11:48 a.m., April 30, 2009----Joshua Zide, assistant professor in the Department of Materials Science and Engineering at the University of Delaware, has been selected to receive a prestigious Young Investigator award from the Office of Naval Research (ONR) to develop new semiconductors and nanocomposites for thermoelectric power generation and other applications. The three-year $510,000 grant is one of just 15 awarded nationwide.

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Zide's research will focus on incorporating bismuth into compound semiconductors, an achievement that has been reported in only three labs throughout the world and none in the U.S. His work expands these bismide materials onto different substrates from previous efforts.

“Dilute bismides are a new, virtually unexplored, and extremely promising material system for thermoelectric power generation,” Zide says. “They offer the potential for significant reduction in thermal conductivity and improvements in electronic properties over other semiconductors in this class, enabling high-efficiency thermoelectric materials.”

Thermoelectric devices create a voltage when there is a different temperature on each side. Conversely, application of a voltage to such a device creates a temperature difference. This effect can be used to generate electricity, as well as to heat or cool objects. “Thermoelectric conversion is analogous to the work done by a solar cell, but it uses heat rather than light,” Zide explains. One potential application is in hybrid cars, where excess heat could be converted to energy.

For now, however, Zide is interested in the basic science, and he knows there will be challenges in growing the material. “We're looking at fundamentally new growth conditions, and we can only guess at the properties that will be achievable,” he says.

But his best guess is that the new materials will offer exceptional efficiency. He explains that while the thermoelectric figure of merit (known as ZT) of current commercial materials is approximately 1, and state-of-the-art materials have a ZT ranging from 1.5 - 2.4, the proposed materials offer the potential for a ZT of 2.5 - 3.

“Thermoelectric power generation is highly relevant to ONR's mission and goals,” Zide says. “For several naval customers, waste heat recovery is extraordinarily important, and efficient thermoelectric power generation is an attractive technology, especially in applications where robust, solid-state technologies offer a reliable alternative to existing technologies.”

In addition to these new dilute bismide semiconductors, Zide will explore the creation of a novel and promising class of metal-semiconductor nanocomposites based on these materials. Such nanocomposites offer advantages for certain optical and electronic properties over those of bulk materials.

Zide, who earned his Ph.D. in materials science at the University of California Santa Barbara, joined the UD faculty in September 2007.

Article by Diane Kukich
Photo by Ambre Alexander