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Dive into the research topics where Silvia Rosselli is active.

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Featured researches published by Silvia Rosselli.


ACS Nano | 2014

Organic Dipole Layers for Ultralow Work Function Electrodes

William E. Ford; Deqing Gao; Nikolaus Knorr; Rene Wirtz; Frank Scholz; Zoi Karipidou; Kodo Ogasawara; Silvia Rosselli; Vadim Rodin; Gabriele Nelles; Florian von Wrochem

The alignment of the electrode Fermi level with the valence or conduction bands of organic semiconductors is a key parameter controlling the efficiency of organic light-emitting diodes, solar cells, and printed circuits. Here, we introduce a class of organic molecules that form highly robust dipole layers, capable of shifting the work function of noble metals (Au and Ag) down to 3.1 eV, that is, ∼1 eV lower than previously reported self-assembled monolayers. The physics behind the considerable interface dipole is elucidated by means of photoemission spectroscopy and density functional theory calculations, and a polymer diode exclusively based on the surface modification of a single electrode in a symmetric, two-terminal Au/poly(3-hexylthiophene)/Au junction is presented. The diode exhibits the remarkable rectification ratio of ∼2·10(3), showing high reproducibility, durability (>3 years), and excellent electrical stability. With this evidence, noble metal electrodes with work function values comparable to that of standard cathode materials used in optoelectronic applications are demonstrated.


Journal of Applied Physics | 2010

Surface-potential decay of biased-probe contact-charged amorphous polymer films

Nikolaus Knorr; Silvia Rosselli; Gabriele Nelles

We have investigated the decay of scanning Kelvin probe force microscopy (KPFM) and electric force microscopy (EFM) signals from biased-probe contact-charged films of three different amorphous polymers representing wide-ranging water absorption capabilities. The surface-potential decay (SPD) has been measured by repeatedly scanning the charge pattern as a function of dissipation time t while varying the relative humidity (RH), the film thickness d, the temperature, the charging voltage, and the load on the scanning probe. Whereas increases in KPFM and EFM peak widths are appreciable only in the long run, the decay in the peak heights is rapid at the beginning and then strongly slowing down with time. Peak heights can be approximated for t<1 hour by power laws of negative exponents (−β), with 0<β<0.5 in dry conditions. β increases for thinner films and when scanning with higher probe loads. Raising the humidity or heating to temperatures well below the glass transition temperature of the polymer considerab...


Journal of Applied Physics | 2009

Biased-probe-induced water ion injection into amorphous polymers investigated by electric force microscopy

Nikolaus Knorr; Silvia Rosselli; Tzenka Miteva; Gabriele Nelles

Although charging of insulators by atomic force microscopy (AFM) has found widespread interest, often with data storage or nanoxerography in mind, less attention has been paid to the charging mechanism and the nature of the charge. Here we present a systematic study on charging of amorphous polymer films by voltage pulses applied to conducting AFM probes. We find a quadratic space charge limited current law of Kelvin probe force microscopy and electrostatic force microscopy peak volumes in pulse height, offset by a threshold voltage, and a power law in pulse width of positive exponents smaller than one. We interpret the results by a charging mechanism of injection and surface near accumulation of aqueous ions stemming from field induced water adsorption, with threshold voltages linked to the water affinities of the polymers.


Journal of Applied Physics | 2013

Evidence of electrochemical resistive switching in the hydrated alumina layers of Cu/CuTCNQ/(native AlOx)/Al junctions

Nikolaus Knorr; Ameneh Bamedi; Zoi Karipidou; Rene Wirtz; Mustafa Sarpasan; Silvia Rosselli; Gabriele Nelles

We have investigated bipolar resistive switching of Cu/CuTCNQ/Al cross-junctions in both vacuum and different gas environments. While the generally observed S-shaped I-V hysteresis was reproduced in ambient air, it was reversibly suppressed in well-degassed samples in vacuum and in dry N2. The OFF-switching currents in ambient air peaked when approximately +2.6 V was applied to the Al electrode at low voltage sweep rates. OFF-switching at constant bias was accelerated in humid and oxygen-rich atmospheres. For unbiased samples stored in air, ON-state (RON) and OFF-state (ROFF) resistances increased with time, and RON surpassed the initial ROFF after approximately one week. Retention times were enhanced for samples stored in vacuum and those with a larger cross-junction area. We suggest that resistive switching occurs in a hydrated native alumina layer at the CuTCNQ/Al interface that grows in thickness during exposure to ambient humidity: ON-switching by electrochemical metallization of free Al and/or Cu io...


Advanced Materials | 2016

Ultrarobust Thin-Film Devices from Self-Assembled Metal-Terpyridine Oligomers

Zoi Karipidou; Barbara Branchi; Mustafa Sarpasan; Nikolaus Knorr; Vadim Rodin; Pascal Friederich; Tobias Neumann; Velimir Meded; Silvia Rosselli; Gabriele Nelles; Wolfgang Wenzel; Maria Anita Rampi; Florian von Wrochem

Ultrathin molecular layers of Fe(II) -terpyridine oligomers allow the fabrication of large-area crossbar junctions by conventional electrode vapor deposition. The junctions are electrically stable for over 2.5 years and operate over a wide range of temperatures (150-360 K) and voltages (±3 V) due to the high cohesive energy and packing density of the oligomer layer. Electrical measurements reveal ideal Richardson-Shottky emission in surprising agreement with electrochemical, optical, and photoemission data.


Nature Materials | 2005

Low-temperature fabrication of dye-sensitized solar cells by transfer of composite porous layers

Michael Dürr; Andreas K. Schmid; Markus Obermaier; Silvia Rosselli; Akio Yasuda; Gabriele Nelles


Synthetic Metals | 2005

Photogeneration and photovoltaic effect in blends of derivatives of hexabenzocoronene and perylene

Jaroslaw Jung; Andrzej Rybak; Agnieszka Slazak; Slawomir Bialecki; Pawel Miskiewicz; Ireneusz Glowacki; Jacek Ulanski; Silvia Rosselli; Akio Yasuda; Gabriele Nelles; Zeljko Tomovic; Mark D. Watson; Klaus Müllen


Macromolecular Materials and Engineering | 2008

High‐Molecular‐Weight Polyoxirane Copolymers and their Use in High‐Performance Dye‐Sensitized Solar Cells

Petar Petrov; Iliyana V. Berlinova; Christo B. Tsvetanov; Silvia Rosselli; Andreas K. Schmid; Ameneh Bamedi Zilaei; Tzenka Miteva; Michael Dürr; Akio Yasuda; Gabriele Nelles


Journal of Physical Chemistry C | 2010

Field-Absorbed Water Induced Electrochemical Processes in Organic Thin Film Junctions

Nikolaus Knorr; Rene Wirtz; Silvia Rosselli; Gabriele Nelles


Archive | 2008

Preparation of high-quality sensitizer dye for dye-sensitized solar cells

Zilai Ameneh Bamedi; Gerda Fuhrmann; Gabriele Nelles; Markus Obermaier; Silvia Rosselli

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Christo B. Tsvetanov

Bulgarian Academy of Sciences

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Iliyana V. Berlinova

Bulgarian Academy of Sciences

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Rayna Stamenova

Bulgarian Academy of Sciences

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Petar Petrov

Bulgarian Academy of Sciences

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William E. Ford

Bowling Green State University

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Dirk Mayer

Forschungszentrum Jülich

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Nils Sanetra

Forschungszentrum Jülich

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