Fig. 18.

Defect-driven properties of 2D materials. a, b Optical images and c, d corresponding fluorescence images of monolayer CVD grown WS. Adapted with permission from Ref. [144]. Copyright 2013, ACS Publications. e Chemical potentials to create point defects elucidated in Fig. 16a, indicate which defects are more likely to occur and f the corresponding schematic of the electronics structural in-gap defect states. Adapted with permission from Ref. [141]. Copyright 2013, ACS Publications. g, h Electrochemical characterisation of various defective MoS₂ compared with Pt and the corresponding electron spin resonance with a higher intensity for samples with less sulphur vacancy defect. Adapted with permission from Ref. [148]. Copyright 2016, ACS Publications. i, j STM image of a twin boundary defect and its STS showing an in-gap state at − 0.94 V. Adapted with permission from Ref. [161]. Copyright ACS Publications. k PL enhancement and l Raman quenching at a 1D crack defect in MoS₂ and m the corresponding spectra. Adapted with permission from Ref. [162]. Copyright 2014, ACS Publications. n Raman intensity of A^′₁(Γ) phonon mode of CVD grown WS₂ monolayers at four different temperatures (T1–T4). Samples are synthesised with increasing defect densities showing distinct Raman intensities and excitonic energy differences. Adapted with permission from Ref. [138]. Copyright 2019, ACS Publications