Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Flexible perovskite/Cu(In,Ga)Se2 monolithic tandem solar cells   We report a proof-of-concept two-terminal perovskite/Cu(In, Ga)Se2 (CIGS)
monolithic thin-film tandem solar cell grown on ultra-thin (30-microns thick),
light-weight, and flexible polyimide foil with a steady-state power conversion
efficiency of 13.2% and a high open-circuit voltage over 1.75 V under standard
test condition.

24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat