Next Generation Thermoelectric Devices

ABSTRACT: Thermoelectric (TE) devices already found a wide range of commercial, military and aerospace applications. However, at present commercially available TE devices typically offer limited heat to electricity conversion efficiencies, well below the fundamental thermodynamic limit, calling for the development of higher efficiency materials. The team of MicroXact Inc., Virginia Tech and Sundew Technologies Inc. is proposing to develop a revolutionary high efficiency thermoelectric material fabricated on completely new fabrication principles. The material comprises the three-dimensional"wells"of PbTe/PbSe superlattices fabricated by a conformal coating via Atomic layer Deposition (ALD) of macroporous silicon substrates. Such a material will provide ZT>2 at macroscopic thicknesses of the material, permitting 20% or more conversion efficiencies for 400K-600K temperature range. In Phase I of the project the thorough model of the proposed TE material will be developed, ALD deposition of PbTe and PbSe will be developed and demonstrated on plane Si wafers and macroporous silicon pore walls. In Phase II the team will fabricate the proposed material and device, and will demonstrate ZT>2 and conversion efficiencies exceeding 20%. After the Phase II MicroXact will commercialize the technology. BENEFIT: Due to predicted unmatched performance characteristics (high efficiency, small size/weight) and large volume-compatible, economically advantageous fabrication process the proposed thermoelectric materials and devices are expected to find a wide range of defense, scientific and commercial applications. Potential DoD applications of the proposed technology are spanning from power generation (higher efficiency jet engines, additional power sources for military satellites) to efficient cooling of infrared cameras in focal plane arrays and thermoelectric cooling of electronics and optoelectronics. In all these applications the incorporation of the proposed material will result in significant improvements of operational characteristics of mentioned components. Commercial applications include auto market (where thermoelectric materials are already being used for cooling seats and improving efficiency of engine), water coolers, and potentially power plants. The advantages of the proposed technology will provide the competitive advantage to MicroXact sufficient for successful market penetration. The proposed concept, when developed and commercialized, is expected to cause a significant impact on both the DoD missions and commercial applications.