Using First Principles Density Functional Theory Methods to Model the Seebeck Coefficient of Bulk Silicon

LIBRARIES The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereftcrprcatcd. Abstract: Thermoelectrics are gaining significant amounts of attention considering their relevance today in the areas of sustainable energy generation and energy efficiency. In this thesis, the thermoelectric properties of bulk Silicon were modeled using ab initio density functional theory methods to determine the Si band structure. Specifically, three different models for determining the Seebeck coefficient-Parabolic Bands, Boltzmann's theory, and the 'Pudding Mold' approximation to Boltzmann's theory-were studied in depth and compared with experimental values. Here we show first principles calculations to yield Seebeck coefficients for n-type Silicon to be on the order of 300 gtV/K at-300 K, and-500 gtV/K at 300 K for the Parabolic Bands and Boltzmann approach, respectively. While the 'Pudding Mold' Theory failed in its approximations of the Seebeck coefficients, the calculations using the other two theories were found to agree closely with experimentally determined Seebeck coefficients. Acknowledgements: I would like to thank MIT, the DMSE, Professor Ceder and his group for the direction provided and the access to the necessary resources to perform the work entailed in this project. Specifically, Maria Chan was of great help and I really would not have been able to do this thesis without her guidance and feedback. Without her, this thesis would not have been.