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Water Based Process for Fabricating Thermoelectric Materials





Berkeley Lab scientists Rachel Segalman, Jeffrey Urban and Kevin See have invented a water based process to make thermoelectric films. The resulting composite film displays both the high thermovoltage expected of nanocrystals and the high electrical conductivity of polymers—a beneficial pairing of traits. These traits can counteract in conventional thermoelectric materials to limit a thermoelectric device’s efficiency and economic utility.

In the Berkeley Lab technology, water soluble tellurium nanorods coated with a conductive polymer are spin- or drop-cast into high quality, smooth films. The resulting composite is a thin film thermoelectric device with a figure of merit (ZT) of 0.2—ten times the efficiency achieved by competing groups that employ carbon nanotubes and organic polymers. With further engineering, using the same materials and techniques, a five-fold improvement in efficiency (a ZT of 1.0) is attainable.

Significant reductions in cost are made possible by the use of low-temperature solution processing similar to that employed in the production of plastic photovoltaic and light-emitting devices. This readily scalable fabrication process can be carried out using only water as a solvent. In the aqueous solution is a mixture of inorganic tellurium and commercially available poly(3,4-ethylenedioxythiophene poly(styrenesulfonate) or PEDOT:PSS, a conducting polymer. The rod-shaped tellurium nanocrystals, coated with that polymer, are formed in the casting process.

Thermoelectric devices hold enormous potential for converting waste heat into electricity or for heating and cooling without the use of mechanical pumps or fans. Such devices can convert heat into electric power or be configured into solid state heat pumps that cool or emit heat depending on the direction an electric current is flowing. The barriers to widespread use of thermoelectric devices have been their relatively high cost and low efficiency. The Berkeley Lab technology charts a path toward lower cost and higher efficiency.

DEVELOPMENT STAGE: Bench scale prototype. 

STATUS: Published patent application WO2011149991 available at  Available for licensing or collaborative research.


See, K., Feser, J., Chen, C.E., Majumdar, A., Urban, J., Segalman, R. “Water Processable Polymer-Nanocrystal Hybrids for Thermoelectrics,” Nano Lett., Oct. 5, 2010.

Risbud, Aditi. “Berkeley Lab Scientists Generate Low-Cost Hybrid Thermoelectrics,” Berkeley Lab News Center, Nov., 5, 2010.


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