[1] NOVOSELOV K S, GEIM A K, MOROZOV S V, et al. Electric field effect in atomically thin carbon films[J]. Science, 2004, 306(5696): 666-669. doi: 10.1126/science.1102896
[2] HAN P, WANG X K, ZHANG Y. Time-resolved terahertz spectroscopy studies on 2D van der Waals materials[J]. Advanced Optical Materials, 2020, 8(3): 1900533. doi: 10.1002/adom.201900533
[3] MOUNET N, GIBERTINI M, SCHWALLER P, et al. Two-dimensional materials from high-throughput computational exfoliation of experimentally known compounds[J]. Nature Nanotechnology, 2018, 13(3): 246-252. doi: 10.1038/s41565-017-0035-5
[4] CASTELLANOS-GOMEZ A. Why all the fuss about 2D semiconductors?[J]. Nature Photonics, 2016, 10(4): 202-204. doi: 10.1038/nphoton.2016.53
[5] AJAYAN P, KIM P, BANERJEE K. Two-dimensional van der Waals materials[J]. Physics Today, 2016, 69(9): 38-44. doi: 10.1063/PT.3.3297
[6] BERKELBACH T C, REICHMAN D R. Optical and excitonic properties of atomically thin transition-metal dichalcogenides[J]. Annual Review of Condensed Matter Physics, 2018, 9(1): 379-396. doi: 10.1146/annurev-conmatphys-033117-054009
[7] GUO B, XIAO Q L, WANG SH H, et al. 2D layered materials: synthesis, nonlinear optical properties, and device applications[J]. Laser &Photonics Reviews, 2019, 13(12): 1800327.
[8] KANG S, LEE D, KIM J, et al. 2D semiconducting materials for electronic and optoelectronic applications: potential and challenge[J]. 2D Materials, 2020, 7(2): 022003. doi: 10.1088/2053-1583/ab6267
[9] MUELLER T, MALIC E. Exciton physics and device application of two-dimensional transition metal dichalcogenide semiconductors[J]. npj 2D Materials and Applications, 2018, 2(1): 29. doi: 10.1038/s41699-018-0074-2
[10] TAN CH L, CAO X H, WU X J, et al. Recent advances in ultrathin two-dimensional nanomaterials[J]. Chemical Reviews, 2017, 117(9): 6225-6331. doi: 10.1021/acs.chemrev.6b00558
[11] XIA F N, WANG H, XIAO D, et al. Two-dimensional material nanophotonics[J]. Nature Photonics, 2014, 8(12): 899-907. doi: 10.1038/nphoton.2014.271
[12] MAK K F, LEE C, HONE J, et al. Atomically thin MoS2: A new direct-gap semiconductor[J]. Physical Review Letters, 2010, 105(13): 136805. doi: 10.1103/PhysRevLett.105.136805
[13] ROLDÁN R, SILVA-GUILLÉN J A, LÓPEZ-SANCHO M P, et al. Electronic properties of single-layer and multilayer transition metal dichalcogenides MX2 (M= Mo, W and X= S, Se)[J]. Annalen der Physik, 2014, 526(9-10): 347-357. doi: 10.1002/andp.201400128
[14] RUPPERT C, ASLAN O B, HEINZ T F. Optical properties and band gap of single- and few-layer MoTe2 crystals[J]. Nano Letters, 2014, 14(11): 6231-6236. doi: 10.1021/nl502557g
[15] SPLENDIANI A, SUN L, ZHANG Y B, et al. Emerging photoluminescence in monolayer MoS2[J]. Nano Letters, 2010, 10(4): 1271-1275. doi: 10.1021/nl903868w
[16] ZHAO W J, GHORANNEVIS Z, CHU L Q, et al. Evolution of electronic structure in atomically thin sheets of WS2 and WSe2[J]. ACS Nano, 2013, 7(1): 791-797. doi: 10.1021/nn305275h
[17] CHERNIKOV A, BERKELBACH T C, HILL H M, et al. Exciton binding energy and nonhydrogenic rydberg series in monolayer WS2[J]. Physical Review Letters, 2014, 113(7): 076802. doi: 10.1103/PhysRevLett.113.076802
[18] MAK K F, HE K L, LEE C, et al. Tightly bound trions in monolayer MoS2[J]. Nature Materials, 2013, 12(3): 207-211. doi: 10.1038/nmat3505
[19] PLECHINGER G, NAGLER P, ARORA A, et al. Trion fine structure and coupled spin–valley dynamics in monolayer tungsten disulfide[J]. Nature Communications, 2016, 7(1): 12715. doi: 10.1038/ncomms12715
[20] ROSS J S, WU S F, YU H Y, et al. Electrical control of neutral and charged excitons in a monolayer semiconductor[J]. Nature Communications, 2013, 4(1): 1474. doi: 10.1038/ncomms2498
[21] STEINHOFF A, FLORIAN M, SINGH A, et al. Biexciton fine structure in monolayer transition metal dichalcogenides[J]. Nature Physics, 2018, 14(12): 1199-1204. doi: 10.1038/s41567-018-0282-x
[22] YOU Y M, ZHANG X X, BERKELBACH T C, et al. Observation of biexcitons in monolayer WSe2[J]. Nature Physics, 2015, 11(6): 477-481. doi: 10.1038/nphys3324
[23] LI ZH P, WANG T M, LU ZH G, et al. Revealing the biexciton and trion-exciton complexes in BN encapsulated WSe2[J]. Nature Communications, 2018, 9(1): 3719. doi: 10.1038/s41467-018-05863-5
[24] KUMAR N, NAJMAEI S, CUI Q N, et al. Second harmonic microscopy of monolayer MoS2[J]. Physical Review B, 2013, 87(16): 161403. doi: 10.1103/PhysRevB.87.161403
[25] LI Y L, RAO Y, MAK K F, et al. Probing symmetry properties of few-layer MoS2 and h-BN by optical second-harmonic generation[J]. Nano Letters, 2013, 13(7): 3329-3333. doi: 10.1021/nl401561r
[26] MALARD L M, ALENCAR T V, BARBOZA A P M, et al. Observation of intense second harmonic generation from MoS2 atomic crystals[J]. Physical Review B, 2013, 87(20): 201401. doi: 10.1103/PhysRevB.87.201401
[27] CAO T, WANG G, HAN W P, et al. Valley-selective circular dichroism of monolayer molybdenum disulphide[J]. Nature Communications, 2012, 3(1): 887. doi: 10.1038/ncomms1882
[28] MAK K F, HE K L, SHAN J, et al. Control of valley polarization in monolayer MoS2 by optical helicity[J]. Nature Nanotechnology, 2012, 7(8): 494-498. doi: 10.1038/nnano.2012.96
[29] ZENG H L, DAI J F, YAO W, et al. Valley polarization in MoS2 monolayers by optical pumping[J]. Nature Nanotechnology, 2012, 7(8): 490-493. doi: 10.1038/nnano.2012.95
[30] UBRIG N, PONOMAREV E, ZULTAK J, et al. Design of van der Waals interfaces for broad-spectrum optoelectronics[J]. Nature Materials, 2020, 19(3): 299-304. doi: 10.1038/s41563-019-0601-3
[31] RIVERA P, SCHAIBLEY J R, JONES A M, et al. Observation of long-lived interlayer excitons in monolayer MoSe2-WSe2 heterostructures[J]. Nature Communications, 2015, 6(1): 6242. doi: 10.1038/ncomms7242
[32] ALEXEEV E M, RUIZ-TIJERINA D A, DANOVICH M, et al. Resonantly hybridized excitons in Moire superlattices in van der Waals heterostructures[J]. Nature, 2019, 567(7746): 81-86. doi: 10.1038/s41586-019-0986-9
[33] JIN CH H, REGAN E C, YAN A M, et al. Observation of Moire excitons in WSe2/WS2 heterostructure superlattices[J]. Nature, 2019, 567(7746): 76-80. doi: 10.1038/s41586-019-0976-y
[34] TRAN K, MOODY G, WU F CH, et al. Evidence for Moire excitons in van der Waals heterostructures[J]. Nature, 2019, 567(7746): 71-75. doi: 10.1038/s41586-019-0975-z
[35] RADISAVLJEVIC B, RADENOVIC A, BRIVIO J, et al. Single-layer MoS2 transistors[J]. Nature Nanotechnology, 2011, 6(3): 147-150. doi: 10.1038/nnano.2010.279
[36] BAO W ZH, CAI X H, KIM D, et al. High mobility ambipolar MoS2 field-effect transistors: substrate and dielectric effects[J]. Applied Physics Letters, 2013, 102(4): 042104. doi: 10.1063/1.4789365
[37] BIE Y Q, GROSSO G, HEUCK M, et al. A MoTe2-based light-emitting diode and photodetector for silicon photonic integrated circuits[J]. Nature Nanotechnology, 2017, 12(12): 1124-1129. doi: 10.1038/nnano.2017.209
[38] XIE Y, ZHANG B, WANG SH X, et al. Ultrabroadband MoS2 photodetector with spectral response from 445 to 2717 nm[J]. Advanced Materials, 2017, 29(17): 1605972. doi: 10.1002/adma.201605972
[39] LIU CH H, CLARK G, FRYETT T, et al. Nanocavity integrated van der Waals heterostructure light-emitting tunneling diode[J]. Nano Letters, 2017, 17(1): 200-205. doi: 10.1021/acs.nanolett.6b03801
[40] PU J, TAKENOBU T. Monolayer transition metal dichalcogenides as light sources[J]. Advanced Materials, 2018, 30(33): 1707627. doi: 10.1002/adma.201707627
[41] GE X CH, MINKOV M, FAN SH H, et al. Laterally confined photonic crystal surface emitting laser incorporating monolayer tungsten disulfide[J]. npj 2D Materials and Applications, 2019, 3(1): 16. doi: 10.1038/s41699-019-0099-1
[42] LI Y ZH, ZHANG J X, HUANG D D, et al. Room-temperature continuous-wave lasing from monolayer molybdenum ditelluride integrated with a silicon nanobeam cavity[J]. Nature Nanotechnology, 2017, 12(10): 987-992. doi: 10.1038/nnano.2017.128
[43] PAIK E Y, ZHANG L, BURG G W, et al. Interlayer exciton laser of extended spatial coherence in atomically thin heterostructures[J]. Nature, 2019, 576(7785): 80-84. doi: 10.1038/s41586-019-1779-x
[44] WU S F, BUCKLEY S, SCHAIBLEY J R, et al. Monolayer semiconductor nanocavity lasers with ultralow thresholds[J]. Nature, 2015, 520(7545): 69-72. doi: 10.1038/nature14290
[45] FAVRON A, GAUFRÈS E, FOSSARD F, et al. Photooxidation and quantum confinement effects in exfoliated black phosphorus[J]. Nature Materials, 2015, 14(8): 826-832. doi: 10.1038/nmat4299
[46] NACLERIO A E, ZAKHAROV D N, KUMAR J, et al. Visualizing oxidation mechanisms in few-layered black phosphorus via in situ transmission electron microscopy[J]. ACS Applied Materials &Interfaces, 2020, 12(13): 15844-15854.
