6036 | Phys. Chem. Chem. Phys., 2015, 17, 6036--6043 This journal is
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the Owner Societies 2015
Cite this: Phys. Chem. Chem. Phys.,
2015, 17,6036
Nonlinear absorption, nonlinear scattering, and
optical limiting properties of MoS
2
–ZnO
composite-based organic glasses†
Bin Qu,
ab
Qiuyun Ouyang,*
a
Xianbo Yu,
a
Wenhe Luo,
a
Lihong Qi
a
and Yujin Chen*
a
MoS
2
–ZnO composites were synthesized using a solution-based method. The scanning electron
microscopy and transmission electron microscopy analysis demonstrated that ZnO nanoparticles with a
size of about 4.5 nm were coated on the basal surface of MoS
2
nanosheets with an expanded spacing
of the (002) plane. The MoS
2
–ZnO composite-based poly(methyl methacrylate) (PMMA) organic glasses
(MoS
2
–ZnO–PMMA organic glasses) were prepared through a polymerization process. The nonlinear
absorption (NLA), nonlinear scattering (NLS), and optical limiting (OL) properties of the MoS
2
–ZnO–PMMA
organic glasses with different amounts of MoS
2
–ZnO were investigated using a modified Z-scan technique.
Compared to MoS
2
–PMMA and ZnO–PMMA organic glasses, the MoS
2
–ZnO–PMMA organic glasses
exhibited enhanced NLA, NLS, and OL properties, which were attributed to the interfacial charge transfer
between MoS
2
nanosheets and ZnO nanoparticles, the layered structure of MoS
2
nanosheets, the small size
effect of ZnO nanoparticles, and the local field effect. In addition, a changeover from saturable absorption
(SA) to reverse saturable absorption (RSA) could be realized in the MoS
2
–ZnO–PMMA organic glasses
by adjusting the input energy. The total nonlinear extinction coefficient and response time of the MoS
2
–
ZnO–PMMA organic glasses could be up to 2380 cm GW
1
and several hundred picoseconds, respectively.
Compared to the MoS
2
films, the MoS
2
–ZnO–PMMA organic glasses have higher optical damage threshold,
better mechanical strength and flexibility. Thus the MoS
2
–ZnO–PMMA organic glasses are very promising
for optical devices such as optical limiters, optical shutters, ultrafast lasers, and ultrafast optical switches.
1 Introduction
Molybdenum disulfide (MoS
2
) is a typical two-dimensional (2D)
layered material, in which hexagonal layers of Mo atoms are
sandwiched between two layers of sulfur atoms (S).
1,2
Due to
its unique layered structure and relatively narrow band gap
(1.2–1.9 eV),
3,4
MoS
2
has potential applications in optoelectronic
fields such as photocatalysis,
5–9
photoluminescence,
10,11
light-
emitting diodes,
12
phototransistors,
13–15
optical limiters,
16,17
ultra fast photonic devices,
18,19
and solar cells.
20
However, for
the single MoS
2
material, the intrinsic defects such as disloca-
tions, stacking fault, the high recombination rate of the photo-
generated electron–hole pairs, and the lack of effective emission
sites
6,21
limit its practical applications in some fields. Recently, it
has been reported that by combining MoS
2
with other materials,
these drawbacks can be overcome to some degree.
22–26
For
example, combining MoS
2
with graphene, ZnO, TiO
2
, and CdS
can enhance photocatalytic activities,
6–9
nonlinear optical (NLO)
properties,
17
and electrochemical performances, respectively.
22
MoS
2
–carbon hybrid possesses a highly efficient platinum-free
counter electrode for dye-sensitized solar cells.
23
MoS
2
was
blended with single-walled carbon nanotubes (SWNTs) to form
novel composite thin films, which show strong electrochemical
performance for lithium ion batteries.
24
Recently, MoS
2
@ZnO
nanoheterojunctions were fabricated and exhibited enhanced
field emission properties.
6
However, to date the NLO properties
of the MoS
2
–ZnO composite-based organic glasses have not been
reported.
ZnO, as a wide semiconductor with a band gap of 3.37 eV
and a high exciton binding energy of 60 meV, has been widely
used as a photocatalyst,
6
and in optical shutters,
27,28
optical
limitters,
29
heterojunction laser diodes, and UV lasers.
30
Due to
its wide band gap structure, ZnO has been combined with
graphene
28
or other semiconductors with narrower band
gaps, including Cu
2
S,
31
Cu
2
O,
32
CdS,
33
CdSe,
34
etc., to enhance
optoelectronic performances. In addition, it has been proved
a
Key Laboratory of In-Fiber Integrated Optics of Ministry of Education,
College of Science, Harbin Engineering University, Harbin 150001, China.
E-mail: chenyu jin@hrbeu.edu.cn, qyouyang7823@aliyun.com
b
Department of Applied Chemistry, College of Science,
Northeast Agricultural University, Harbin 150030, China
† Electronic supplementary information (ESI) available: Comparison of the high-
magnification TEM images of MoS
2
between MoS
2
–ZnO. See DOI: 10.1039/
c4cp05227g
Received 11th November 2014,
Accepted 22nd January 2015
DOI: 10.1039/c4cp05227g
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