Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Silicon clathrates for photovoltaics predicted by a two-step crystal
  structure search   Silicon in a cubic diamond structure currently plays a significant role in
the photovoltaic industry. However, the intrinsic band structures of
crystalline silicon restrict its sunlight conversion efficiency. Recently, a
clathrate-like Si-24 has been successfully synthesized, which has a
quasi-direct bandgap and sheds light on silicon-based photovoltaics. Here, we
proposed a two-step crystal structure search method based on first-principles
calculations and explored silicon clathrate structures extensively. First, the
guest-host compounds were searched at high pressure, and then, the porous
guest-free silicon clathrates were obtained by removing the guest atoms. Using
potassium as the guest atom, we identified four metastable silicon clathrate
structures, and some of them have bandgaps close to the optimal range of the
Shockley-Queisser limit and have a better absorption rate than the cubic
diamond silicon. These silicon clathrates may have promising value in
photovoltaic applications.

6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph