Chalcogenide Nanosheets: Optical Signatures of Many-Body Effects and Electronic Band Structure

  • Ivan Verzhbitskiy
  • Goki Eda
Part of the Nanostructure Science and Technology book series (NST)


Layered chalcogenide materials exhibit a wide range of physical properties associated with their quasi-2D nature and have been studied extensively since the second half of the twentieth century. Following the discovery of graphene, the ability to isolate individual monolayer of these material has recently opened up numerous avenues for probing various physical effects in the ultimate 2D confinement limit. Monolayers of group 6 transition metal dichalcogenides are an attractive platform for studying many-body effects, non-linear optics, and valley physics. Along with other emerging 2D chalcogenides, they offer unique opportunities for realizing novel devices and their technological implementations. Here we review the fundamental properties of various semiconducting chalcogenide nanosheets and their heterostructures with emphasis on the electronic structure and optical properties of Mo- and W-based dichalcogenides (MoS2, MoSe2, MoTe2, WS2, WSe2). We discuss the current understanding on the the layer-dependent energy dispersion and and its optical signatures in these material systems. We further discuss the strong excitonic effects and review recent experimental efforts in estimating exciton binding energy using various optical and opto-electrical approaches.


Density Functional Theory Calculation Exciton Binding Energy Conduction Band Minimum Monolayer MoS2 Scanning Tunneling Spectroscopy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.







Two-photon photoluminescence excitation


Annular dark field


Atomic layer deposition


Angle-resolved photoemission spectroscopy


Bilayer graphene


Conduction band minimum


Charge density wave




Chemical vapor deposition


Chemical vapor transport


Density functional theory


Density of state


Differential reflectance


Highly oriented pyrolytic graphite


Joint density of states


Molecular beam epitaxy


Metal atoms (M) and chalcogen atoms (X)








