Anisotropic thermopower on graphene thin films deposited on flexible substrates

Liquid phase exfoliation of graphene has proven successful in producing unfunctionalized samples at a near kg-a-day level [1, 2]. However, applications that truly harvest the quantum properties of graphene are yet to be implemented [3]. The work of Dresselhaus and Hicks demonstrated that low-dimensional materials display an enhanced thermopower [4]. Graphene has been used as a filler material in traditional thermoelectric nanostructured composites [5], nevertheless, it has been overlooked on its own due to its extremely high thermal and electrical conductivity in-plane. In this talk, the mild oxidation of electrochemically exfoliated graphene [6] as well as its large area results in a measurable thermopower in the out-of-plane direction will be discussed. The processing of the dispersions for film formation results in wrinkles [7] that lead to van Hove singularities in the density of states and therefore an increased thermopower [8]. At the Nanomaterials Laboratory, we have dedicated years to the research of graphene as a potential thermoelectric material and its application in the creation of flexible thermoelectric (FTE) devices. Our efforts led to the development of devices on varied substrates, including kapton and mixed fabrics, reaching Seebeck coefficients of up to 0.1 mV/K.

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[2] A. Amiri, et al, FlatChem, 8, 40-71, (2018)

[3] Nat. Phys. 20, 1 (2024)

[4] M. S. Dresselhaus, et al. Phys. Solid State, 41, 679–682 (1999)

[5] N. A. Khoso, et al, RSC Adv.,11, 16675-16687 (2021)

[6] J Rico, et al, J. Phys.: Condens. Matter 34 105701 (2022)

[7] Khaled Parvez, et al, ACS Nano 2013, 7, 4, 3598–3606 (2013)

[8] J. Canaval, E. Quintero, C. Balaguera, D. Olaya, Y. Hernandez, in preparation (2024)