1. Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974, USA
2. Lucent Technologies, 555 Union Boulevard, Allentown, Pennsylvania 18103, USA
3. Present address: Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Correspondence to: A. Dodabalapur¹ Correspondence and requests for materials should be addressed to A.D. (e-mail: Email: ananth@bell-labs.com).

Thin-film transistors based on molecular and polymeric organic materials have been proposed for a number of applications, such as displays^{1, 2, 3} and radio-frequency identification tags^{4, 5, 6}. The main factors motivating investigations of organic transistors are their lower cost and simpler packaging, relative to conventional inorganic electronics, and their compatibility with flexible substrates^{7, 8}. In most digital circuitry, minimal power dissipation and stability of performance against transistor parameter variations are crucial. In silicon-based microelectronics, these are achieved through the use of complementary logic—which incorporates both p- and n-type transistors—and it is therefore reasonable to suppose that adoption of such an approach with organic semiconductors will similarly result in reduced power dissipation, improved noise margins and greater operational stability. Complementary inverters and ring oscillators have already been reported^{9, 10}. Here we show that such an approach can realize much larger scales of integration (in the present case, up to 864 transistors per circuit) and operation speeds of 1 kHz in clocked sequential complementary circuits.