Photoluminescence excitation spectroscopy


Second harmonic generation spectroscopy


Scanning transmission electron microscopy


Scanning tunneling microscopy


Scanning tunneling spectroscopy


Transient absorption


Transition metal dichalcogenide


Valence band maximum


X-ray photoelectron spectroscopy


  1. 1.
    Wilson AD, Yoffe JA (1969) The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties. Adv Phys 18:193–335CrossRefGoogle Scholar
  2. 2.
    Murray RB, Bromley RA, Yoffe AD (1972) The band structures of some transition metal dichalcogenides. II. Group IVA; octahedral coordination. J Phys C Sol Stat Phys 5:746Google Scholar
  3. 3.
    Bromley RA, Murray RB, Yoffe AD (1972) The band structures of some transition metal dichalcogenides. III. Group VIA: trigonal prism materials. J Phys C Sol Stat Phys 5:759Google Scholar
  4. 4.
    Liang WY (1973) Optical anisotropy in layer compounds. J Phys C Solid Stat Phys 6:551–565CrossRefGoogle Scholar
  5. 5.
    Lévy F (1979) Physics and chemistry of materials with layered structures: intercalated layered materials. Reidel, DordrechtCrossRefGoogle Scholar
  6. 6.
    Somoano RB, Hadek V, Rembaum A (1973) Alkali metal intercalates of molybdenum disulfide. J Chem Phys 58:697CrossRefGoogle Scholar
  7. 7.
    Woollam JA, Somoano RB (1976) Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2. Phys Rev B 13:3843CrossRefGoogle Scholar
  8. 8.
    Hasan MZ, Kane CL (2010) Topological insulators. Rev Mod Phys 82:3045CrossRefGoogle Scholar
  9. 9.
    Butler SZ et al (2013) Progress, challenges, and opportunities in two-dimensional materials beyond graphene. ACS Nano 7:2898–2926CrossRefGoogle Scholar
  10. 10.
    Kasowski RV (1973) Band structure of MoS2 and NbS2. Phys Rev Lett 30:1175Google Scholar
  11. 11.
    Lebègue S, Eriksson O (2009) Electronic structure of two-dimensional crystals from ab initio theory. Phys Rev B 79:115409Google Scholar
  12. 12.
    Hu KH et al (2009) Tribological properties of molybdenum disulfide nanosheets by monolayer restacking process as additive in liquid paraffin. Tribol Int 42:33–39CrossRefGoogle Scholar
  13. 13.
    Lipatov A et al (2015) Few-layered titanium trisulfide (TiS3) field-effect transistors. Nanoscale 7:12291–12296CrossRefGoogle Scholar
  14. 14.
    Zolyomi V, Drummond ND, Fal’ko VI (2003) Band structure and optical transitions in atomic layers of hexagonal gallium chalcogenides. Phys Rev B 87:195403Google Scholar
  15. 15.
    Malone BD, Kaxiras E (2013) Quasiparticle band structures and interface physics of SnS and GeS. Phys Rev B 87:245312CrossRefGoogle Scholar
  16. 16.
    Buscema M et al (2015) Photocurrent generation with two-dimensional van der Waals semiconductors. Chem Soc Rev 44:3691–3718CrossRefGoogle Scholar
  17. 17.
    Gomes LC, Carvalho A (2015) Phosphorene analogues: isoelectronic two-dimensional group-IV monochalcogenides with orthorhombic structure. Phys Rev B 92:085406CrossRefGoogle Scholar
  18. 18.
    Consadori F, Frindt RF (1970) Crystal size effects on the exciton absorption spectrum of WSe2. Phys Rev B 2:4893–4896CrossRefGoogle Scholar
  19. 19.
    Novoselov KS et al (2005) Electric field effect in atomically thin carbon films. Science 306:666CrossRefGoogle Scholar
  20. 20.
    Chhowalla M et al (2013) The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nat Chem 5:263–275CrossRefGoogle Scholar
  21. 21.
    Wang QH et al (2012) Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nat Nanotechnol 7:699–712CrossRefGoogle Scholar
  22. 22.
    Bhimanapati GR et al (2015) Recent advances in two-dimensional materials beyond graphene. ACS Nano 9:11509–11539CrossRefGoogle Scholar
  23. 23.
    Gupta A, Sakthivel T, Seal S (2015) Recent development in 2D materials beyond graphene. Prog Mat Sci 73:44–126CrossRefGoogle Scholar
  24. 24.
    Splendiani A et al (2010) Emerging photoluminescence in monolayer MoS2. Nano Lett 10:1271–1275CrossRefGoogle Scholar
  25. 25.
    Mak KF et al (2010) Atomically thin MoS2: a new direct-gap semiconductor. Phys Rev Lett 105:136805CrossRefGoogle Scholar
  26. 26.
    Zeng H et al (2012) Valley polarization in MoS2 monolayers by optical pumping. Nat Nanotechnol 7:490–493CrossRefGoogle Scholar
  27. 27.
    Mak KF et al (ed) (2012) Control of valley polarization in monolayer MoS2 by optical helicity. Nat Nanotechnol 7:494–498Google Scholar
  28. 28.
    Malard AM et al (2013) Observation of intense second harmonic generation from MoS2 atomic crystals. Phys Rev B 87:201401Google Scholar
  29. 29.
    Li Y et al (2013) Probing symmetry properties of few-layer MoS2 and h-BN by optical second-harmonic generation. Nano Lett 13:3329–3333Google Scholar
  30. 30.
    Kumar N et al (2013) Second harmonic microscopy of monolayer MoS2. Phys Rev B 87:161403Google Scholar
  31. 31.
    Wu W et al (2014) Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics. Nature 514:470–474CrossRefGoogle Scholar
  32. 32.
    Zhu H et al (2015) Observation of piezoelectricity in free-standing monolayer MoS2. Nat Nanotechnol 10:151–155CrossRefGoogle Scholar
  33. 33.
    Zhang C et al (2014) Direct imaging of band profile in single layer MoS2 on graphite: quasiparticle energy gap, metallic edge states and edge band bending. Nano Lett 14:2443–2447CrossRefGoogle Scholar
  34. 34.
    Chernikov A et al (2014) Exciton binding energy and nonhydrogenic rydberg series in monolayer WS2. Phys Rev Lett 113:076802CrossRefGoogle Scholar
  35. 35.
    Ye Z et al (2014) Probing excitonic dark states in single-layer tungsten disulphide. Nature 513:214–218CrossRefGoogle Scholar
  36. 36.
    Ye JT et al (2012) Superconducting dome in a gate-tuned band insulator. Science 30:1193–1196CrossRefGoogle Scholar
  37. 37.
    Geim AK, Grigorieva IV (2013) Van der Waals heterostructures. Nature 499:419–425CrossRefGoogle Scholar
  38. 38.
    Lee JU et al (2016) Raman signatures of polytypism in molybdenum disulfide. ACS Nano 10:1948–1953CrossRefGoogle Scholar
  39. 39.
    Brown BE (1966) The crystal structures of WTe2 and high-temperature MoTe2. Acta Cryst 20:268–274CrossRefGoogle Scholar
  40. 40.
    Vellinga MB, Jonge R, Haas C (1970) Semiconductor to metal transition in MoTe2. J Solid Stat Chem 2:299–302CrossRefGoogle Scholar
  41. 41.
    Coehoorn R, Haas C, de Groot RA (1987) Electronic structure of MoSe2, MoS2, and WSe2. II. The nature of the optical band gaps. Phys Rev B 35:6203–6206CrossRefGoogle Scholar
  42. 42.
    Novoselov KS et al (2005) Two-dimensional atomic crystals. PNAS 102:10451CrossRefGoogle Scholar
  43. 43.
    Schafer H (1964) Chemical transport reactions. Academic Press, New YorkGoogle Scholar
  44. 44.
    Koma A, Sunouchi K, Miyajima T (1984) Fabrication and characterization of heterostructures with subnanometer thickness. Microelectron Eng 2:129–136CrossRefGoogle Scholar
  45. 45.
    Zheng J et al (2014) High yield exfoliation of two-dimensional chalcogenides using sodium naphthalenide. Nature Commun 5:2995Google Scholar
  46. 46.
    Nicolosi V et al (2013) Liquid exfoliation of layered materials. Science 340:6139CrossRefGoogle Scholar
  47. 47.
    Amara KK et al (2014) Wet chemical thinning of molybdenum disulfide down to its monolayer. APL Mater 2:092509CrossRefGoogle Scholar
  48. 48.
    Huang Y et al (2013) An innovative way of etching MoS2: characterization and mechanistic investigation. Nano Res 6:200CrossRefGoogle Scholar
  49. 49.
    Liu Y et al (2013) Layer-by-layer thinning of MoS2 by plasma. ACS Nano 7:4202CrossRefGoogle Scholar
  50. 50.
    Castellanos-Gomez A et al (2012) Laser-thinning of MoS2: on demand generation of a single-layer semiconductor. Nano Lett 12:3187CrossRefGoogle Scholar
  51. 51.
    Altavilla C, Sarno M, Ciambelli P (2011) A novel wet chemistry approach for the synthesis of hybrid 2D free-floating single or multilayer nanosheets of MS2@oleylamine (M=Mo, W). Chem Mater 23:3879CrossRefGoogle Scholar
  52. 52.
    Tan LK et al (2014) Atomic layer deposition of a MoS2 film. Nanoscale 6:10584CrossRefGoogle Scholar
  53. 53.
    Zhan Y et al (2012) Large-area vapor-phase growth and characterization of MoS2 atomic layers on a SiO2 substrate. Small 8:966CrossRefGoogle Scholar
  54. 54.
    Liu K-K et al (2012) Growth of large-area and highly crystalline MoS2 thin layers on insulating substrates. Nano Lett 12:1538CrossRefGoogle Scholar
  55. 55.
    Lee Y-H et al (2012) Synthesis of large-area MoS2 atomic layers with chemical vapor deposition. Adv Mater 24:2320CrossRefGoogle Scholar
  56. 56.
    Amani M et al (2013) Electrical performance of monolayer MoS2 field-effect transistors prepared by chemical vapor deposition. Appl Phys Lett 102:193107CrossRefGoogle Scholar
  57. 57.
    van der Zande AM et al (2013) Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide. Nat Mater 12:554CrossRefGoogle Scholar
  58. 58.
    Wang H et al (2012) Integrated circuits based on bilayer MoS2 transistors. Nano Lett 12:4674CrossRefGoogle Scholar
  59. 59.
    Najmaei S et al (2013) Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers. Nat Mater 12:754CrossRefGoogle Scholar
  60. 60.
    Yu Y et al (2013) Controlled scalable synthesis of uniform, high-quality monolayer and few-layer MoS2 films. Sci Rep 3:1866Google Scholar
