Microscopic Understanding of Ultrafast Charge Transfer in van der Waals Heterostructures
Journal article, 2021
Van der Waals heterostructures show many intriguing phenomena including ultrafast charge separation following strong excitonic absorption in the visible spectral range. However, despite the enormous potential for future applications in the field of optoelectronics, the underlying microscopic mechanism remains controversial. Here we use time- and angle-resolved photoemission spectroscopy combined with microscopic many-particle theory to reveal the relevant microscopic charge transfer channels in epitaxial WS2/graphene heterostructures. We find that the timescale for efficient ultrafast charge separation in the material is determined by direct tunneling at those points in the Brillouin zone where WS2 and graphene bands cross, while the lifetime of the charge separated transient state is set by defect-assisted tunneling through localized sulphur vacancies. The subtle interplay of intrinsic and defect-related charge transfer channels revealed in the present work can be exploited for the design of highly efficient light harvesting and detecting devices.
Author
R. Krause
University of Regensburg
Max Planck Society
S. Aeschlimann
Max Planck Society
University of Regensburg
M. Chávez-Cervantes
Max Planck Society
Raul Perea Causin
Chalmers, Physics, Condensed Matter and Materials Theory
Samuel Brem
Philipps University Marburg
Ermin Malic
Philipps University Marburg
Chalmers, Physics, Condensed Matter and Materials Theory
Stiven Forti
Center for Nanotechnology Innovation (CNI)
F. Fabbri
Istituto Italiano di Tecnologia
CNR Istituto Nanoscienze, Pisa
Center for Nanotechnology Innovation (CNI)
Camilla Coletti
Center for Nanotechnology Innovation (CNI)
Istituto Italiano di Tecnologia
I. Gierz
University of Regensburg
Physical Review Letters
0031-9007 (ISSN) 1079-7114 (eISSN)
Vol. 127 27 276401Exciton dynamics in atomically thin materials
Swedish Research Council (VR) (2018-00734), 2019-01-01 -- 2024-12-31.
Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1103/PhysRevLett.127.276401
PubMed
35061410