@article{SorgenfreiGiangrisostomiJayetal.2021,
  author    = {Sorgenfrei, Nomi and Giangrisostomi, Erika and Jay, Raphael Martin and K{\"u}hn, Danilo and Neppl, Stefan and Ovsyannikov, Ruslan and Sezen, Hikmet and Svensson, Svante and F{\"o}hlisch, Alexander},
  title     = {Photodriven transient picosecond top-layer semiconductor to metal phase-transition in p-doped molybdenum disulfide},
  series = {Advanced materials},
  volume    = {33},
  journal   = {Advanced materials},
  number    = {14},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0935-9648},
  doi       = {10.1002/adma.202006957},
  pages     = {8},
  year      = {2021},
  abstract  = {Visible light is shown to create a transient metallic S-Mo-S surface layer on bulk semiconducting p-doped indirect-bandgap 2H-MoS2. Optically created electron-hole pairs separate in the surface band bending region of the p-doped semiconducting crystal causing a transient accumulation of electrons in the surface region. This triggers a reversible 2H-semiconductor to 1T-metal phase-transition of the surface layer. Electron-phonon coupling of the indirect-bandgap p-doped 2H-MoS2 enables this efficient pathway even at a low density of excited electrons with a distinct optical excitation threshold and saturation behavior. This mechanism needs to be taken into consideration when describing the surface properties of illuminated p-doped 2H-MoS2. In particular, light-induced increased charge mobility and surface activation can cause and enhance the photocatalytic and photoassisted electrochemical hydrogen evolution reaction of water on 2H-MoS2. Generally, it opens up for a way to control not only the surface of p-doped 2H-MoS2 but also related dichalcogenides and layered systems. The findings are based on the sensitivity of time-resolved electron spectroscopy for chemical analysis with photon-energy-tuneable synchrotron radiation.},
  language  = {en}
}