  61. 61.
    Gong C et al (2013) Metal contacts on physical vapor deposited monolayer MoS2. ACS Nano 7:11350CrossRefGoogle Scholar
  62. 62.
    Liu Y et al (2014) Mesoscale imperfections in MoS2 atomic layers grown by a vapor transport technique. Nano Lett 14:4682CrossRefGoogle Scholar
  63. 63.
    Liu H et al (2013) Statistical study of deep submicron dual-gated field-effect transistors on monolayer chemical vapor deposition molybdenum disulfide films. Nano Lett 13:2640CrossRefGoogle Scholar
  64. 64.
    Liu B et al (2014) High-performance chemical sensing using schottky-contacted chemical vapor deposition grown monolayer MoS2 transistors. ACS Nano 8:5304CrossRefGoogle Scholar
  65. 65.
    Najmaei S et al (2014) Electrical transport properties of polycrystalline monolayer molybdenum disulfide. ACS Nano 8:7930CrossRefGoogle Scholar
  66. 66.
    Schmidt H et al (2014) Transport properties of monolayer MoS2 grown by chemical vapor deposition. Nano Lett 14:1909CrossRefGoogle Scholar
  67. 67.
    Dumcenco D et al (2015) Large-area epitaxial monolayer MoS2. ACS Nano 9:4611–4620CrossRefGoogle Scholar
  68. 68.
    Zhu W et al (2014) Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition. Nat Commun 5:3087Google Scholar
  69. 69.
    Wang X et al (2014) Chemical vapor deposition growth of crystalline monolayer MoSe2. ACS Nano 8:5125CrossRefGoogle Scholar
  70. 70.
    Shaw JC et al (2014) Chemical vapor deposition growth of monolayer MoSe2 and nanosheets. Nano Res 7:1CrossRefGoogle Scholar
  71. 71.
    Zhang Y et al (2013) Controlled growth of high-quality monolayer WS2 layers on sapphire and imaging its grain boundary. ACS Nano 7:8963CrossRefGoogle Scholar
  72. 72.
    Sirlina T et al (2000) Study on preparation, growth mechanism, and optoelectronic properties of highly oriented WSe2 thin films. J Mater Res 15:2636Google Scholar
  73. 73.
    Huang J-K et al (2014) Large-area synthesis of highly crystalline WSe2 monolayers and device applications. ACS Nano 8:923CrossRefGoogle Scholar
  74. 74.
    Gong Y et al (2014) Band gap engineering and layer-by-layer mapping of selenium-doped molybdenum disulfide. Nano Lett 14:442CrossRefGoogle Scholar
  75. 75.
    Lin Y-C et al (2014) Properties of individual dopant atoms in single-layer MoS2: atomic structure, migration, and enhanced reactivity. Adv Mater 26:2857CrossRefGoogle Scholar
  76. 76.
    Hong J et al (2015) Exploring atomic defects in molybdenum disulphide monolayers. Nat Commun 6:6293CrossRefGoogle Scholar
  77. 77.
    Zhou W et al (2013) Intrinsic structural defects in monolayer molybdenum disulfide. Nano Lett 13:2615CrossRefGoogle Scholar
  78. 78.
    Lu C-P et al (2014) Bandgap, mid-gap states, and gating effects in MoS2. Nano Lett 14:4628CrossRefGoogle Scholar
  79. 79.
    Tongay S et al (2013) Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons. Sci Rep 3:2657CrossRefGoogle Scholar
  80. 80.
    Radisavljevic B et al (2011) Single-layer MoS2 transistors. Nat Nanotechnol 6:147CrossRefGoogle Scholar
  81. 81.
    Kim S et al (2012) High-mobility and low-power thin-film transistors based on multilayer MoS2 crystals. Nat Commun 3:1011CrossRefGoogle Scholar
  82. 82.
    Baugher BWH et al (2013) Intrinsic electronic transport properties of high-quality monolayer and bilayer MoS2. Nano Lett 13:4212CrossRefGoogle Scholar
  83. 83.
    Wang Z et al (2013) Hopping transport through defect-induced localized states in molybdenum disulphide. Nat Commun 4:2642Google Scholar
  84. 84.
    Yu Z et al (2014) Towards intrinsic charge transport in monolayer molybdenum disulfide by defect and interface engineering. Nat Commun 5:5290CrossRefGoogle Scholar
  85. 85.
    Liu G-B et al (2015) Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides. Chem Soc Rev 44:2643–2663CrossRefGoogle Scholar
  86. 86.
    Zhao W et al (2013) Evolution of electronic structure in atomically thin sheets of WS2 and WSe2. ACS Nano 7:791–797Google Scholar
  87. 87.
    Tongay S et al (2012) Thermally driven crossover from indirect toward direct bandgap in 2D semiconductors: MoSe2 versus MoS2. Nano Lett 12:5576–5580CrossRefGoogle Scholar
  88. 88.
    Zhang Y et al (2014) Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2. Nat Nanotechnol 9:111–115CrossRefGoogle Scholar
  89. 89.
    Jin W et al (2013) Direct measurement of the thickness-dependent electronic band structure of MoS2 using angle-resolved photoemission spectroscopy. Phys Rev Lett 111:106801CrossRefGoogle Scholar
  90. 90.
