Figure 6.

2D material‐based light emitters. a) Suspended graphene for enhanced photon emission at visible regime. Reproduced with permission.^{[ 83 ]} Copyright 2015, Nature Publishing Group. b) Mid‐infrared black phosphorus emitter under the excitation of 640 nm. Reproduced with permission.^{[ 90 ]} Copyright 2020, American Association for the Advancement of Science. c) Valley transition in a MoS₂ monolayer in the presence of the magnetic field. Reproduced with permission.^{[ 87 ]} Copyright 2017, American Physical Society. d) Photoluminescence wavelengths shifted by the excitation wavelengths (left‐up), Reproduced with permission.^{[ 95 ]} Copyright 2018, Royal Society of Chemistry, the PL lifetime of MXene QDs at different pH values (left‐down) Reproduced with permission.^{[ 96 ]} Copyright 2018, Royal Society of Chemistry, and the emerging of the random laser as the increase of pump power (right), Reproduced with permission.^{[ 92 ]} Copyright 2019, Wiley‐VCH.