Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Operando direct observation of spin states correlated with device
  performance in perovskite solar cells
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph