Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synthesis and properties of a novel narrow band gap oligomeric
  diketopyrrolopyrrole-based organic semiconductor   An oligomeric semiconductor containing three bisthiophenediketopyrrolopyrole
units (Tri-BTDPP) was synthesized and characterized. Tri-BTDPP has a HOMO level
of -5.34 eV, a broad absorption close to the near infrared region and a low
band gap of 1.33 eV. Additionally, a promising hole mobility of 1 x 10-3 cm V-1
s-1 was achieved after thermal annealing at 150 C in organic field effect
transistors (OFET). Organic photovoltaic (OPV) cells containing Tri-BTDPP and
PC71BM as the donor/acceptor couple exhibited a power conversion efficiency
(PCE) of 0.72%. Through an intensive study of the active layer using AFM, XRD,
and DSC, it was found that Tri-BTDPP and PC71BM were unable to intermix
effectively, resulting in oversized Tri-BTDPP crystalline phases and thus poor
charge separation. Strategies to improve the OPV performance were thus
proposed.

23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol