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Techniques for manufacturing organic electronic devices [organic light-emitting diodes (OLEDs), photovoltaic cells, transistors, and solid-state memory] are reviewed and analyzed with respect to cost and market fitness in comparison to competitive approaches based on silicon electronics. The conclusions are (i) OLED displays will be successful using infrastructure largely borrowed from liquid crystal displays, because they provide fundamental customer value not dependent on lower cost; (ii) OLEDs for general lighting and organic–inorganic hybrid photovoltaic cells currently confront substantial barriers in cost and efficiency, but solutions appear feasible and would lead to very large volume businesses; (iii) organic crossbar memories are promising, but require innovations in driver architecture and interconnection; and (iv) organic transistors have not yet found a viable major market, but have great promise for highly customized, small-volume product runs using digital patterning techniques.

I. INTRODUCTION

The first example of a macroscopic electrical effect (i.e., an effect involving charge conduction that might be used in a practical electronic device) in solid-state organic materials was electroluminescence, first observed in molecular crystals during the 1960s when the foundations of our current knowledge of electronic excitations, energy transport, and photochemistry were all laid.1 About four decades later, although the research effort is burgeoning,2 the only commercial products are photocopier photoconductors and organic light-emitting diodes (OLEDs). Even the latter is still a nascent industry, typified by Pioneer’s automobile radios and Philips’ electric shaver (although several major production facilities are in development, and cell phone and camera displays have begun to appear in limited venues). Certainly, there remain important materials issues involved in the development of saleable devices from organic materials; these will have been well covered in other articles in this special issue. Our focus here will be on manufacturing, which is inextricably intertwined with understanding product needs. This is a subject not often addressed in scientific journals (for good reason), but electronics is by definition an engineering topic. Basic research into structures and mechanisms is always potentially useful and is judged by other criteria. However,

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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0275 1974

http://journals.cambridge.org

J. Mater. Res., Vol. 19, No. 7, Jul 2004 Downloaded: 15 Mar 2015

research devoted to the development of ostensibly saleable devices and the improvement of their performance values or cost of fabrication cannot be appropriately evaluated without an understanding of their market potential and constraints. This review will consider four types of devices that are widely studied today: light emitters (LEDs), light harvesters (photovoltaics), and purely electronic devices (transistors and memory). With respect to each of t