    Zeng H et al (2013) Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides. Sci Rep 3:1608Google Scholar
  91. 91.
    Zhang C et al (2015) Probing critical point energies of transition metal dichalcogenides: surprising indirect gap of single layer WSe2. Nano Lett 15:6494–6500CrossRefGoogle Scholar
  92. 92.
    Lezama IG et al (2015) Indirect-to-direct band gap crossover in few-layer MoTe2. Nano Lett 15:2336–2342CrossRefGoogle Scholar
  93. 93.
    Schmidt H, Giustiniano F, Eda G (2015) Electronic transport properties of transition metal dichalcogenide field-effect devices: surface and interface effects. Chem Soc Rev 44:7715–7736CrossRefGoogle Scholar
  94. 94.
    Zhao W, Mendes Ribeiro R, Eda G (2015) Electronic structure and optical signatures of semiconducting transition metal dichalcogenide nanosheets. Acc Chem Res 48:91–99CrossRefGoogle Scholar
  95. 95.
    Yoffe AD (2002) Low-dimensional systems: quantum size effects and electronic properties of semiconductor microcrystallites (zero-dimensional systems) and some quasi-two-dimensional systems. Adv Phys 51:799–890CrossRefGoogle Scholar
  96. 96.
    Cheiwchanchamnangij T, Lambrecht WRL (2012) Quasiparticle band structure calculation of monolayer, bilayer, and bulk MoS2. Phys Rev B 85:205302CrossRefGoogle Scholar
  97. 97.
    Tongay S et al (2013) Broad-range modulation of light emission in two-dimensional semiconductors by molecular physisorption gating. Nano Lett 13:2831–2836CrossRefGoogle Scholar
  98. 98.
    Komsa HP, Krasheninnikov AV (2012) Effects of confinement and environment on the electronic structure and exciton binding energy of MoS2 from first principles. Phys Rev B 86:241201CrossRefGoogle Scholar
  99. 99.
    Yu H et al (2015) Valley excitons in two-dimensional semiconductors. Natl Sci Rev 2:57–70CrossRefGoogle Scholar
  100. 100.
    Xu X et al (2014) Spin and pseudospins in layered transition metal dichalcogenides. Nat Phys 10:343–350CrossRefGoogle Scholar
  101. 101.
    Zhao W et al (2013) Origin of indirect optical transitions in few-layer MoS2, WS2, and WSe2. Nano Lett 13:5627–5634CrossRefGoogle Scholar
  102. 102.
    Mak KF et al (2013) Tightly bound trions in monolayer MoS2. Nat Mater 12:207–211CrossRefGoogle Scholar
  103. 103.
    You Y et al (2015) Observation of biexcitons in monolayer WSe2. Nat Phys 11:477–481CrossRefGoogle Scholar
  104. 104.
    Jones AM et al (2013) Optical generation of excitonic valley coherence in monolayer WSe2. Nat Nanotechnol 8:634–638CrossRefGoogle Scholar
  105. 105.
    Ross JS et al (2013) Electrical control of neutral and charged excitons in a monolayer semiconductor. Nat Commun 4:1474CrossRefGoogle Scholar
  106. 106.
    Castellanos-Gomez A et al (2013) Local strain engineering in atomically thin MoS2. Nano Lett 13:5361CrossRefGoogle Scholar
  107. 107.
    Conley HJ et al (2013) Bandgap engineering of strained monolayer and bilayer MoS2. Nano Lett 13:3626CrossRefGoogle Scholar
  108. 108.
    Qiu DY, da Jornada FH, Louie SG (2013) Optical spectrum of MoS2: many-body effects and diversity of exciton states. Phys Rev Lett 111:216805CrossRefGoogle Scholar
  109. 109.
    Beal AR, Hughes HP (1979) Kramers-Kronig analysis of the reflectivity spectra of 2H-MoS2, 2H-MoSe2 and 2H-MoTe2. J Phys C Solid Stat Phys 12:881CrossRefGoogle Scholar
  110. 110.
    Carvalho A, Ribeiro RM, Castro Neto AH (2013) Band nesting and the optical response of two-dimensional semiconducting transition metal dichalcogenides. Phys Rev B 88:115205CrossRefGoogle Scholar
  111. 111.
    Kumar R, Verzhbitskiy I, Eda G (2015) Strong optical absorption and photocarrier relaxation in two-dimensional semiconductors. IEEE J Quant Elec 51:0600206CrossRefGoogle Scholar
  112. 112.
    Britnell L et al (2013) Strong light-matter interactions in heterostructures of atomically thin films. Science 340:1311–1314CrossRefGoogle Scholar
  113. 113.
    Feng J et al (2012) Strain-engineered artificial atom as a broad-spectrum solar energy funnel. Nat Photon 6:865–871CrossRefGoogle Scholar
  114. 114.
    Nair RR et al (2008) Fine structure constant defines visual transparency of graphene. Science 320:1308CrossRefGoogle Scholar
  115. 115.
    Yun WS et al (2012) Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H-MX2 semiconductors (M=Mo, W; X=S, Se, Te). Phys Rev B 85:033305CrossRefGoogle Scholar
  116. 116.
    Kuc A, Zibouche N, Heine T (2011) Influence of quantum confinement on the electronic structure of the transition metal sulfide TS2. Phys Rev B 83:245213CrossRefGoogle Scholar
  117. 117.
