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Unprecedented Enhancement of Thermoelectric Power Factor Induced by Pressure in Small‐Molecule Organic Semiconductors
Author(s) -
Shi Wen,
Deng Tianqi,
Wu Gang,
Hippalgaonkar Kedar,
Wang JianSheng,
Yang ShuoWang
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201901956
Subject(s) - materials science , organic semiconductor , thermoelectric effect , semiconductor , thermoelectric materials , nanotechnology , seebeck coefficient , molecule , small molecule , engineering physics , optoelectronics , composite material , thermal conductivity , organic chemistry , thermodynamics , genetics , biology , engineering , chemistry , physics
Establishing the relationship between pressure and heat–electricity interconversion in van der Waals bonded small‐molecule organic semiconductors is critical not only in designing flexible thermoelectric materials, but also in developing organic electronics. Here, based on first‐principles calculations and using naphthalene as a case study, an unprecedented elevation of p‐type thermoelectric power factor induced by pressure is demonstrated; and the power factor increases by 267% from 159.5 µW m −1 K −2 under ambient conditions to 585.8 µW m −1 K −2 at 2.1 GPa. The underlying mechanism is attributed to the dramatic inhibition of lattice‐vibration‐caused electronic scattering. Furthermore, it is revealed that both restraining low‐frequency intermolecular vibrational modes and increasing intermolecular electronic coupling are two essential factors that effectively suppress the electron–phonon scattering. From the standpoint of molecular design, these two conditions can be achieved by extending the π‐conjugated backbones, introducing long alkyl sidechains to the π‐cores, and substituting heteroatoms in the π‐cores.