Self-assembly of bicomponent molecular monolayers: adsorption height changes and their consequences.
Codeposition of two molecular species [copper phtalocyanine (CuPc, donor) and perfluoropentacene (PFP, acceptor)] on noble metal (111) surfaces leads to the self-assembly of an ordered mixed layer with a maximized donor-acceptor contact area. The main driving force behind this arrangement is assumed to be the intermolecular C-H ⋯ F hydrogen-bond interactions. Such interactions would be maximized for a coplanar molecular arrangement. However, precise measurement of molecule-substrate distances in the molecular mixture reveals significantly larger adsorption heights for PFP than for CuPc. Most surprisingly, instead of leveling to increase hydrogen-bond interactions, the height difference is enhanced in the blends as compared to the heights found in single-component CuPc and PFP layers. The increased height of PFP in mixed layers points to an overall reduced interaction with the underlying substrate, and its influence on electronic properties like the interface dipole is investigated through work function measurements.
Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 San Sebastián, Spain.
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Goiri
Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 San Sebastián, Spain.
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Matena
Departamento Física Aplicada I, Universidad del País Vasco, 20018 San Sebastián, Spain.
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El-Sayed
Centro de Física de Materiales (CSIC/UPV-EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
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Lobo-Checa
Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 San Sebastián, Spain and Centro de Física de Materiales (CSIC/UPV-EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
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Borghetti
Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 San Sebastián, Spain and Centro de Física de Materiales (CSIC/UPV-EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
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Rogero
European Synchrotron Radiation Facility, BP 220, 6 rue Jules Horowitz, 38043 Grenoble, France.
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Detlefs
European Synchrotron Radiation Facility, BP 220, 6 rue Jules Horowitz, 38043 Grenoble, France.
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Duvernay
Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 San Sebastián, Spain and Departamento Física Aplicada I, Universidad del País Vasco, 20018 San Sebastián, Spain and Centro de Física de Materiales (CSIC/UPV-EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
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Ortega
Centro de Física de Materiales (CSIC/UPV-EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain.
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de Oteyza