Available Technology

Composites of Doped Semiconducting Single-walled Carbon Nanotubes and Fluorene-based Polymers for Thermoelectric Power Conversion

Thermoelectric materials are materials which are able to create electricity when exposed to a heat source. This phenomenon is caused by the flow of electrons from heated regions of the material to cooler regions, known as the Seebeck effect. While the voltage induced by the Seebeck effect is fairly small - on the order of microvolts per degree Kelvin – due to the prevalence of heat as a waste byproduct of other processes, thermoelectric materials have found a foothold in a number of promising applications. These uses include harnessing automotive exhaust for power, powering wireless or portable devices, power-generating clothing, and industrial waste heat recycling. While thermoelectrics show great promise for the above applications, they currently are generally too expensive (on a $/watt basis) for the amount of electricity generated. As noted above, thermoelectric materials are evaluated by use of a figure of merit known as the Seebeck coefficient. Simply stated, the Seebeck coefficient is the ratio of energy produced compared to a given temperature gradient of a material. Typical Seebeck coefficients are currently below 2 µV/°K, but there is no material property that creates this limit – values could theoretically be much higher. As the Seebeck coefficient for a material increases, more electricity can be created under the same temperature gradient – leading to more cost-effective thermoelectrics. This would also allow for thermoelectrics to be used across more applications, at lower cost.
In this case, the Seebeck coefficient for these single-walled carbon nanotube (“SWCNT”) materials range from 200 µV/°K – 2.5 mV/°K – an improvement of several orders of magnitude over previous recorded values. These Seebeck coefficients show that the amount of energy generated from a heat source could increase 100-1000x over comparable thermoelectric materials. In addition to the efficiency increase, SWCNT materials are low-cost, lightweight, and flexible, allowing optimization of the material for uses in which typical ceramic thermoelectric materials are either too heavy, too rigid, or too expensive. This is a game-changing improvement in the world of thermoelectrics, with the potential to open the doors to new applications of thermoelectric materials and further improving the cost-effectiveness of current thermoelectric applications.
Several orders of magnitude of improvement in the Seebeck coefficient -100 to 1000x more energy generated from a heat source than comparable thermoelectric materials -Low cost -Lightweight -Flexible
Internal Laboratory Ref #: 
NREL ROI 14-90
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