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Molecular-Reductant-Induced Control of a Graphene–Organic Interface for Electron Injection

Author(s): Zhang, Fengyu; Klein, Chen; Longhi, Elena; Barlow, Stephen; Marder, Seth R; et al

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Abstract: Surface doping of graphene with redox-active molecules is an effective approach to tune its electrical properties, in particular for application as transparent electrodes. Here we present a study and application of surface n-doping of graphene with the molecular reductant (pentamethylcyclopentadienyl)(1,3,5-trimethylbenzene)ruthenium dimer ([RuCp*Mes]2). Photoemission spectroscopy and carrier-transport measurements are combined to investigate doping-induced changes in the electronic structure of the interface between graphene and phenyldi(pyren-2-yl)phosphine oxide (POPy2), which is a low-electron-affinity material that has been used as an electron-transport layer (ETL) in organic light-emitting diodes. Photoemission and Hall voltage measurements confirm the n-doping of graphene. Doping with 1−2 nm of [RuCp*Mes]2 reduces the graphene work function by 1.8 eV and the electron injection barrier by more than 1 eV, enhancing electron injection into POPy2 by several orders of magnitude. Graphene/POPy2/Al diodes with doped graphene cathodes exhibit reasonable stability in both nitrogen and air. These results represent a significant step toward the use of graphene as a transparent cathode for organic devices in general and for OLEDs in particular.
Publication Date: 2019
Citation: Zhang, Fengyu, Klein, Chen, Longhi, Elena, Barlow, Stephen, Marder, Seth R, Sarusi, Gabby, Kahn, Antoine. (2019). Molecular-Reductant-Induced Control of a Graphene–Organic Interface for Electron Injection. Chemistry of Materials, 31 (17), 6624 - 6632. doi:10.1021/acs.chemmater.9b00566
DOI: doi:10.1021/acs.chemmater.9b00566
ISSN: 0897-4756
EISSN: 1520-5002
Pages: 6624 - 6632
Language: en
Type of Material: Journal Article
Journal/Proceeding Title: Chemistry of Materials
Version: Author's manuscript

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