    Ramasubramaniam A, Naveh D, Towe E (2011) Tunable band gaps in bilayer transition-metal dichalcogenides. Phys Rev B 84:205325CrossRefGoogle Scholar
  118. 118.
    Klein A et al (2001) Electronic band structure of single-crystal and single-layer WS2: influence of interlayer van der Waals interactions. Phys Rev B 64:205416CrossRefGoogle Scholar
  119. 119.
    Ugeda MM et al (2014) Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor. Nat Mater 13:1091–1095CrossRefGoogle Scholar
  120. 120.
    Chernikov A et al (2015) Electrical tuning of exciton binding energies in monolayer WS2. Phys Rev Lett 115:126802Google Scholar
  121. 121.
    Yuan H et al (2013) Zeeman-type spin splitting controlled by an electric field. Nat Phys 9:563–569CrossRefGoogle Scholar
  122. 122.
    Ruppert C, Aslan OB, Heinz TF (2014) Optical properties and band gap of single- and few-layer MoTe2 crystals. Nano Lett 14:6231–6236CrossRefGoogle Scholar
  123. 123.
    Py MA, Haering RR (1983) Structural destabilization induced by lithium intercalation in MoS2 and related compounds. Can J Phys 61:76–84CrossRefGoogle Scholar
  124. 124.
    Voiry D, Mohite A, Chhowalla M (2015) Phase engineering of transition metal dichalcogenides. Chem Soc Rev 44:2702–2712CrossRefGoogle Scholar
  125. 125.
    Eda G et al (2011) Photoluminescence from chemically exfoliated MoS2. Nano Lett 11:5111–5116CrossRefGoogle Scholar
  126. 126.
    Joensen P, Frindt RF, Morrison SR (1986) Single-layer MoS2. Mater Res Bull 21:457–461CrossRefGoogle Scholar
  127. 127.
    Papageorgopoulos CA, Jaegermann W (1995) Li intercalation across and along the van der Waals surfaces of MoS2 (0001). Surf Sci 338:83–93Google Scholar
  128. 128.
    Li LJ et al (2016) Controlling many-body states by the electric-field effect in a two-dimensional material. Nature 529:185–189Google Scholar
  129. 129.
    Zhang C et al (2014) Absorption of light by excitons and trions in monolayers of metal dichalcogenide MoS2: experiments and theory. Phys Rev B 89:205436Google Scholar
  130. 130.
    Nguyen DT et al (2011) Elastic exciton-exciton scattering in photoexcited carbon nanotubes. Phys Rev Lett 107:127401CrossRefGoogle Scholar
  131. 131.
    Qiu DY, da Jornada FH, Louie SG (2015) Erratum: optical spectrum of MoS2: many-body effects and diversity of exciton states. Phys Rev Lett 115:119901Google Scholar
  132. 132.
    Miller RC et al (1981) Observation of the excited level of excitons in GaAs quantum wells. Phys Rev B 24:1134CrossRefGoogle Scholar
  133. 133.
    Greene RL, Bajaj KK, Phelps DE (1984) Energy levels of Wannier excitons in GaAs−Ga1−xAlxAs quantum-well structures. Phys Rev B 29:1807CrossRefGoogle Scholar
  134. 134.
    Beal AR, Knights JC, Liang WY (1972) Transmission spectra of some transition metal dichalcogenides. II. Group VIA: trigonal prismatic coordination. Phys C Sol Stat Phys 5:3540–3551CrossRefGoogle Scholar
  135. 135.
    Klots AR et al (2014) Probing excitonic states in suspended two-dimensional semiconductors by photocurrent spectroscopy. Sci Rep 4:6608CrossRefGoogle Scholar
  136. 136.
    Hill HM et al (2015) Observation of excitonic rydberg states in monolayer MoS2 and WS2 by photoluminescence excitation spectroscopy. Nano Lett 13:2992–2997CrossRefGoogle Scholar
  137. 137.
    Zhu B, Chen X, Cui X (2015) Exciton binding energy of monolayer WS2. Sci Rep 5:9218CrossRefGoogle Scholar
  138. 138.
    Berkelbach TC, Hybertsen MS, Reichman DR (2013) Theory of neutral and charged excitons in monolayer transition metal dichalcogenides. Phys Rev B 88:045318CrossRefGoogle Scholar
  139. 139.
    Kheng K et al (1993) Observation of negatively charged excitons X in semiconductor quantum wells. Phys Rev Lett 71:1752CrossRefGoogle Scholar
  140. 140.
    Finkelstein G, Shtrikman H, Bar-Joseph I (1995) Optical spectroscopy of a two-dimensional electron gas near the metal-insulator transition. Phys Rev Lett 74:976CrossRefGoogle Scholar
  141. 141.
    Sergeev RA, Suris RA (2001) Ground-state energy of X and X+ trions in a two-dimensional quantum well at an arbitrary mass ratio. Phys Sol Stat 43:746–751CrossRefGoogle Scholar
  142. 142.
    Thilagam A (1997) Two-dimensional charged-exciton complexes. Phys Rev B 55:7804–7808CrossRefGoogle Scholar
  143. 143.
    Klingshirn CF (2007) Semiconductor Optics. Springer, BerlinCrossRefGoogle Scholar
  144. 144.
    He Z et al (2016) Biexciton formation in bilayer tungsten disulfide. ACS Nano 10:2176–2183CrossRefGoogle Scholar
  145. 145.
    Mai C et al (2014) Many-body effects in valleytronics: direct measurement of valley lifetimes in single-layer MoS2. Nano Lett 14:202–206CrossRefGoogle Scholar
