Premium
Photodriven Transient Picosecond Top‐Layer Semiconductor to Metal Phase‐Transition in p‐Doped Molybdenum Disulfide
Author(s) -
Sorgenfrei Nomi L. A. N.,
Giangrisostomi Erika,
Jay Raphael M.,
Kühn Danilo,
Neppl Stefan,
Ovsyannikov Ruslan,
Sezen Hikmet,
Svensson Svante,
Föhlisch Alexander
Publication year - 2021
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202006957
Subject(s) - materials science , molybdenum disulfide , semiconductor , doping , band gap , optoelectronics , surface states , electron , photocatalysis , picosecond , laser , optics , chemistry , biochemistry , geometry , mathematics , physics , quantum mechanics , surface (topology) , metallurgy , catalysis
Visible light is shown to create a transient metallic S–Mo–S surface layer on bulk semiconducting p‐doped indirect‐bandgap 2H‐MoS 2 . 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‐MoS 2 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‐MoS 2 . 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‐MoS 2 . Generally, it opens up for a way to control not only the surface of p‐doped 2H‐MoS 2 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.