[47] NAN H Y, GUO S J, CAI SH, et al. Producing air-stable inse nanosheet through mild oxygen plasma treatment[J]. Semiconductor Science and Technology, 2018, 33(7): 074002. doi: 10.1088/1361-6641/aac3e6
[48] HUANG Y, SUTTER E, SHI N N, et al. Reliable exfoliation of large-area high-quality flakes of graphene and other two-dimensional materials[J]. ACS Nano, 2015, 9(11): 10612-10620. doi: 10.1021/acsnano.5b04258
[49] HUANG Y, PAN Y H, YANG R, et al. Universal mechanical exfoliation of large-area 2D crystals[J]. Nature Communications, 2020, 11(1): 2453. doi: 10.1038/s41467-020-16266-w
[50] LIU F, WU W J, BAI Y S, et al. Disassembling 2D van der Waals crystals into macroscopic monolayers and reassembling into artificial lattices[J]. Science, 2020, 367(6480): 903-906. doi: 10.1126/science.aba1416
[51] SHIM J, BAE S H, KONG W, et al. Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials[J]. Science, 2018, 362(6415): 665-670. doi: 10.1126/science.aat8126
[52] BERNAL M M, ÁLVAREZ L, GIOVANELLI E, et al. Luminescent transition metal dichalcogenide nanosheets through one-step liquid phase exfoliation[J]. 2D Materials, 2016, 3(3): 035014. doi: 10.1088/2053-1583/3/3/035014
[53] JAWAID A, NEPAL D, PARK K, et al. Mechanism for liquid phase exfoliation of MoS2[J]. Chemistry of Materials, 2016, 28(1): 337-348. doi: 10.1021/acs.chemmater.5b04224
[54] QI ZH H, HU Y, JIN ZH, et al. Tuning the liquid-phase exfoliation of arsenic nanosheets by interaction with various solvents[J]. Physical Chemistry Chemical Physics, 2019, 21(23): 12087-12090. doi: 10.1039/C9CP01052A
[55] SHREE S, GEORGE A, LEHNERT T, et al. High optical quality of MoS2 monolayers grown by chemical vapor deposition[J]. 2D Materials, 2019, 7(1): 015011. doi: 10.1088/2053-1583/ab4f1f
[56] YU H, LIAO M ZH, ZHAO W J, et al. Wafer-scale growth and transfer of highly-oriented monolayer MoS2 continuous films[J]. ACS Nano, 2017, 11(12): 12001-12007. doi: 10.1021/acsnano.7b03819
[57] HU Y, CHEN T, WANG X Q, et al. Controlled growth and photoconductive properties of hexagonal SnS2 nanoflakes with mesa-shaped atomic steps[J]. Nano Research, 2017, 10(4): 1434-1447. doi: 10.1007/s12274-017-1525-3
[58] CHEN M W, OVCHINNIKOV D, LAZAR S, et al. Highly oriented atomically thin ambipolar MoSe2 grown by molecular beam epitaxy[J]. ACS Nano, 2017, 11(6): 6355-6361. doi: 10.1021/acsnano.7b02726
[59] HU Y, QI ZH H, LU J Y, et al. Van der Waals epitaxial growth and interfacial passivation of two-dimensional single-crystalline few-layer gray arsenic nanoflakes[J]. Chemistry of Materials, 2019, 31(12): 4524-4535. doi: 10.1021/acs.chemmater.9b01151
[60] FU D Y, ZHAO X X, ZHANG Y Y, et al. Molecular beam epitaxy of highly crystalline monolayer molybdenum disulfide on hexagonal boron nitride[J]. Journal of the American Chemical Society, 2017, 139(27): 9392-9400. doi: 10.1021/jacs.7b05131
[61] NAKANO M, WANG Y, KASHIWABARA Y, et al. Layer-by-layer epitaxial growth of scalable WSe2 on sapphire by molecular beam epitaxy[J]. Nano Letters, 2017, 17(9): 5595-5599. doi: 10.1021/acs.nanolett.7b02420
[62] WANG H N, ZHANG CH J, RANA F. Ultrafast dynamics of defect-assisted electron-hole recombination in monolayer MoS2[J]. Nano Letters, 2015, 15(1): 339-345. doi: 10.1021/nl503636c
[63] LI L Q, LIN M F, ZHANG X, et al. Phonon-suppressed auger scattering of charge carriers in defective two-dimensional transition metal dichalcogenides[J]. Nano Letters, 2019, 19(9): 6078-6086. doi: 10.1021/acs.nanolett.9b02005
[64] LI Y L, LIU W, WANG Y K, et al. Ultrafast electron cooling and decay in monolayer WS2 revealed by time- and energy-resolved photoemission electron microscopy[J]. Nano Letters, 2020, 20(5): 3747-3753. doi: 10.1021/acs.nanolett.0c00742
[65] LIU H, WANG CH, ZUO ZH G, et al. Direct visualization of exciton transport in defective few-layer WS2 by ultrafast microscopy[J]. Advanced Materials, 2020, 32(2): 1906540. doi: 10.1002/adma.201906540
[66] LI L SH, CARTER E A. Defect-mediated charge-carrier trapping and nonradiative recombination in WSe2 monolayers[J]. Journal of the American Chemical Society, 2019, 141(26): 10451-10461. doi: 10.1021/jacs.9b04663
[67] AMANI M, LIEN D H, KIRIYA D, et al. Near-unity photoluminescence quantum yield in MoS2[J]. Science, 2015, 350(6264): 1065-1068. doi: 10.1126/science.aad2114
[68] WU ZH T, LUO ZH ZH, SHEN Y T, et al. Defects as a factor limiting carrier mobility in WSe2: a spectroscopic investigation[J]. Nano Research, 2016, 9(12): 3622-3631. doi: 10.1007/s12274-016-1232-5
[69] TOSUN M, CHAN L, AMANI M, et al. Air-stable n-doping of WSe2 by anion vacancy formation with mild plasma treatment[J]. ACS Nano, 2016, 10(7): 6853-6860. doi: 10.1021/acsnano.6b02521
[70] CHEE S S, LEE W J, JO Y R, et al. Atomic vacancy control and elemental substitution in a monolayer molybdenum disulfide for high performance optoelectronic device arrays[J]. Advanced Functional Materials, 2020, 30(11): 1908147. doi: 10.1002/adfm.201908147
[71] YANG J, KAWAI H, WONG C P Y, et al. Electrical doping effect of vacancies on monolayer MoS2[J]. The Journal of Physical Chemistry C, 2019, 123(5): 2933-2939. doi: 10.1021/acs.jpcc.8b10496
[72] CHEE S S, LEE J H, LEE K, et al. Defect-assisted contact property enhancement in a molybdenum disulfide monolayer[J]. ACS Applied Materials &Interfaces, 2020, 12(3): 4129-4134.