  146. 146.
    Sie EJ et al (2015) Intervalley biexcitons and many-body effects in monolayer MoS2. Phys Rev B 92:125417Google Scholar
  147. 147.
    Mitioglu AA et al (2013) Optical manipulation of the exciton charge state in single-layer tungsten disulfide. Phys Rev B 88:245403CrossRefGoogle Scholar
  148. 148.
    Plechinger G et al (2015) Identification of excitons, trions and biexcitons in single-layer WS2. Phys Stat Sol RRL 9:457–467CrossRefGoogle Scholar
  149. 149.
    Shang J et al (2015) Observation of excitonic fine structure in a 2D transition-metal dichalcogenide semiconductor. ACS Nano 9:647–655CrossRefGoogle Scholar
  150. 150.
    Liu H et al (2014) Dense network of one-dimensional midgap metallic modes in monolayer MoSe2 and their spatial undulations. Phys Rev Lett 113:066105CrossRefGoogle Scholar
  151. 151.
    He K et al (2014) Tightly bound excitons in monolayer WSe2. Phys Rev Lett 113:026803CrossRefGoogle Scholar
  152. 152.
    Wang G et al (2015) Giant enhancement of the optical second-harmonic emission of WSe2 monolayers by laser excitation at exciton resonances. Phys Rev Lett 114:097403CrossRefGoogle Scholar
  153. 153.
    Yang J et al (2015) Robust excitons and trions in monolayer MoTe2. ACS Nano 9:6603–6609CrossRefGoogle Scholar
  154. 154.
    Zhu X et al (1995) Exciton condensate in semiconductor quantum well structures. Phys Rev Lett 74:1633CrossRefGoogle Scholar
  155. 155.
    Butov LV et al (2002) Towards Bose-Einstein condensation of excitons in potential traps. Nature 417:47–52CrossRefGoogle Scholar
  156. 156.
    Fox AM et al (1992) Suppression of the observation of Stark ladders in optical measurements on superlattices by excitonic effects. Phys Rev B 46:15365CrossRefGoogle Scholar
  157. 157.
    Kato Y et al (1994) Observation of the Stark effect in coupled quantum wells by electroluminescence and circularly polarized photoluminescence excitation spectroscopy. J Appl Phys 75:7476CrossRefGoogle Scholar
  158. 158.
    Schuller JA et al (2013) Orientation of luminescent excitons in layered nanomaterials. Nat Nanotechnol 8:271–276CrossRefGoogle Scholar
  159. 159.
    Jones AM et al (2014) Spin–layer locking effects in optical orientation of exciton spin in bilayer WSe2. Nat Phys 10:130–134CrossRefGoogle Scholar
  160. 160.
    Fang H et al (2014) Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides. PNAS 111:6198–6202CrossRefGoogle Scholar
  161. 161.
    Rivera P et al (2015) Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures. Nat Commun 6:6242CrossRefGoogle Scholar
  162. 162.
    Rivera P et al (2016) Valley-polarized exciton dynamics in a 2D semiconductor heterostructure. Science 351:688–691CrossRefGoogle Scholar
  163. 163.
    Li G, Zhu R, Yang Y (2012) Polymer solar cells. Nat Photonics 6:153–161CrossRefGoogle Scholar
  164. 164.
    Kośmider K, Fernández-Rossier J (2013) Electronic properties of the MoS2–WS2 heterojunction. Phys Rev B 87:075451CrossRefGoogle Scholar
  165. 165.
    Özçelik VO et al (2016) Band alignment of 2D semiconductors for designing heterostructures with momentum space matching. Phys Rev B 94:035125Google Scholar
  166. 166.
    Kang J et al (2013) Band offsets and heterostructures of two-dimensional semiconductors. Appl Phys Lett 102:012111Google Scholar
  167. 167.
    Terrones H, Lopez-Urias F, Terrones M (2013) Novel hetero-layered materials with tunable direct band gaps by sandwiching different metal disulfides and diselenides. Sci Rep 3:1549CrossRefGoogle Scholar
  168. 168.
    Yu H et al (2015) Anomalous light cones and valley optical selection rules of interlayer excitons in twisted heterobilayers. Phys Rev Lett 115:187002CrossRefGoogle Scholar
  169. 169.
    Lin Y-C et al (2015) Single-layer ReS2: two-dimensional semiconductor with tunable in-plane anisotropy. ACS Nano 9:11249–11257CrossRefGoogle Scholar
  170. 170.
    Dai J, Zeng XC (2015) Titanium trisulfide monolayer: theoretical prediction of a new direct-gap semiconductor with high and anisotropic carrier mobility. Angew Chem Int Ed 54:7572–7576CrossRefGoogle Scholar
  171. 171.
    Rodin AS et al (2016) Valley physics in tin (II) sulfide. Phys Rev B 93:045431CrossRefGoogle Scholar
  172. 172.
    Tritsaris GA, Malone BD, Kaxiras E (2013) Optoelectronic properties of single-layer, double-layer, and bulk tin sulfide: a theoretical study. J Appl Phys 113:233507CrossRefGoogle Scholar
  173. 173.
    Island JO et al (2015) TiS3 transistors with tailored morphology and electrical properties. Adv Mater 27:2595–2601CrossRefGoogle Scholar
  174. 174.
