Information technology has in a few decades changed our society radically, due to a very advanced scientific and technical development originating largely from fundamental scientific inventions in physics. In 1947 scientists at Bell Laboratories in the USA invented the first solid-state device that could amplify small signals – the transistor. Within a few years commercial products based on these devices became accessible to the public. The transistor is the (largely unseen) heart of our modern high-technology lifestyle, and has driven the computer revolution. Today chips contain tens of millions of separate transistors, at prices unchanged from the original transistors of 40 years ago. Just as the integrated circuit is a prime mover for electronic computer technology, ultra-rapid transistors and semiconductor lasers based on heterostructures of semiconductors are playing a decisive part in modern telecommunications. The importance of these developments was recognized by the Royal Swedish Academy of Sciences, which “decided to award the Nobel Prize in Physics for 2000 to scientists and inventors whose work has laid the foundation of modern information technology, IT, particularly through their invention of rapid transistors, laser diodes, and integrated circuits (chips).”

The element central to the microelectronics industry is silicon. In particular the ability to refine and produce large single crystals of ultra-high purity silicon has allowed devices to be miniaturised such that a Pentium-4 chip now contains over 40 million transistors. However, although ideal for many integrated electronics applications, single crystal silicon is not cheap, and the fundamental properties of silicon make it unsuitable for the majority of opto-electronics applications (e.g. for lasers used in optical communications). The use of lower quality amorphous silicon avoids the costs associated with single crystal silicon, and is suitable for cheap information-storing devices like smart cards and inventory control tags.  However amorphous silicon requires a glass substrate to “grow” on, which is not exactly ideal for a product to keep in your wallet, or for robust display screens of laptop computers. Furthermore it is still incompatible with most opto-electronic devices. That is why there is a growing scientific movement afoot to build circuits made from entirely new materials – organic plastics.

“Forget about the rigid materials of old. Now it's all about plastic.” Plastic devices have real advantages: In addition to being lighter and more rugged, plastic semiconductors are have enormous potential for optoelectronic applications, and would be significantly cheaper to produce than both single crystal and amorphous silicon equivalents. This is shown graphically in Fig.1, where a complete integrated circuit made from organic transistors has been produced on a flexible plastic substrate that can be bent and twisted – treatment that that would destroy rigid silicon devices.

There's just one problem: Plastic is generally accepted to be a very poor conductor of electricity – in fact, it's almost always considered an insulator. But in the late 1970’s three scientists (Heeger, MacDiarmid, and Shirakawa) demonstrated that plastic can be made to conduct electricity by manipulating its molecular structure, and shared the 2000 Nobel Prize in Chemistry for their groundbreaking work. Building on their findings, researchers continue to make advances at other institutions such as Lucent's Bell Labs, Cambridge, IBM, Princeton, and Xerox PARC. These advances are directly reflected in the speed with which plastic transistors can switch on and off; the property engineers call charge mobility. Every 18 months the charge mobility of transistors made from organic materials increases by a factor of ten, and is now at the point where it competes with amorphous silicon, at a fraction of the cost.

The field of organic semiconductors is poised to become the focus of major research activities, both internationally and here in Australia with a consortium of major universities (UNSW, Queensland, Newcastle and Wollongong).