TY - JOUR
T1 - Abrupt Thermal Shock of (NH 4 ) 2 Mo 3 S 13 Leads to Ultrafast Synthesis of Porous Ensembles of MoS 2 Nanocrystals for High Gain Photodetectors
AU - Islam, Saiful M.
AU - Sangwan, Vinod K.
AU - Li, Yuan
AU - Kang, Joohoon
AU - Zhang, Xiaomi
AU - He, Yihui
AU - Zhao, Jing
AU - Murthy, Akshay
AU - Ma, Shulan
AU - Dravid, Vinayak P.
AU - Hersam, Mark C.
AU - Kanatzidis, Mercouri G.
N1 - Funding Information:
M.S.I., M.G.K., and V.P.D. thank the National Science Foundation (NSF) Materials Research Science and Engineering Center (NSF DMR-1720139). SEM, EDS, TEM, Raman, AFM, and XPS measurements were performed at the EPIC and SPID facilities of the NUANCE Center at Northwestern University, which is partially supported by the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the Materials Research Science and Engineering Center (NSF DMR-1720139), the State of Illinois, and Northwestern University. V.K.S., J.K., and M.C.H. acknowledge the NSF 2-DARE program (NSF EFRI-1433510) for device fabrication and testing and the NSF Division of Materials Research (NSF DMR-1505849) for solution processing. Y.L., A.A.M., and V.P.D. acknowledge the NSF Division of Materials Research (DMR-1507810) for sample characterization. A.A.M. gratefully acknowledges support from the Ryan Fellowship and the International Institute for Nanotechnology at Northwestern University.
Publisher Copyright:
Copyright © 2018 American Chemical Society.
PY - 2018/11/7
Y1 - 2018/11/7
N2 - Ultrafast synthesis of high-quality transition-metal dichalcogenide nanocrystals, such as molybdenum disulfide (MoS 2 ), is technologically relevant for large-scale production of electronic and optoelectronic devices. Here, we report a rapid solid-state synthesis route for MoS 2 using the chemically homogeneous molecular precursor, (NH 4 ) 2 Mo 3 S 13 ·H 2 O, resulting in nanoparticles with estimated size down to 25 nm only in 10 s at 1000 °C. Despite the extreme nonequilibrium conditions, the resulting porous MoS 2 nanoparticles remain aggregated to preserve the form of the original rod shape bulk morphology of the molecular precursor. This ultrafast synthesis proceeds through the rapid decomposition of the precursor and rearrangement of Mo and S atoms coupled with simultaneous efficient release of massive gaseous species, to create nanoscale porosity in the resulting isomorphic pseudocrystals, which are composed of the MoS 2 nanoparticles. Despite the very rapid escape of massive amounts of NH 3 , H 2 O, H 2 S, and S gases from the (NH 4 ) 2 Mo 3 S 13 ·H 2 O mm sized crystals, they retain their original shape as they convert to MoS 2 rather than undergo explosive destruction from the rapid escape process of the gases. The obtained pseudocrystals are made of aggregated MoS 2 nanocrystals exhibit a Brunauer-Emmett-Teller surface area of ∼35 m 2 /g with an adsorption average pore width of ∼160 Å. The nanoporous MoS 2 crystals are solution processable by dispersing in ethanol and water and can be cast into large-area uniform composite films. Photodetectors fabricated from these films show more than 2 orders of magnitude higher conductivity (∼6.25 × 10 -6 S/cm) and photoconductive gain (20 mA/W) than previous reports of MoS 2 composite films. The optoelectronic properties of this nanoporous MoS 2 imply that the shallow defects that originate from the ultrafast synthesis act as sensitizing centers that increase the photocurrent gain via two-level recombination kinetics.
AB - Ultrafast synthesis of high-quality transition-metal dichalcogenide nanocrystals, such as molybdenum disulfide (MoS 2 ), is technologically relevant for large-scale production of electronic and optoelectronic devices. Here, we report a rapid solid-state synthesis route for MoS 2 using the chemically homogeneous molecular precursor, (NH 4 ) 2 Mo 3 S 13 ·H 2 O, resulting in nanoparticles with estimated size down to 25 nm only in 10 s at 1000 °C. Despite the extreme nonequilibrium conditions, the resulting porous MoS 2 nanoparticles remain aggregated to preserve the form of the original rod shape bulk morphology of the molecular precursor. This ultrafast synthesis proceeds through the rapid decomposition of the precursor and rearrangement of Mo and S atoms coupled with simultaneous efficient release of massive gaseous species, to create nanoscale porosity in the resulting isomorphic pseudocrystals, which are composed of the MoS 2 nanoparticles. Despite the very rapid escape of massive amounts of NH 3 , H 2 O, H 2 S, and S gases from the (NH 4 ) 2 Mo 3 S 13 ·H 2 O mm sized crystals, they retain their original shape as they convert to MoS 2 rather than undergo explosive destruction from the rapid escape process of the gases. The obtained pseudocrystals are made of aggregated MoS 2 nanocrystals exhibit a Brunauer-Emmett-Teller surface area of ∼35 m 2 /g with an adsorption average pore width of ∼160 Å. The nanoporous MoS 2 crystals are solution processable by dispersing in ethanol and water and can be cast into large-area uniform composite films. Photodetectors fabricated from these films show more than 2 orders of magnitude higher conductivity (∼6.25 × 10 -6 S/cm) and photoconductive gain (20 mA/W) than previous reports of MoS 2 composite films. The optoelectronic properties of this nanoporous MoS 2 imply that the shallow defects that originate from the ultrafast synthesis act as sensitizing centers that increase the photocurrent gain via two-level recombination kinetics.
KW - photodetector
KW - porous MoS nanocrystal
KW - solid-state synthesis
KW - thin films
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U2 - 10.1021/acsami.8b12406
DO - 10.1021/acsami.8b12406
M3 - Article
C2 - 30299078
AN - SCOPUS:85056210738
VL - 10
SP - 38193
EP - 38200
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 44
ER -