Long-lived charge separation following pump-wavelength-dependent ultrafast charge transfer in graphene/WS2 heterostructures
Fu, Shuai (Max Planck Institute for Polymer Research (Germany))
du Fossé, Indy (Delft University of Technology. Optoelectronic Materials Section (Netherlands))
Jia, Xiaoyu (Max Planck Institute for Polymer Research (Germany))
Xu, Jingyin (University of Electronic Science and Technology of China. Institute of Fundamental and Frontier Sciences (China))
Yu, Xiaoqing (Max Planck Institute for Polymer Research (Germany))
Zhang, Heng (Max Planck Institute for Polymer Research (Germany))
Zheng, Wenhao (Max Planck Institute for Polymer Research (Germany))
Krasel, Sven (Max Planck Institute for Polymer Research (Germany))
Chen, Zongping (Zhejiang University. School of Materials Science and Engineering (China))
Wang, Zhiming M. (University of Electronic Science and Technology of China. Institute of Fundamental and Frontier Sciences (China))
Tielrooij, Klaas-Jan (Institut Català de Nanociència i Nanotecnologia)
Bonn, Mischa (Max Planck Institute for Polymer Research (Germany))
Houtepen, Arjan J. (Delft University of Technology. Optoelectronic Materials Section (Netherlands))
Wang, Hai I. (Max Planck Institute for Polymer Research (Germany))

Fecha:	2021
Resumen:	Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo- thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the perform ance of optoelectronic devices, in particular photodetection.
Ayudas:	European Commission 678004 Ministerio de Economía y Competitividad SEV-2017-0706 European Commission 804349
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Publicado en:	Science advances, Vol. 7, Issue 9 (February 2021) , art. eabd9061, ISSN 2375-2548

DOI: 10.1126/sciadv.abd9061
PMID: 33637529

11 p, 1.4 MB

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