metalloenzyme that catalyses a reaction inside of cells without equivalent in nature. This could be a ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.