Researchers develop the first plastic superconductor

Scientists from Bell Labs have created the world’s first plastic material in which resistance to the flow of electricity vanishes below a certain temperature.

Scientists from Bell Labs have created the world’s first plastic material in which resistance to the flow of electricity vanishes below a certain temperature, making it a superconductor.

The plastic, described in today’s issue of Nature, is an inexpensive material that could be widely used in the future for applications, such as quantum computing and superconducting electronics.

The Bell Labs breakthrough comes after a 20-year quest to find organic polymers that act as superconductors.

Organic polymers are chemical molecules that contain a long string of carbon atoms and make versatile plastics. While organic polymers that conduct electricity have been around since the 1970s – last year’s Nobel Prize for Chemistry, for instance, went to the researchers who discovered plastic conductors, which are organic materials that have some resistance to the flow of electricity – creating a superconducting organic polymer proved to be far more difficult. The challenge in creating a plastic superconductor was overcoming the inherent structural randomness of a polymer – similar to strands of cooked spaghetti – which prevented the electronic interactions necessary for superconductivity.

The Bell Labs scientists were able to overcome this by making a solution containing the plastic, polythiophene. They then deposited thin films of it onto an underlying layer so that the polymer molecules stacked up against one another like uncooked spaghetti. Instead of adding chemical impurities to change the material’s electrical properties, as is often done, the researchers used a novel technique in which they removed electrons from polythiophene. The temperature below which polythiophene became superconducting was minus 455 degrees Fahrenheit. Although this is extremely cold, scientists are optimistic that they can raise the temperature in the future by altering the molecular structure of the polymer.

Polythiophene, which can be a conductor at room temperatures and which has been used previously in making optoelectronic components and smart pixels, may be the first of many superconducting plastics.

‘With the method we used, many organic materials may potentially be made superconducting now,’ said Zhenan Bao, a Bell Labs chemist who was involved in the research.

Bell Labs scientists plan to study the inter-relationships between semiconducting, superconducting and molecular electronics with materials such as polythiophene in the coming months. ‘A new window into nature has opened up,’ said Ananth Dodabalapur, a device physicist at Bell Labs and member of the research team, talking of the implications of the breakthrough.

Besides Bao and Dodabalapur, Bell Labs scientists involved in the research were Hendrik Schon, Christian Kloc and Bertram Batlogg. A collaborator from the University of Konstanz in Germany, Ortwin Schenker, also participated in the research. In addition to Bell Labs, Batlogg is affiliated with the solid state physics laboratory at ETH Honggerberg in Switzerland.

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