Heeger, Alan J.

Heeger, Alan J., born in 1936, American physical chemist and cowinner of the 2000 Nobel Prize in chemistry. Heeger received the Nobel Prize along with Japanese chemist Hideki Shirakawa and Alan G. MacDiarmid, a New Zealand-born American chemist, for the discovery and development of polymers that conduct electricity. Polymers are large molecules comprising many smaller repeating patterns of atoms strung together in a long chain. In the late 1970s Heeger and his colleagues discovered that plastics and other polymers, if properly modified, can conduct an electrical charge in a manner similar to metals and other standard conducting materials. This work launched the field of polymer-based electronic research. Building on the advances of Heeger and his coworkers, scientists today are developing polymer conductors and semiconductors for many applications.

Born in Sioux City, Iowa, in 1936, Heeger graduated from the University of Nebraska in 1957 and earned his doctoral degree in 1961 from the University of California, Berkeley. In 1962 he joined the faculty of the University of Pennsylvania, Philadelphia, working there until 1982, when he became a professor of physics at the University of California, Santa Barbara. In 1990 Heeger founded UNIAX Corporation, a company that develops commercial applications for conducting polymers.

In 1975 at the University of Pennsylvania, Heeger and MacDiarmid collaborated in modifying the properties of sulfur nitride, a polymer. During this work, the two scientists created a thin film made of the substance. MacDiarmid happened to mention the film while giving a talk at a scientific meeting in Tokyo, Japan. During a coffee break, MacDiarmid was approached by Shirakawa, who was conducting his own research on polymers at the Tokyo Institute of Technology. Shirakawa told MacDiarmid that he too had created a polymer-based film, the accidental result of too much catalyst added to a mixture of the polymer polyacetylene. MacDiarmid invited Shirakawa to join him and Heeger at the University of Pennsylvania to investigate these polymer films.

The three scientists experimented with adding and removing electrons from the polyacetylene—a process known as doping. When they diffused iodine into the polymer, the team was surprised to observe that the substance’s electrical conductivity increased by a factor of 10 million. The iodine, in effect, had loosened the densely packed electrons in the polyacetylene, allowing the material to carry an electric charge. Heeger, MacDiarmid, and Shirakawa published their results in 1977, launching a worldwide effort to pursue the new technology of conducting polymers.

A new era of electronics based on conducting polymers has begun. These materials are less expensive, more flexible, and easier to work with than conventional conductors. The conducting polymers are being developed for use in displays for cell phones and other handheld devices, flat-screen televisions, and video displays so flexible they can be folded. One day, miniaturized polymer-based circuitry will likely serve as the basis of new computers, with individual organic molecules performing the work now done by silicon chips.