Electronic systems that use rugged lightweight plastics potentially offer attractive characteristics (low-cost processing, mechanical flexibility, large area coverage, etc.) that are not easily achieved with established silicon technologies. This paper summarizes work that demonstrates many of these characteristics in a realistic system: organic active matrix backplane circuits (256 transistors) for large (Ϸ5 ؋ 5-inch) mechanically flexible sheets of electronic paper, an emerging type of display. The success of this effort relies on new or improved processing techniques and materials for plastic electronics, including methods for (i) rubber stamping (microcontact printing) high-resolution (Ϸ1 m) circuits with low levels of defects and good registration over large areas, (ii) achieving low leakage with thin dielectrics deposited onto surfaces with relief, (iii) constructing highperformance organic transistors with bottom contact geometries, (iv) encapsulating these transistors, (v) depositing, in a repeatable way, organic semiconductors with uniform electrical characteristics over large areas, and (vi) low-temperature (Ϸ100°C) annealing to increase the on͞off ratios of the transistors and to improve the uniformity of their characteristics. The sophistication and flexibility of the patterning procedures, high level of integration on plastic substrates, large area coverage, and good performance of the transistors are all important features of this work. We successfully integrate these circuits with microencapsulated electrophoretic ''inks'' to form sheets of electronic paper.T he backplane circuit consists of a square array of 256 suitably interconnected p-channel transistors. Fig. 1 shows the circuit layout. Fig. 2 presents a cross-sectional illustration of a transistor and a top view of a unit cell. The completed display (total thickness Ϸ1 mm) comprises a transparent frontplane electrode of indium tin oxide (ITO) and a thin unpatterned layer of flexible electronic ''ink'' mounted against a sheet that supports square pixel electrode pads and pinouts; these pixel pads attach, via a conductive adhesive, to the back planes. Each transistor functions as a switch that locally controls the color of the ink, which consists of a layer of polymeric microcapsules filled with a suspension of charged pigments in a colored fluid (1, 2). In each of the four quadrants of the display, transistors in a given column have connected gates, and those in a given row have connected source electrodes. Applying a voltage to a column (gate) and a row (source) electrode turns on the transistor located at the cell where these electrodes intersect. Activating the transistor generates an electric field between the frontplane ITO and the corresponding pixel electrode. This field causes movement of a pigment within the microcapsules, which changes the color of the pixel, as observed through the ITO: when the pigments flow to the ITO side of the capsules, the color of the pigment (white in this case) determines the color of the pixel; when they ...

Silsesquioxane polymers have been successfully used as the dielectric layer in organic field‐effect transistors (FETs) deposited on robust, plastic substrates. Performance comparable to that found with silicon substrates having SiO2 as the active dielectric layer was observed with six p‐ and n‐ channel organic semiconductors. These organopolysiloxane materials can be deposited using conventional liquid coating technologies and are compatible with non‐photolithographic microcontact printing. Their low curing temperature permits the use of a variety of low‐cost plastic materials as substrates in FET devices. These findings have facilitated the realization of low‐cost, large area plastic electronics.

This study was conducted to compare women's and men's retrospective perceptions of the mentoring they received during their training and career development in chemistry. Participants were 455 graduates (135 women) who received doctoral degrees from 11 top US chemistry programs over a 5-year period (1988)(1989)(1990)(1991)(1992). In 2003, graduates completed surveys of undergraduate, graduate, post-doctoral, and initial employment experiences. In line with Social Cognitive Career Theory (Lent et al., Journal of Vocational Behavior 45: 1994), which posits that perceptions of barriers can affect career decisions, results suggest that women perceived that they received less mentoring than men at the undergraduate, graduate, and post-doctoral levels of training, likely related to gender differences in eventual career success. Possible interventions at the individual and institutional levels are discussed.

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