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In this Letter, we present a novel strategy to control the thermoelectric properties of individual PbSe nanowires. Using a field-effect gated device, we were able to tune the Seebeck coefficient of single PbSe nanowires from 64 to 193 microV x K(-1). This direct electrical field control of sigma and S suggests a powerful strategy for optimizing ZT in thermoelectric devices. These results represent the first demonstration of field-effect modulation of the thermoelectric figure of merit in a single semiconductor nanowire. This novel strategy for thermoelectric property modulation could prove especially important in optimizing the thermoelectric properties of semiconductors where reproducible doping is difficult to achieve.

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The thermoelectric properties of individual solution-phase synthesized p-type PbSe nanowires have been examined. The nanowires showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing of the PbSe nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration or hole mobility. After optimal annealing, single PbSe nanowires exhibited a thermoelectric fi gure of merit (ZT) of 0.12 at room temperature.Solid state thermoelectric devices can convert thermal gradients into electrical power and have attracted increased interest for energy applications [1]. High performance, reliability, portability, and low cost are among the key characteristics that make these solid state devices attractive for practical applications. Efficient thermal to electrical power conversion requires low thermal conductivity to sustain a good temperature gradient and high charge carrier mobility to generate electrical power. The device performance is characterized by the thermoelectric figure of merit, ZT = S 2 T , where S is the thermopower (Seebeck coeffi cient), is the electrical conductivity, T is the absolute temperature, and is the thermal conductivity from both lattice and charge carrier contributions. For a solid state thermoelectric module to compete on the commercial market, a value of ZT of three or greater is considered necessary. Due to the interrelated nature of S, , and traditional bulk materials have not achieved a value of ZT greater than unity [2]. Recently, theoretical predictions [3,4] and experimental measurements [5 11] indicated that Nano Research Nano Research