[73] XIE Y, WU E X, HU R X, et al. Enhancing electronic and optoelectronic performances of tungsten diselenide by plasma treatment[J]. Nanoscale, 2018, 10(26): 12436-12444. doi: 10.1039/C8NR02668H
[74] YIN L, HE P, CHENG R, et al. Robust trap effect in transition metal dichalcogenides for advanced multifunctional devices[J]. Nature Communications, 2019, 10(1): 4133. doi: 10.1038/s41467-019-12200-x
[75] KOPERSKI M, NOGAJEWSKI K, ARORA A, et al. Single photon emitters in exfoliated WSe2 structures[J]. Nature Nanotechnology, 2015, 10(6): 503-506. doi: 10.1038/nnano.2015.67
[76] HE Y M, CLARK G, SCHAIBLEY J R, et al. Single quantum emitters in monolayer semiconductors[J]. Nature Nanotechnology, 2015, 10(6): 497-502. doi: 10.1038/nnano.2015.75
[77] SRIVASTAVA A, SIDLER M, ALLAIN A V, et al. Optically active quantum dots in monolayer WSe2[J]. Nature Nanotechnology, 2015, 10(6): 491-496. doi: 10.1038/nnano.2015.60
[78] MOODY G, TRAN K, LU X B, et al. Microsecond valley lifetime of defect-bound excitons in monolayer WSe2[J]. Physical Review Letters, 2018, 121(5): 057403. doi: 10.1103/PhysRevLett.121.057403
[79] REFAELY-ABRAMSON S, QIU D Y, LOUIE S G, et al. Defect-induced modification of low-lying excitons and valley selectivity in monolayer transition metal dichalcogenides[J]. Physical Review Letters, 2018, 121(16): 167402. doi: 10.1103/PhysRevLett.121.167402
[80] WANG Q SH, GE SH F, LI X, et al. Valley carrier dynamics in monolayer molybdenum disulfide from helicity-resolved ultrafast pump–probe spectroscopy[J]. ACS Nano, 2013, 7(12): 11087-11093. doi: 10.1021/nn405419h
[81] WANG SH SH, ROBERTSON A, WARNER J H. Atomic structure of defects and dopants in 2D layered transition metal dichalcogenides[J]. Chemical Society Reviews, 2018, 47(17): 6764-6794. doi: 10.1039/C8CS00236C
[82] WU ZH T, NI ZH H. Spectroscopic investigation of defects in two-dimensional materials[J]. Nanophotonics, 2017, 6(6): 1219-1237. doi: 10.1515/nanoph-2016-0151
[83] JIANG J, XU T, LU J P, et al. Defect engineering in 2D materials: precise manipulation and improved functionalities[J]. Research, 2019, 2019: 4641739.
[84] LIN ZH, CARVALHO B R, KAHN E, et al. Defect engineering of two-dimensional transition metal dichalcogenides[J]. 2D Materials, 2016, 3(2): 022002. doi: 10.1088/2053-1583/3/2/022002
[85] ZHOU W, ZOU X L, NAJMAEI S, et al. Intrinsic structural defects in monolayer molybdenum disulfide[J]. Nano Letters, 2013, 13(6): 2615-2622. doi: 10.1021/nl4007479
[86] AMANI M, TAHERI P, ADDOU R, et al. Recombination kinetics and effects of superacid treatment in sulfur- and selenium-based transition metal dichalcogenides[J]. Nano Letters, 2016, 16(4): 2786-2791. doi: 10.1021/acs.nanolett.6b00536
[87] HONG J H, HU ZH X, PROBERT M, et al. Exploring atomic defects in molybdenum disulphide monolayers[J]. Nature Communications, 2015, 6(1): 6293. doi: 10.1038/ncomms7293
[88] SCHULER B, QIU D Y, REFAELY-ABRAMSON S, et al. Large spin-orbit splitting of deep in-gap defect states of engineered sulfur vacancies in monolayer WS2[J]. Physical Review Letters, 2019, 123(7): 076801. doi: 10.1103/PhysRevLett.123.076801
[89] CHEN P, SHANG J M, YANG Y, et al. Annealing tunes interlayer coupling and optoelectronic property of bilayer SnSe2/MoSe2 heterostructures[J]. Applied Surface Science, 2017, 419: 460-464. doi: 10.1016/j.apsusc.2017.04.244
[90] HE ZH Y, WANG X CH, XU W SH, et al. Revealing defect-state photoluminescence in monolayer WS2 by cryogenic laser processing[J]. ACS Nano, 2016, 10(6): 5847-5855. doi: 10.1021/acsnano.6b00714
[91] PETŐ J, OLLÁR T, VANCSÓ P, et al. Spontaneous doping of the basal plane of MoS2 single layers through oxygen substitution under ambient conditions[J]. Nature Chemistry, 2018, 10(12): 1246-1251. doi: 10.1038/s41557-018-0136-2
[92] BARJA S, REFAELY-ABRAMSON S, SCHULER B, et al. Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides[J]. Nature Communications, 2019, 10(1): 3382. doi: 10.1038/s41467-019-11342-2
[93] SCHULER B, LEE J H, KASTL C, et al. How substitutional point defects in two-dimensional WS2 induce charge localization, spin-orbit splitting, and strain[J]. ACS Nano, 2019, 13(9): 10520-10534. doi: 10.1021/acsnano.9b04611
[94] AGHAJANIAN M, SCHULER B, COCHRANE K A, et al. Resonant and bound states of charged defects in two-dimensional semiconductors[J]. Physical Review B, 2020, 101(8): 081201. doi: 10.1103/PhysRevB.101.081201
[95] CHEN M, HAM H, WI S, et al. Multibit data storage states formed in plasma-treated MoS2 transistors[J]. Acs Nano, 2014, 8(4): 4023-4032.
