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Maxwell Dylla1 G. Snyder1

1, Northwestern University, Evanston, Illinois, United States

High power factors sparked significant experimental efforts to synthesize SrTiO3 with high thermoelectric efficiencies; it has become one of the most heavily studied n-type oxide thermoelectric materials. A complex band structure is believed to be responsible for the high power factors. Despite persistent efforts, the experimentally realized thermoelectric figure of merit in these materials is less than 0.5, even at temperatures as high as 1000 K. In this work, post-processed electronic structure calculations are used to elucidate how the quazi-2D electronic structure of SrTiO3 emerges from Tid-Op molecular orbitals. This chemical view offers an intuitive understanding of the complex band structure. A band model, that highlights the 2D nature of the band structure, is developed to model electronic transport in n-type SrTiO3 single crystals. This model, implemented with acoustic phonon scattering, explains the temperature and carrier dependent effective mass of SrTiO3, and the high power factors with high effective valley degeneracy. Based on this robust electronic transport model, the figure of merit at optimal doping conditions is evaluated as a function of lattice thermal conductivity, the last free parameter in the performance of SrTiO3 as a thermoelectric.

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