Midwife to the Birth of Organic Electronics

In 1972 I left a fine job as a professor of physics at the University of Illinois at Urbana-Champaign to come to the Xerox Corporation in Webster, New York. Xerox was in its heyday: at the time it was the fastest-growing firm in the history of the New York Stock Exchange. But troubles were on the horizon. A consent decree in 1975 opened the company’s patent portfolio to all comers, and in the three years since I had arrived, its stock had fallen from $172 to $50 per share.

My hiring manager was assigned the task of starting a new chemistry laboratory in Canada (which became the Xerox Research Centre of Canada in 1974), and I was assigned his job of managing materials research in Webster, as well as planning the technology futures for copier-duplicator businesses. The creation of a new generation of xerography on which Xerox could obtain new patent protection became a prime focus of both efforts, because it would allow Xerox to stave off the competitive assault from Eastman Kodak and IBM in the United States and from numerous Japanese firms attracted by the consent decree. The effort to create a new generation of xerography led to the birth of organic electronics as a new technology-led industry. The path to this new industry ran straight through the Gordon Research Conferences.

The xerographic process involves several steps: charging an insulating drum; creating a charged image by exposing the drum to light; developing the image with charged, pigmented powder (toner); transferring this powder image to paper; and then fusing the image onto the paper with heat and pressure. First- and second-generation xerography, the subjects of Xerox’s patents before 1975, used metal drums or belts coated with amorphous selenium or arsenic-selenium alloys.

For the third generation of xerography we envisaged using flexible organic belts. They would be cheaper, and we would be able to wrap them around small rollers to form flat areas suitable for full-frame flash exposure. This would permit high-speed copying using small console machines instead of large machines that embodied massive drums or belts. But there was one small problem: the flexible organic materials of the day trapped photo-injected charges, and the resulting photoreceptors had very limited lives.

The solution was a drive to develop organic materials for electronic applications. The materials would have controllable electrical properties and would behave like familiar network inorganic semiconductors but would be flexible, cheap, and easy to fabricate. At the same time major universities were engaging in research on “quasi one-dimensional” crystalline semiconductors, most of which were organic. Xerox also started a research program in this area to couple our organic solid-state re-search with this vibrant academic effort.

The two streams of activity came together in 1977 with back-to-back conferences. The Chemistry and Physics of Solids Gordon Research Conference met in Plymouth, New Hampshire; immediately following, a special New York Academy of Science conference called Synthesis and Properties of Low-Dimensional Materials met in New York City. Dwaine Cowan, of Johns Hopkins University, and I co-organized the GRC conference, and two other Xerox scientists, Joel Miller and Art Epstein, organized the one in New York. Previously, research efforts into the synthesis, theory, and properties of electronic organics had been separated, but these meetings brought them together as a coherent group. They also brought together participants from a variety of firms, academic institutions, and disciplines that had seldom participated in the same forums in the past.

Within a few years this rich mix of people and ideas led to two important breakthroughs. First, it became evident that the organic polymers that best exemplified semiconductive properties were not organic semiconductors in the context of solid-state energy band theory. Rather, they were best described using disorder-induced localized state models, which predicted design rules for photoconductors and toners that were dramatically different from the rules based on energy band theory in use at the time. Within a decade the new models led to the design and fabrication of large-area photoreceptor belts and an organic xerographic materials industry that generated a billion dollars per year. Second, the notion of doping or-ganic polymers with atoms and small molecules (adding materials to facilitate conductivity), a practice already prevalent in the photoconductor industry, was extended to other (degenerate ground state) polymers. This in turn created the field of organic synthetic metals, for which Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa won the Nobel Prize in chemistry in 2000.

The Organic Thin Films and Surfaces GRC I organized in Ventura, California, in the winter of 1983 further ex-tended the momentum created in 1977. Numerous applications of organic electronics were explored at this conference–including large area displays, plastic batteries, semiconductor processing, solar energy, optical storage, electro-optics, photography, and electrophotography–by a diverse group of industrial and university scientists who seldom met in other forums. Chemists and physicists mingled intimately. Alan Heeger led a session on organics in energy and electrochemistry. The discussion topics presaged contemporary efforts in organic light-emitting diodes, flexible displays, and printed organic electronics.

Unfortunately, there was not enough economic incentive for industry to invest in the production technologies for organic electronic applications other than photography and electrophotography. Few people realize that xerographic photoreceptors are as complex as large-scale silicon integrated circuits but are fabricated by the square mile rather than by the square centimeter. But the re-searchers did not give up; in fact, many of the players in the early Gordon Conferences in this area are still prominent leaders in the development of organic electronics materials and devices.

The birth of organic electronics illustrates the immense intellectual and economic benefits that result from a free flow of technical information. Individual scientists gained access to model concepts, experimental measurement techniques, and methods of materials fabrication practiced in only the most advanced academic and industrial laboratories of the day. They encountered opportunities for new collaborations that often took the field in unanticipated directions. Xerox and other firms obtained insight into and validation of design principles that yielded specific copier products and materials of considerable economic value. This led to industry growth: new jobs and capital investment spread widely throughout the associated business communities. The Gordon Conferences facilitated these results by providing forums for off-the-record exchanges organized and led by both industry and academic scientists. The openness and intensity of Gordon Conferences aided enormously in creating intellectual and commercial value. GRC was the midwife at the birth of the organic electronics industry, contributing directly to both the intellectual and economic vigor of the United States.