[96] HU Z H, WU ZH T, HAN CH, et al. Two-dimensional transition metal dichalcogenides: Interface and defect engineering[J]. Chemical Society Reviews, 2018, 47(9): 3100-3128. doi: 10.1039/C8CS00024G
[97] ZAN R, RAMASSE Q M, JALIL R, et al. Control of radiation damage in MoS2 by graphene encapsulation[J]. ACS Nano, 2013, 7(11): 10167-10174. doi: 10.1021/nn4044035
[98] KOMSA H P, KOTAKOSKI J, KURASCH S, et al. Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping[J]. Physical Review Letters, 2012, 109(3): 035503. doi: 10.1103/PhysRevLett.109.035503
[99] WALKER II R C, SHI T, SILVA E C, et al. Radiation effects on two-dimensional materials[J]. Physica Status Solidi (A), 2016, 213(12): 3065-3077. doi: 10.1002/pssa.201600395
[100] ZHAO G Y, DENG H, TYREE N, et al. Recent progress on irradiation-induced defect engineering of two-dimensional 2H-MoS2 few layers[J]. Applied Sciences, 2019, 9(4): 678. doi: 10.3390/app9040678
[101] CHOW P K, JACOBS-GEDRIM R B, GAO J, et al. Defect-induced photoluminescence in monolayer semiconducting transition metal dichalcogenides[J]. ACS Nano, 2015, 9(2): 1520-1527. doi: 10.1021/nn5073495
[102] TONGAY S, SUH J, ATACA C, et al. Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons[J]. Scientific Reports, 2013, 3: 2657. doi: 10.1038/srep02657
[103] WU ZH T, ZHAO W W, JIANG J, et al. Defect activated photoluminescence in WSe2 monolayer[J]. The Journal of Physical Chemistry C, 2017, 121(22): 12294-12299. doi: 10.1021/acs.jpcc.7b03585
[104] MITTERREITER E, SCHULER B, COCHRANE K A, et al. Atomistic positioning of defects in helium ion treated single layer MoS2[J]. Nano Letters, 2020, 20(6): 4437-4444.
[105] MENG J L, WEI ZH, TANG J, et al. Employing defected monolayer MoS2 as charge storage materials[J]. Nanotechnology, 2020, 31(23): 235710. doi: 10.1088/1361-6528/ab7c47
[106] ZHANG SH, WANG CH G, LI M Y, et al. Defect structure of localized excitons in a WSe2 monolayer[J]. Physical Review Letters, 2017, 119(4): 046101. doi: 10.1103/PhysRevLett.119.046101
[107] ZHENG Y J, CHEN Y F, HUANG Y L, et al. Point defects and localized excitons in 2D WSe2[J]. ACS Nano, 2019, 13(5): 6050-6059. doi: 10.1021/acsnano.9b02316
[108] LEE Y, YUN S J, KIM Y, et al. Near-field spectral mapping of individual exciton complexes of monolayer WS2 correlated with local defects and charge population[J]. Nanoscale, 2017, 9(6): 2272-2278. doi: 10.1039/C6NR08813A
[109] KUMAR R, VERZHBITSKIY I, EDA G. Strong optical absorption and photocarrier relaxation in 2-D semiconductors[J]. IEEE Journal of Quantum Electronics, 2015, 51(10): 0600206.
