title: Excitation dependent bidirectional electron transfer in phthalocyanine-functionalised MoS2nanosheets.
abstract: Two-dimensional (2D) transition metal chalcogenides such as 2D MoS2are considered prime candidate materials for the design of next generation optoelectronics. Functionalisation of these materials is considered to be a key step in tailoring their properties towards specific applications and unlocking their full potential. Here we present a van der Waals functionalisation strategy for creating MoS2nanosheets decorated with free base phthalocyanine chromophores. The semiconducting sheets are found to intimately interact with these optoelectronically active chromophores, resulting in an electronic heterostructure that exhibits enhanced optoelectronic properties and exploitable charge transfer. We show that by utilising laterally confined MoS2nanosheets, the conduction band of the semiconductor could be positioned between the chromophore's S1 and S2 states. Consequently, bidirectional photoinduced electron transfer processes are observed, with excitation of the functionalised nanosheet's semiconductor transition resulting in electron transfer to the phthalocyanine's LUMO, and excitation of the chromophore's S2 state leading to electron injection into the MoS2conduction band. However, charge transfer from the dye's S1 transition to the MoS2nanosheet is found to be thermodynamically unfavourable, resulting in intense radiative recombination. These findings may enable controlling and tuning the charge carrier density of semiconducting nanosheets via optical means through the exploitation of photoinduced electron transfer. Furthermore this work provides access to 2D semiconductor-hybrids with tailored absorption profiles and photoluminescence.
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au and Division of Materials Sciences and Engineering, CSIRO, Clayton, Victoria, Australia.
authors.forename: Emily P
authors.initials: EP
authors.lastname: Nguyen
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au and Division of Materials Sciences and Engineering, CSIRO, Clayton, Victoria, Australia.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Carey
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Harrison
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au and Division of Materials Sciences and Engineering, CSIRO, Clayton, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Atkin
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Berean
authors.affiliation: School of Applied Sciences, RMIT University, Melbourne, Victoria, Australia.
authors.forename: Enrico
authors.identifier: http://orcid.org/0000-0001-9948-5893
authors.initials: E
authors.lastname: Della Gaspera
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au.
authors.forename: Jian Zhen
authors.initials: JZ
authors.lastname: Ou
authors.affiliation: Departments of Chemistry and Biochemistry and Materials Science and Engineering, UCLA, Los Angeles, CA, USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Kaner
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au.
authors.forename: Kourosh
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.affiliation: School of Engineering, RMIT University, Melbourne, Victoria, Australia. Emily.Nguyen@csiro.au Kourosh.Kalantar@rmit.edu.au Torben.Daeneke@rmit.edu.au.
authors.forename: Torben
authors.initials: T
authors.lastname: Daeneke