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ACS Nano. 2019 Apr 23;13(4):4183-4190. doi: 10.1021/acsnano.8b09166. Epub 2019 Mar 20.

Electronic Coupling in Metallophthalocyanine-Transition Metal Dichalcogenide Mixed-Dimensional Heterojunctions.

Author information

1
Department of Chemistry and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States.
2
Center for Light Energy Activated Redox Processes , Evanston , Illinois 60208 , United States.
3
Department of Physics and Astronomy , Northwestern University , Evanston , Illinois 60208 , United States.
4
Department of Materials Science and Engineering and the Materials Research Center , Northwestern University , Evanston , Illinois 60208 , United States.
5
Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States.
6
Northwestern Argonne Institute for Science and Engineering , Evanston , Illinois 60208 , United States.

Abstract

Mixed-dimensional heterojunctions, such as zero-dimensional (0D) organic molecules deposited on two-dimensional (2D) transition metal dichalcogenides (TMDCs), often exhibit interfacial effects that enhance the properties of the individual constituent layers. Here we report a systematic study of interfacial charge transfer in metallophthalocyanine (MPc) - MoS2 heterojunctions using optical absorption and Raman spectroscopy to elucidate M core (M = first row transition metal), MoS2 layer number, and excitation wavelength effects. Observed phenomena include the emergence of heterojunction-specific optical absorption transitions and strong Raman enhancement that depends on the M identity. In addition, the Raman enhancement is tunable by excitation laser wavelength and MoS2 layer number, ultimately reaching a maximum enhancement factor of 30x relative to SiO2 substrates. These experimental results, combined with density functional theory (DFT) calculations, indicate strong coupling between nonfrontier MPc orbitals and the MoS2 band structure as well as charge transfer across the heterojunction interface that varies as a function of the MPc electronic structure.

KEYWORDS:

charge transfer; heterojunction; metallophthalocyanine; phthalocyanine; transition metal dichalcogenide

PMID:
30848891
DOI:
10.1021/acsnano.8b09166

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