[110] GREBEN K, ARORA S, HARATS M G, et al. Intrinsic and extrinsic defect-related excitons in TMDCs[J]. Nano Letters, 2020, 20(4): 2544-2550. doi: 10.1021/acs.nanolett.9b05323
[111] JADCZAK J, KUTROWSKA-GIRZYCKA J, KAPUŚCIŃSKI P, et al. Probing of free and localized excitons and trions in atomically thin WSe2, WS2, MoSe2 and MoS2 in photoluminescence and reflectivity experiments[J]. Nanotechnology, 2017, 28(39): 395702. doi: 10.1088/1361-6528/aa87d0
[112] SHANG J ZH, CONG CH X, SHEN X N, et al. Revealing electronic nature of broad bound exciton bands in two-dimensional semiconducting WS2 and MoS2[J]. Physical Review Materials, 2017, 1(7): 074001. doi: 10.1103/PhysRevMaterials.1.074001
[113] WIERZBOWSKI J, KLEIN J, SIGGER F, et al. Direct exciton emission from atomically thin transition metal dichalcogenide heterostructures near the lifetime limit[J]. Scientific Reports, 2017, 7(1): 12383. doi: 10.1038/s41598-017-09739-4
[114] YU Y, DANG J CH, QIAN CH J, et al. Many-body effect of mesoscopic localized states in MoS2 monolayer[J]. Physical Review Materials, 2019, 3(5): 051001. doi: 10.1103/PhysRevMaterials.3.051001
[115] CAROZO V, WANG Y X, FUJISAWA K, et al. Optical identification of sulfur vacancies: Bound excitons at the edges of monolayer tungsten disulfide[J]. Science Advances, 2017, 3(4): e1602813. doi: 10.1126/sciadv.1602813
[116] KATO T, KANEKO T. Optical detection of a highly localized impurity state in monolayer tungsten disulfide[J]. ACS Nano, 2014, 8(12): 12777-12785. doi: 10.1021/nn5059858
[117] MOLAS M R, NOGAJEWSKI K, SLOBODENIUK A O, et al. The optical response of monolayer, few-layer and bulk tungsten disulfide[J]. Nanoscale, 2017, 9(35): 13128-13141. doi: 10.1039/C7NR04672C
[118] GORDO V O, BALANTA M A G, GOBATO Y G, et al. Revealing the nature of low-temperature photoluminescence peaks by laser treatment in van der Waals epitaxially grown WS2 monolayers[J]. Nanoscale, 2018, 10(10): 4807-4815. doi: 10.1039/C8NR00719E
[119] VENANZI T, ARORA H, ERBE A, et al. Exciton localization in MoSe2 monolayers induced by adsorbed gas molecules[J]. Applied Physics Letters, 2019, 114(17): 172106. doi: 10.1063/1.5094118
[120] HE Z Y, ZHAO R, CHEN X F, et al. Defect engineering in single-layer MoS2 using heavy ion irradiation[J]. ACS Applied Materials &Interfaces, 2018, 10(49): 42524-42533.
[121] LEE C, JEONG B G, YUN S J, et al. Unveiling defect-related raman mode of monolayer WS2 via tip-enhanced resonance raman scattering[J]. ACS Nano, 2018, 12(10): 9982-9990. doi: 10.1021/acsnano.8b04265
[122] MIGNUZZI S, POLLARD A J, BONINI N, et al. Effect of disorder on raman scattering of single-layer MoS2[J]. Physical Review B, 2015, 91(19): 195411. doi: 10.1103/PhysRevB.91.195411
[123] SHI W, LIN M L, TAN Q H, et al. Raman and photoluminescence spectra of two-dimensional nanocrystallites of monolayer WS2 and WSe2[J]. 2D Materials, 2016, 3(2): 025016. doi: 10.1088/2053-1583/3/2/025016
[124] SHI W, ZHANG X, LI X L, et al. Phonon confinement effect in two-dimensional nanocrystallites of monolayer MoS2 to probe phonon dispersion trends away from brillouin-zone center[J]. Chinese Physics Letters, 2016, 33(5): 057801. doi: 10.1088/0256-307X/33/5/057801
[125] ZHANG X, QIAO X F, SHI W, et al. Phonon and raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material[J]. Chemical Society Reviews, 2015, 44(9): 2757-2785. doi: 10.1039/C4CS00282B
[126] WANG J Y, VERZHBITSKIY I, EDA G. Electroluminescent devices based on 2D semiconducting transition metal dichalcogenides[J]. Advanced Materials, 2018, 30(47): e1802687. doi: 10.1002/adma.201802687
[127] PAUR M, MOLINA-MENDOZA A J, BRATSCHITSCH R, et al. Electroluminescence from multi-particle exciton complexes in transition metal dichalcogenide semiconductors[J]. Nature Communications, 2019, 10(1): 1709. doi: 10.1038/s41467-019-09781-y
[128] POSPISCHIL A, FURCHI M M, MUELLER T. Solar-energy conversion and light emission in an atomic monolayer p-n diode[J]. Nature Nanotechnology, 2014, 9(4): 257-261. doi: 10.1038/nnano.2014.14
[129] ROSS J S, RIVERA P, SCHAIBLEY J, et al. Interlayer exciton optoelectronics in a 2D heterostructure p-n junction[J]. Nano Letters, 2017, 17(2): 638-643. doi: 10.1021/acs.nanolett.6b03398
[130] CLARK G, SCHAIBLEY J R, ROSS J, et al. Single defect light-emitting diode in a van der Waals heterostructure[J]. Nano Letters, 2016, 16(6): 3944-3948. doi: 10.1021/acs.nanolett.6b01580
[131] SCHWARZ S, KOZIKOV A, WITHERS F, et al. Electrically pumped single-defect light emitters in WSe2[J]. 2D Materials, 2016, 3(2): 025038. doi: 10.1088/2053-1583/3/2/025038
[132] PALACIOS-BERRAQUERO C, BARBONE M, KARA D M, et al. Atomically thin quantum light-emitting diodes[J]. Nature Communications, 2016, 7: 12978. doi: 10.1038/ncomms12978
[133] SCHULER B, COCHRANE K A, KASTL C, et al. Electrically driven photon emission from individual atomic defects in monolayer WS2[J]. Science advances, 2020, 6(38): eabb5988. doi: 10.1126/sciadv.abb5988
[134] KIM H, LIEN D H, AMANI M, et al. Highly stable near-unity photoluminescence yield in monolayer MoS2 by fluoropolymer encapsulation and superacid treatment[J]. ACS Nano, 2017, 11(5): 5179-5185. doi: 10.1021/acsnano.7b02521
[135] GOODMAN A J, WILLARD A P, TISDALE W A. Exciton trapping is responsible for the long apparent lifetime in acid-treated MoS2[J]. Physical Review B, 2017, 96(12): 121404. doi: 10.1103/PhysRevB.96.121404
[136] BRETSCHER H M, LI Z J, XIAO J, et al.. The bright side of defects in MoS2 and WS2 and a generalizable chemical treatment protocol for defect passivation[J]. arXiv preprint arXiv, 2020, 2002.03956.
