Polymeric and Organic Electronic Materials: From Scientific Curiosity to Applications

Extract

While polymers and organic materials have been known and utilized broadly for many decades, finding such materials with the intrinsic properties of semiconductors and metals is a relatively recent phenomenon. The report in 1977 about doping polyacetylene to achieve relatively high conductivity opened up important new vistas for chemistry and physics, and for technology in general. This report recognized that a key feature of the electronic polymers and organic materials was a backbone consisting of alternating single and double bonds resulting in a “π-conjugated network.” This in turn led to a relatively small energy gap, enabling the appearance of both semiconducting and metallic properties.

Initially these polymers were unstable in air and not readily processed. Over the past decade, major advances have occurred in the synthesis of new forms of conducting and semiconducting polymers that enable processing under a broad range of conditions including organic solvents, inorganic solvents, and aqueous media. There are even meltprocessable versions of some of the electronic polymers.

A prime focus of the field has been the determination of the mechanisms for charge conduction and the intrinsic conductivity of these fascinating materials, especially doped polymers. In the past decade, interest has increased in the semiconducting (generally undoped) forms of these polymers and organic materials, including their photophysics and their use in a wide variety of devices. The reports of light-emitting devices fabricated from molecular and oligomeric constituents in the mid-1980s and from polymeric constituents in 1990 stimulated interest in this area of research.