摘要
Understanding how to optimize electronic band structures for thermoelectrics is a topic of long-standing interest in the community.Prior models have been limited to simplified bands and/or scattering models.In this study,we apply more rigorous scattering treatments to more realistic model band structures—upward-parabolic bands that inflect to an inverted-parabolic behavior—including cases of multiple bands.In contrast to common descriptors(e.g.,quality factor and complexity factor),the degree to which multiple pockets improve thermoelectric performance is bounded by interband scattering and the relative shapes of the bands.We establish that extremely anisotropic“flat-and-dispersive”bands,although best-performing in theory,may not represent a promising design strategy in practice.Critically,we determine optimum bandwidth,dependent on temperature and lattice thermal conductivity,from perfect transport cutoffs that can in theory significantly boost zT beyond the values attainable through intrinsic band structures alone.Our analysis should be widely useful as the thermoelectric research community eyes zT>3.
基金
This work was led by funding from U.S.Department of Energy,Office of Basic Energy Sciences,Early Career Research Program,which supported J.P.and A.J.Lawrence Berkeley National Laboratory is funded by the Department of Energy under award DE-AC02-05CH11231
V.O.acknowledges financial support from the National Science Foundation Grant DMR-1611507.This work used resources of the National Energy Research Scientific Computing Center,a Depatment of Energy Office of Science User Facility supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231
J.P.thanks Younghak Kwon of UCLA Mathematics for helpful discussions.