    Hu P et al (2012) Synthesis of few-layer GaSe nanosheets for high performance photodetectors. ACS Nano 6:5988–5994CrossRefGoogle Scholar
  175. 175.
    Ramakrishna Reddy KT, Koteswara Reddy N, Miles RW (2006) Photovoltaic properties of SnS based solar cells. Sol Energy Mater Sol Cells 90:3041–3046CrossRefGoogle Scholar
  176. 176.
    Schwarz S et al (2014) Two-dimensional metal−chalcogenide films in tunable optical microcavities. Nano Lett 14:7003–7008CrossRefGoogle Scholar
  177. 177.
    Zhao L-D et al (2014) Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals. Nature 508:373–377CrossRefGoogle Scholar
  178. 178.
    Li X et al (2014) Controlled vapor phase growth of single crystalline, two-dimensional GaSe crystals with high photoresponse. Sci Rep 4:5497Google Scholar
  179. 179.
    Hu P et al (2013) Highly responsive ultrathin GaS nanosheet photodetectors on rigid and flexible substrates. Nano Lett 13:1649–1654CrossRefGoogle Scholar
  180. 180.
    Liu F et al (2014) High-sensitivity photodetectors based on multilayer GaTe flakes. ACS Nano 8:752–760CrossRefGoogle Scholar
  181. 181.
    Sanchez-Royo JF et al (2002) Angle-resolved photoemission study and first-principles calculation of the electronic structure of GaTe. Phys Rev B 65:115201CrossRefGoogle Scholar
  182. 182.
    Zhang HL, Hennig RG (2003) Single-layer group-III monochalcogenide photocatalysts for water splitting. Chem Mater 25:3232–3238CrossRefGoogle Scholar
  183. 183.
    Jung CS et al (2015) Red-to-ultraviolet emission tuning of two-dimensional gallium sulfide/selenide. ACS Nano 9:9585–9593CrossRefGoogle Scholar
  184. 184.
    Ma Y et al (2013) Tunable electronic and dielectric behavior of GaS and GaSe monolayers. Phys Chem Chem Phys 15:7098–7105CrossRefGoogle Scholar
  185. 185.
    Li H et al (2014) Growth of alloy MoS2xSe2(1–x) nanosheets with fully tunable chemical compositions and optical properties. J Am Chem Soc 136:3756–3759CrossRefGoogle Scholar
  186. 186.
    Dumcenco DO et al (2013) Visualization and quantification of transition metal atomic mixing in Mo1–xWxS2 single layers. Nat Commun 4:1351Google Scholar
  187. 187.
    Zhang M et al (2014) Two-dimensional molybdenum tungsten diselenide alloys: photoluminescence, raman scattering, and electrical transport. ACS Nano 8:7130–7137CrossRefGoogle Scholar
  188. 188.
    Tongay S et al (2014) Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling. Nat Commun 5:3252CrossRefGoogle Scholar
  189. 189.
    Zhao H et al (2015) Interlayer interactions in anisotropic atomically thin rhenium diselenide. Nano Res 8:3651–3661CrossRefGoogle Scholar
  190. 190.
    Aslan OB et al (2016) Linearly polarized excitons in single- and few-layer ReS2 crystals. ACS Photon 3:96–101CrossRefGoogle Scholar
  191. 191.
    Chenet DA et al (2015) In-plane anisotropy in mono- and few-layer ReS2 probed by Raman spectroscopy and scanning transmission electron microscopy. Nano Lett 15:5667–5672CrossRefGoogle Scholar
  192. 192.
    Zhong H-X et al (2015) Quasiparticle band gaps, excitonic effects, and anisotropic optical properties of the monolayer distorted 1T diamond-chain structures ReS2 and ReSe2. Phys Rev B 92:115438Google Scholar
  193. 193.
    Jin Y, Li X, Yang J (2015) Single layer of MX3 (M=Ti, Zr; X=S, Se, Te): a new platform for nano-electronics and optics. Phys Chem Chem Phys 17:18665–18669CrossRefGoogle Scholar
  194. 194.
    Gorlova I et al (2012) Nonlinear conductivity of quasi-one-dimensional layered compound TiS3. Physica B 407:1707CrossRefGoogle Scholar
  195. 195.
    Zaitsev-Zotov SV, Pokrovskii V Ya, Monceau P (2001) Transition to 1D conduction with decreasing thickness of the crystals of TaS3 and NbSe3 quasi-1D conductors. J Exp Theor Phys Lett 73:25–27CrossRefGoogle Scholar
  196. 196.
    Slot E et al (2004) One-dimensional conduction in charge-density-wave nanowires. Phys Rev Lett 93:176602CrossRefGoogle Scholar
  197. 197.
    Island JO et al (2014) Ultrahigh photoresponse of few-layer TiS3 nanoribbon transistors. Adv Opt Mat 2:641–645Google Scholar
  198. 198.
    Island JO et al (2016) Titanium trisulfide (TiS3): a 2D semiconductor with quasi-1D optical and electronic properties. Sci Rep 6:22214Google Scholar

Copyright information

© Springer Japan KK 2017

Authors and Affiliations

  1. 1.Department of PhysicsNational University of SingaporeSingaporeSingapore
  2. 2.Department of ChemistryNational University of SingaporeSingaporeSingapore
  3. 3.Centre for Advanced 2D MaterialsNational University of SingaporeSingaporeSingapore

Personalised recommendations