Link between interlayer hybridization and ultrafast charge transfer in WS2 -graphene heterostructures
Journal article, 2023
Ultrafast charge separation after photoexcitation is a common phenomenon in various van-der-Waals (vdW) heterostructures with great relevance for future applications in light harvesting and detection. Theoretical understanding of this phenomenon converges towards a coherent mechanism through charge transfer states accompanied by energy dissipation into strongly coupled phonons. The detailed microscopic pathways are material specific as they sensitively depend on the band structures of the individual layers, the relative band alignment in the heterostructure, the twist angle between the layers, and interlayer interactions resulting in hybridization. We used time- and angle-resolved photoemission spectroscopy combined with tight binding and density functional theory electronic structure calculations to investigate ultrafast charge separation and recombination in WS2-graphene vdW heterostructures. We identify several avoided crossings in the band structure and discuss their relevance for ultrafast charge transfer. We relate our own observations to existing theoretical models and propose a unified picture for ultrafast charge transfer in vdW heterostructures where band alignment and twist angle emerge as the most important control parameters.
tight binding band structure calculations
time- and angle-resolved photoemission spectroscopy
ultrafast charge transfer
van-der-Waals heterostructures
density functional theory
Author
Niklas Hofmann
University of Regensburg
Leonard Weigl
University of Regensburg
Johannes Gradl
University of Regensburg
Neeraj Mishra
Center for Nanotechnology Innovation (CNI)
Istituto Italiano di Tecnologia
Giorgio Orlandini
Center for Nanotechnology Innovation (CNI)
Stiven Forti
Center for Nanotechnology Innovation (CNI)
Camilla Coletti
Center for Nanotechnology Innovation (CNI)
Istituto Italiano di Tecnologia
Simone Latini
Technical University of Denmark (DTU)
Lede Xian
Songshan Lake Materials Laboratory
Angel Rubio
Max Planck Society
Dilan Perez Paredes
Philipps University Marburg
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
I. Gierz
University of Regensburg
2D Materials
2053-1583 (eISSN)
Vol. 10 3 035025Subject Categories
Infrastructure Engineering
Condensed Matter Physics
DOI
10.1088/2053-1583/acdaab