Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling thermoelectric performance in nanoporous nanocrystalline
  silicon   Introducing hierarchical disorder from multiple defects into materials
through nanostructuring is one of the most promising directions to achieve
extremely low thermal conductivities and thus improve thermoelectric
performance. The success of nanostructuring relies on charge carriers having
shorter mean-free-paths than phonons so that the latter can be selectively
scattered. Nevertheless, introducing disorder into a material often comes at
the expense of scattering charge carriers as well as phonons. In order to
determine the tradeoff between the degradation of the lattice thermal
conductivity and of the power factor due to this, we perform a theoretical
investigation of both phonon and electron transport in nanocrystalline,
nanoporous Si geometries. We use molecular dynamics for phonon transport
calculations and the non-equilibrium Green's function method for electronic
transport. We report on the engineering tradeoff that the porosity (number of
pores and their in-between distance) has on the overall thermoelectric
performance for the material optimization. We indeed find that the reduction in
thermal conductivity is stronger compared to the reduction in the power factor,
for the low porosities considered in this study (up to 5 %), and that the ZT
figure of merit can experience a large increase, especially when grain
boundaries are included, compared to just nanoporosity.

16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph