Saturable absorption and the changeover from saturable absorption to reverse saturable absorption of MoS<sub>2</sub> nanoflake array films

Ouyang, Qiuyun; Yu, Hailong; Zhang, Kai; Chen, Yujin

doi:10.1039/c4tc00909f

Cited by 91 publications

(69 citation statements)

References 38 publications

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“…We can observe an apparently sharp and narrow valley located at the beam focus, verifying the characteristic of reverse saturable absorption (RSA) for the composite. Very different from other reports [22,31], the WS 2 /PMMA composite presents obvious RSA instead of SA even under the lowest incident power despite (Fig. 3 (a)) the high linear absorbance at 800 nm ( Fig.…”

Section: Resultscontrasting

confidence: 75%

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Wei

Tian

Zhang

et al. 2016

Journal of Alloys and Compounds

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Section: Resultscontrasting

confidence: 75%

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Wei

Tian

Zhang

et al. 2016

Journal of Alloys and Compounds

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“…16,39,40 The total extinction coefficient a(I) can be expressed as: 16,39,40 16,39,40 The total extinction coefficient a(I) can be expressed as: 16,39,40 …”

Section: Resultsmentioning

confidence: 99%

“…Therefore the modified normalized transmittance using eqn (2) can be written as: 16,39 TðzÞ ¼ QðzÞ b 1 and b 1A can be obtained from D sa and D a , respectively, and correspondingly b 1S can also be extracted.…”

Section: Resultsmentioning

confidence: 99%

“…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][6][7][8][9] photoluminescence, 10,11 lightemitting diodes, 12 phototransistors, [13][14][15] optical limiters, 16,17 ultra fast photonic devices, 18,19 and solar cells. 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][6][7][8][9] photoluminescence, 10,11 lightemitting diodes, 12 phototransistors, [13][14][15] optical limiters, 16,17 ultra fast photonic devices, 18,19 and solar cells.…”

Section: Introductionmentioning

confidence: 99%

“…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. [16][17][18][19][27][28][29][30] Therefore, the MoS 2 -ZnO composites may have enhanced NLO properties. [16][17][18][19][27][28][29][30] Therefore, the MoS 2 -ZnO composites may have enhanced NLO properties.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear absorption, nonlinear scattering, and optical limiting properties of MoS₂–ZnO composite-based organic glasses

Ouyang

et al. 2015

Phys. Chem. Chem. Phys.

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MoS2-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 MoS2 nanosheets with an expanded spacing of the (002) plane. The MoS2-ZnO composite-based poly(methyl methacrylate) (PMMA) organic glasses (MoS2-ZnO-PMMA organic glasses) were prepared through a polymerization process. The nonlinear absorption (NLA), nonlinear scattering (NLS), and optical limiting (OL) properties of the MoS2-ZnO-PMMA organic glasses with different amounts of MoS2-ZnO were investigated using a modified Z-scan technique. Compared to MoS2-PMMA and ZnO-PMMA organic glasses, the MoS2-ZnO-PMMA organic glasses exhibited enhanced NLA, NLS, and OL properties, which were attributed to the interfacial charge transfer between MoS2 nanosheets and ZnO nanoparticles, the layered structure of MoS2 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 MoS2-ZnO-PMMA organic glasses by adjusting the input energy. The total nonlinear extinction coefficient and response time of the MoS2-ZnO-PMMA organic glasses could be up to 2380 cm GW(-1) and several hundred picoseconds, respectively. Compared to the MoS2 films, the MoS2-ZnO-PMMA organic glasses have higher optical damage threshold, better mechanical strength and flexibility. Thus the MoS2-ZnO-PMMA organic glasses are very promising for optical devices such as optical limiters, optical shutters, ultrafast lasers, and ultrafast optical switches.

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Charge Photogeneration in Few‐Layer MoS₂

Borzda

Gadermaier

Vujičić

et al. 2015

Adv Funct Materials

115

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3351wileyonlinelibrary.com for the monolayer. Hence, the monolayer, contrary to bi-and multilayers, behaves like a direct gap semiconductor and shows signifi cant fl uorescence. [ 11,12 ] The exciton binding energy for bulk MoS 2 has been determined to be 45 and 130 meV for the A and B excitons, respectively. [ 13 ] Both exciton binding energies increase upon decreasing the sample thickness, with estimates for monolayer [14][15][16] ranging from 0.4 to 0.9 eV. Despite this high exciton binding energy, monolayer MoS 2 shows a strong photovoltaic effect [ 17 ] and potential for high sensitivity photodetectors. [ 18 ] Both these functionalities require effi cient charge carrier photogeneration (CPG), either via direct excitation of mobile carriers or via exciton dissociation.The spectral signature of charge carriers has been identifi ed by absorption and fl uorescence spectroscopy of MoS 2 , where the charge concentration varies either via the gate voltage in an FET geometry [ 19 ] or via adsorption, [ 20 ] or substrate doping. [ 21 ] The absorption peaks of charges are red-shifted by about 40 meV compared with the ground-state absorption into the A and B excitons and have been attributed to optical transitions from a charged ground state to a charged exciton (trion). The possibility of alternative interpretations, such as polarons [ 22,23 ] or Stark effect in the local electric fi eld of the charges, [24][25][26] does The 2D semiconductor MoS 2 in its mono-and few-layer form is expected to have a signifi cant exciton binding energy of several 100 meV, suggesting excitons as the primary photoexcited species. Nevertheless, even single layers show a strong photovoltaic effect and work as the active material in high sensitivity photodetectors, thus indicating effi cient charge carrier photogeneration. Here, modulation spectroscopy in the sub-ps and ms time scales is used to study the photoexcitation dynamics in few-layer MoS 2 . The results suggest that the primary photoexcitations are excitons that effi ciently dissociate into charges with a characteristic time of 700 fs. Based on these fi ndings, simple suggestions for the design of effi cient MoS 2 photovoltaic and photodetector devices are made.

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Saturable absorption and the changeover from saturable absorption to reverse saturable absorption of MoS₂ nanoflake array films

Cited by 91 publications

References 38 publications

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Nonlinear absorption, nonlinear scattering, and optical limiting properties of MoS₂–ZnO composite-based organic glasses

Charge Photogeneration in Few‐Layer MoS₂

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Saturable absorption and the changeover from saturable absorption to reverse saturable absorption of MoS2 nanoflake array films

Cited by 91 publications

References 38 publications

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Facile synthesis of two-dimensional WS2 with reverse saturable absorption and nonlinear refraction properties in the PMMA matrix

Nonlinear absorption, nonlinear scattering, and optical limiting properties of MoS2–ZnO composite-based organic glasses

Charge Photogeneration in Few‐Layer MoS2

Contact Info

Product

Resources

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Saturable absorption and the changeover from saturable absorption to reverse saturable absorption of MoS₂ nanoflake array films

Nonlinear absorption, nonlinear scattering, and optical limiting properties of MoS₂–ZnO composite-based organic glasses

Charge Photogeneration in Few‐Layer MoS₂