Free Trions with Near-Unity Quantum Yield in Monolayer MoSe2.

Trions, quasiparticles composed of an electron-hole pair bound to a second electron and/or hole, are many-body states with potential applications in optoelectronics. Trions in monolayer transition metal dichalcogenide (TMD) semiconductors have attracted recent interest due to their valley/spin polarization, strong binding energy, and tunability through external gate control. However, low materials quality (i.e., high defect density) has hindered efforts to understand the intrinsic properties of trions. The low photoluminescence (PL) quantum yield (QY) and short lifetime of trions have prevented harnessing them in device applications. Here, we study the behavior of trions in a series of MoSe2 monolayers, with atomic defect density varying by over 2 orders of magnitude. The QY increases with decreasing defect density and approaches unity in the cleanest material. Simultaneous measurement of the PL lifetime yields both the intrinsic radiative lifetime and the defect-dependent nonradiative lifetime. The long lifetime of ∼230 ps of trions allows direct observation of their diffusion.

[1]  P. Kim,et al.  Strongly adhesive dry transfer technique for van der Waals heterostructure , 2020, 2D Materials.

[2]  C. Robert,et al.  Filtering the photoluminescence spectra of atomically thin semiconductors with graphene , 2019, Nature Nanotechnology.

[3]  L. Balicas,et al.  Approaching the Intrinsic Limit in Transition Metal Diselenides via Point Defect Control. , 2019, Nano letters.

[4]  E. Yablonovitch,et al.  Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors , 2019, Science.

[5]  A. Javey,et al.  Synthetic WSe2 monolayers with high photoluminescence quantum yield , 2019, Science Advances.

[6]  Kenji Watanabe,et al.  Electroluminescence from multi-particle exciton complexes in transition metal dichalcogenide semiconductors , 2018, Nature Communications.

[7]  Ziliang Ye,et al.  Efficient generation of neutral and charged biexcitons in encapsulated WSe2 monolayers , 2018, Nature Communications.

[8]  D. Smirnov,et al.  Revealing the biexciton and trion-exciton complexes in BN encapsulated WSe2 , 2018, Nature Communications.

[9]  M. Atatüre,et al.  Charge-tuneable biexciton complexes in monolayer WSe2 , 2018, Nature Communications.

[10]  A. Krasheninnikov,et al.  Post-Synthesis Modifications of Two-Dimensional MoSe2 or MoTe2 by Incorporation of Excess Metal Atoms into the Crystal Structure. , 2018, ACS nano.

[11]  Kenji Watanabe,et al.  Coulomb-bound four- and five-particle intervalley states in an atomically-thin semiconductor , 2018, Nature Communications.

[12]  A. C. H. Rowe,et al.  Exciton diffusion in WSe2 monolayers embedded in a van der Waals heterostructure , 2018, 1802.09201.

[13]  K. Loh,et al.  Whisper Gallery Modes in Monolayer Tungsten Disulfide-Hexagonal Boron Nitride Optical Cavity , 2017 .

[14]  J. Hone,et al.  Trion-Species-Resolved Quantum Beats in MoSe2. , 2017, ACS nano.

[15]  H. Tan,et al.  Excited State Biexcitons in Atomically Thin MoSe2. , 2017, ACS nano.

[16]  Kenji Watanabe,et al.  Approaching the intrinsic photoluminescence linewidth in transition metal dichalcogenide monolayers , 2017, 1702.05857.

[17]  M. Lukin,et al.  Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons. , 2017, Nature nanotechnology.

[18]  Judith F. Specht,et al.  Neutral and charged inter-valley biexcitons in monolayer MoSe2 , 2016, Nature Communications.

[19]  T. Kaneko,et al.  Transport Dynamics of Neutral Excitons and Trions in Monolayer WS2. , 2016, ACS nano.

[20]  Tobias Korn,et al.  Coherent and Incoherent Coupling Dynamics between Neutral and Charged Excitons in Monolayer MoSe2. , 2016, Nano letters.

[21]  Eugene Demler,et al.  Fermi polaron-polaritons in charge-tunable atomically thin semiconductors , 2016, Nature Physics.

[22]  E. Yablonovitch,et al.  Near-unity photoluminescence quantum yield in MoS2 , 2015, Science.

[23]  Timothy C. Berkelbach,et al.  Observation of biexcitons in monolayer WSe2 , 2015, Nature Physics.

[24]  J. Grossman,et al.  Exciton radiative lifetimes in two-dimensional transition metal dichalcogenides. , 2015, Nano letters.

[25]  Xiaodong Xu,et al.  Valley excitons in two-dimensional semiconductors , 2015, 1507.08103.

[26]  Junsong Yuan,et al.  Exploring atomic defects in molybdenum disulphide monolayers , 2015, Nature Communications.

[27]  E. Palleau,et al.  Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers , 2015, 1502.03591.

[28]  A Gholinia,et al.  Light-emitting diodes by band-structure engineering in van der Waals heterostructures. , 2014, Nature materials.

[29]  K. L. Shepard,et al.  One-Dimensional Electrical Contact to a Two-Dimensional Material , 2013, Science.

[30]  K. Novoselov,et al.  Strong Light-Matter Interactions in Heterostructures of Atomically Thin Films , 2013, Science.

[31]  Aaron M. Jones,et al.  Electrical control of neutral and charged excitons in a monolayer semiconductor , 2012, Nature Communications.

[32]  J. Shan,et al.  Tightly bound trions in monolayer MoS2. , 2012, Nature materials.

[33]  K. Shepard,et al.  Boron nitride substrates for high-quality graphene electronics. , 2010, Nature nanotechnology.

[34]  D. Ritchie,et al.  Observation of Charge Transport by Negatively Charged Excitons , 2001, Science.