[137] TANOH A O A, ALEXANDER-WEBBER J, XIAO J, et al. Enhancing photoluminescence and mobilities in WS2 monolayers with oleic acid ligands[J]. Nano Letters, 2019, 19(9): 6299-6307. doi: 10.1021/acs.nanolett.9b02431
[138] HAN H V, LU A Y, LU L S, et al. Photoluminescence enhancement and structure repairing of monolayer MoSe2 by hydrohalic acid treatment[J]. ACS Nano, 2016, 10(1): 1454-1461. doi: 10.1021/acsnano.5b06960
[139] TANOH A O A, XIAO J, ALEXANDER-WEBBER J, et al.. Giant photoluminescence enhancement in MoSe2 monolayers treated with oleic acid ligands[J]. arXiv preprint arXiv, 2006.04505, 2020.
[140] KIM H, AHN G H, CHO J, et al. Synthetic WSe2 monolayers with high photoluminescence quantum yield[J]. Science Advances, 2019, 5(1): eaau4728. doi: 10.1126/sciadv.aau4728
[141] LIEN D H, UDDIN S Z, YEH M, et al. Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors[J]. Science, 2019, 364(6439): 468-471. doi: 10.1126/science.aaw8053
[142] STRIKHA M V, KURCHAK A I, MOROZOVSKA A N. Gate-voltage control of quantum yield in monolayer transition-metal dichalcogenide[J]. Physical Review Applied, 2020, 13(1): 014040. doi: 10.1103/PhysRevApplied.13.014040
[143] ATALLAH T L, WANG J, BOSCH M, et al. Electrostatic screening of charged defects in monolayer MoS2[J]. Journal of Physical Chemistry Letters, 2017, 8(10): 2148-2152. doi: 10.1021/acs.jpclett.7b00710
[144] NAN H Y, WANG Z L, WANG W H, et al. Strong photoluminescence enhancement of MoS2 through defect engineering and oxygen bonding[J]. ACS Nano, 2014, 8(6): 5738-5745. doi: 10.1021/nn500532f
[145] LU J P, CARVALHO A, CHAN X K, et al. Atomic healing of defects in transition metal dichalcogenides[J]. Nano Letters, 2015, 15(5): 3524-3532. doi: 10.1021/acs.nanolett.5b00952
[146] OH H M, HAN G H, KIM H, et al. Photochemical reaction in monolayer MoS2 via correlated photoluminescence, raman spectroscopy, and atomic force microscopy[J]. ACS Nano, 2016, 10(5): 5230-5236. doi: 10.1021/acsnano.6b00895
[147] ARDEKANI H, YOUNTS R, YU Y L, et al. Reversible photoluminescence tuning by defect passivation via laser irradiation on aged monolayer MoS2[J]. ACS Applied Materials &Interfaces, 2019, 11(41): 38240-38246.
[148] LEE Y, GHIMIRE G, ROY S, et al. Impeding exciton–exciton annihilation in monolayer WS2 by laser irradiation[J]. ACS Photonics, 2018, 5(7): 2904-2911. doi: 10.1021/acsphotonics.8b00249
[149] VENKATAKRISHNAN A, CHUA H, TAN P, et al. Microsteganography on WS2 monolayers tailored by direct laser painting[J]. ACS Nano, 2017, 11(1): 713-720. doi: 10.1021/acsnano.6b07118
[150] SIVARAM S V, HANBICKI A T, ROSENBERGER M R, et al. Spatially selective enhancement of photoluminescence in MoS2 by exciton-mediated adsorption and defect passivation[J]. ACS Applied Materials &Interfaces, 2019, 11(17): 16147-16155.
[151] WANG W F, SHU H B, WANG J, et al. Defect passivation and photoluminescence enhancement of monolayer MoS2 crystals through sodium halide-assisted chemical vapor deposition growth[J]. ACS Applied Materials &Interfaces, 2020, 12(8): 9563-9571.
