Title: Ab initio optimization of phonon drag effect for lower-temperature thermoelectric energy conversion

Abstract

Although the thermoelectric figure of merit zT above 300 K has seen significant improvement recently, the progress at lower temperatures has been slow, mainly limited by the relatively low Seebeck coefficient and high thermal conductivity. We report, for the first time to our knowledge, success in first-principles computation of the phonon drag effect—a coupling phenomenon between electrons and nonequilibrium phonons—in heavily doped region and its optimization to enhance the Seebeck coefficient while reducing the phonon thermal conductivity by nanostructuring. Our simulation quantitatively identifies the major phonons contributing to the phonon drag, which are spectrally distinct from those carrying heat, and further reveals that although the phonon drag is reduced in heavily doped samples, a significant contribution to Seebeck coefficient still exists. An ideal phonon filter is proposed to enhance zT of silicon at room temperature by a factor of 20 to ~0.25, and the enhancement can reach 70 times at 100 K. This work opens up a new venue toward better thermoelectrics by harnessing nonequilibrium phonons.

Authors:

Zhou, Jiawei ^[1]; Liao, Bolin ^[1]; Qiu, Bo ^[1]; Huberman, Samuel ^[1]; Esfarjani, Keivan ^[2]; Dresselhaus, Mildred S. ^[3]; Chen, Gang ^[1]

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+ Show Author Affiliations

1. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139,
2. Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, NJ 08854,, Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854,
3. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139,, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139

Publication Date:

Mon Nov 16 00:00:00 EST 2015

Research Org.:

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1235174

Alternate Identifier(s):

OSTI ID: 1370969

Grant/Contract Number:  

SC0001299/DE-FG02-09ER46577; SC0001299; FG02-09ER46577

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 112 Journal Issue: 48; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING; phonon drag; nonequilibrium phonon; electron phonon interaction; thermoelectrics; nanocluster scattering