title: Achieving Ultrafast Hole Transfer at the Monolayer MoS2 and CH3NH3PbI3 Perovskite Interface by Defect Engineering.
abstract: The performance of a photovoltaic device is strongly dependent on the light harvesting properties of the absorber layer as well as the charge separation at the donor/acceptor interfaces. Atomically thin two-dimensional transition metal dichalcogenides (2-D TMDCs) exhibit strong light-matter interaction, large optical conductivity, and high electron mobility; thus they can be highly promising materials for next-generation ultrathin solar cells and optoelectronics. However, the short optical absorption path inherent in such atomically thin layers limits practical applications. A heterostructure geometry comprising 2-D TMDCs (e.g., MoS2) and a strongly absorbing material with long electron-hole diffusion lengths such as methylammonium lead halide perovskites (CH3NH3PbI3) may overcome this constraint to some extent, provided the charge transfer at the heterostructure interface is not hampered by their band offsets. Herein, we demonstrate that the intrinsic band offset at the CH3NH3PbI3/MoS2 interface can be overcome by creating sulfur vacancies in MoS2 using a mild plasma treatment; ultrafast hole transfer from CH3NH3PbI3 to MoS2 occurs within 320 fs with 83% efficiency following photoexcitation. Importantly, our work highlights the feasibility of applying defect-engineered 2-D TMDCs as charge-extraction layers in perovskite-based optoelectronic devices.
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.|National Engineering Research Center of Electromagnetic Radiation Control Materials and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Peng
authors.affiliation: School of Physical & Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Guannan
authors.initials: G
authors.lastname: Yu
authors.affiliation: China Academy of Engineering Physics , P.O. Box 919-71, Mianyang, 621900, Sichuan, China.
authors.forename: Yawen
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Physical & Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: School of Physical & Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Guichuan
authors.initials: G
authors.lastname: Xing
authors.affiliation: School of Physical & Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.|CAS Center for Excellence in Nanoscience & CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology , Beijing 100190, China.
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Deyi
authors.initials: D
authors.lastname: Fu
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Jun Rong Sherman
authors.initials: JR
authors.lastname: Tan
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.affiliation: National Engineering Research Center of Electromagnetic Radiation Control Materials and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Haipeng
authors.initials: H
authors.lastname: Lu
authors.affiliation: National Engineering Research Center of Electromagnetic Radiation Control Materials and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Jianliang
authors.initials: J
authors.lastname: Xie
authors.affiliation: National Engineering Research Center of Electromagnetic Radiation Control Materials and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Longjiang
authors.initials: L
authors.lastname: Deng
authors.affiliation: School of Physical & Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Tze Chien
authors.initials: TC
authors.lastname: Sum
authors.affiliation: Department of Chemistry and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Kian Ping
authors.initials: KP
authors.lastname: Loh
keywords: S vacancies; charge transfer; heterojunction; perovskite; two-dimensional transition metal dichalcogenides