[152] ZHU Y, YI H, HAO Q Y, et al. Scalable synthesis and defect modulation of large monolayer WS2 via annealing in H2S atmosphere/thiol treatment to enhance photoluminescence[J]. Applied Surface Science, 2019, 485: 101-107. doi: 10.1016/j.apsusc.2019.04.168
[153] NIE ZH G, LONG R, SUN L F, et al. Ultrafast carrier thermalization and cooling dynamics in few-layer MoS2[J]. ACS Nano, 2014, 8(10): 10931-10940. doi: 10.1021/nn504760x
[154] CEBALLOS F, CUI Q N, BELLUS M Z, et al. Exciton formation in monolayer transition metal dichalcogenides[J]. Nanoscale, 2016, 8(22): 11681-11688. doi: 10.1039/C6NR02516A
[155] SHI H Y, YAN R S, BERTOLAZZI S, et al. Exciton dynamics in suspended monolayer and few-layer MoS2 2D crystals[J]. ACS Nano, 2013, 7(2): 1072-1080. doi: 10.1021/nn303973r
[156] ZIPFEL J, KULIG M, PEREA-CAUSÍN R, et al. Exciton diffusion in monolayer semiconductors with suppressed disorder[J]. Physical Review B, 2020, 101(11): 115430. doi: 10.1103/PhysRevB.101.115430
[157] LIU H, WANG CH, LIU D M, et al. Neutral and defect-induced exciton annihilation in defective monolayer WS2[J]. Nanoscale, 2019, 11(16): 7913-7920. doi: 10.1039/C9NR00967A
[158] KAR S, SU Y, NAIR R R, et al. Probing photoexcited carriers in a few-layer MoS2 laminate by time-resolved optical pump-terahertz probe spectroscopy[J]. ACS Nano, 2015, 9(12): 12004-12010. doi: 10.1021/acsnano.5b04804
[159] CHEN K, GHOSH R, MENG X H, et al. Experimental evidence of exciton capture by mid-gap defects in CVD grown monolayer MoSe2[J]. npj 2D Materials and Applications, 2017, 1(1): 15. doi: 10.1038/s41699-017-0019-1
[160] CHU ZH D, WANG CH Y, QUAN J M, et al. Unveiling defect-mediated carrier dynamics in monolayer semiconductors by spatiotemporal microwave imaging[J]. Proceedings of the National Academy of Sciences of the United States of America, 2020, 117(25): 13908-13913. doi: 10.1073/pnas.2004106117
[161] HEIN P, STANGE A, HANFF K, et al. Momentum-resolved hot electron dynamics at the 2H-MoS2 surface[J]. Physical Review B, 2016, 94(20): 205406. doi: 10.1103/PhysRevB.94.205406
[162] KASTL C, KOCH R J, CHEN C T, et al. Effects of defects on band structure and excitons in WS2 revealed by nanoscale photoemission spectroscopy[J]. ACS Nano, 2019, 13(2): 1284-1291.
[163] SUN Q, YU H, UENO K, et al. Dissecting the few-femtosecond dephasing time of dipole and quadrupole modes in gold nanoparticles using polarized photoemission electron microscopy[J]. ACS Nano, 2016, 10(3): 3835-3842. doi: 10.1021/acsnano.6b00715
[164] YU H, SUN Q, UENO K, et al. Exploring coupled plasmonic nanostructures in the near field by photoemission electron microscopy[J]. ACS Nano, 2016, 10(11): 10373-10381. doi: 10.1021/acsnano.6b06206
[165] ULSTRUP S, ČABO A G, MIWA J A, et al. Ultrafast band structure control of a two-dimensional heterostructure[J]. ACS Nano, 2016, 10(6): 6315-6322. doi: 10.1021/acsnano.6b02622
[166] ČABO A G, MIWA J A, GRONBORG S S, et al. Observation of ultrafast free carrier dynamics in single layer MoS2[J]. Nano Letters, 2015, 15(9): 5883-5887. doi: 10.1021/acs.nanolett.5b01967
[167] JULIEN M, MICHAEL K. L. M, CHAKRADHAR S, et al. Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors[J]. Science, 2020, 370(6521): 1199-1204. doi: 10.1126/science.aba1029
[168] JOHANNSEN J C, ULSTRUP S, CILENTO F, et al. Direct view of hot carrier dynamics in graphene[J]. Physical Review Letters, 2013, 111(2): 027403. doi: 10.1103/PhysRevLett.111.027403
[169] BERTONI R, NICHOLSON C W, WALDECKER L, et al. Generation and evolution of spin-, valley-, and layer-polarized excited carriers in inversion-symmetric WSe2[J]. Physical Review Letters, 2016, 117(27): 277201. doi: 10.1103/PhysRevLett.117.277201
[170] BEYER H, ROHDE G, ČABO A G, et al. 80% valley polarization of free carriers in singly oriented single-layer WS2 on Au (111)[J]. Physical Review Letters, 2019, 123(23): 236802. doi: 10.1103/PhysRevLett.123.236802
[171] MAN M K L, MARGIOLAKIS A, DECKOFF-JONES S, et al. Imaging the motion of electrons across semiconductor heterojunctions[J]. Nature Nanotechnology, 2017, 12(1): 36-40. doi: 10.1038/nnano.2016.183
[172] LI Y L, SUN Q, ZU SH, et al. Correlation between near-field enhancement and dephasing time in plasmonic dimers[J]. Physical Review Letters, 2020, 124(16): 163901. doi: 10.1103/PhysRevLett.124.163901
[173] WANG L, XU C, LI M Y, et al. Unraveling spatially heterogeneous ultrafast carrier dynamics of single-layer WSe2 by femtosecond time-resolved photoemission electron microscopy[J]. Nano Letters, 2018, 18(8): 5172-5178. doi: 10.1021/acs.nanolett.8b02103
[174] DOHERTY T A S, WINCHESTER A J, MACPHERSON S, et al. Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites[J]. Nature, 2020, 580(7803): 360-366. doi: 10.1038/s41586-020-2184-1
[175] SOBOTA J A, YANG S, ANALYTIS J G, et al. Ultrafast optical excitation of a persistent surface-state population in the topological insulator Bi2Se3[J]. Physical Review Letters, 2012, 108(11): 117403. doi: 10.1103/PhysRevLett.108.117403
[176] GOODMAN A J, LIEN D H, AHN G H, et al. Substrate-dependent exciton diffusion and annihilation in chemically treated MoS2 and WS2[J]. The Journal of Physical Chemistry C, 2020, 124(22): 12175-12184. doi: 10.1021/acs.jpcc.0c04000
[177] KAASBJERG K, MARTINY J H J, LOW T, et al. Symmetry-forbidden intervalley scattering by atomic defects in monolayer transition-metal dichalcogenides[J]. Physical Review B, 2017, 96(24): 241411. doi: 10.1103/PhysRevB.96.241411