Publications de Libero Zuppiroli

Color conversion films comprising polymer-substituted organic fluorescent dyes

Libero Zuppiroli, Rolando Ferrini, Stéphane Suarez, Holger Frauenrath, Roman Niklaus Marty

The present invention concerns a color conversion film comprising at least one active layer, said layer comprising an organic fluorescent dye containing a fluorescent core, wherein said dye is substituted with at least one polymer segment. It also concerns ...

2012

On the origin of exciton formation in dye doped Alq(3) OLEDs

Libero Zuppiroli

Electrically Detected Magnetic Resonance (EDMR) was used to investigate the influence of dye doping on spin-dependent exciton formation in aluminum (III) 8-hydroxyquinoline (Alq(3)) based Organic Light Emitting Diodes (OLEDs) with different device structur ...

Springer2012

Low-loss polymer waveguides on nanoporous layers

Libero Zuppiroli, Rolando Ferrini, Gaëtan Wicht

Multimode planar polymer waveguides were fabricated on hybrid polymer nanoporous layers with a fast industrial aqueous-based method well adapted to coat large-surface plastic substrates and easily scalable up to economical mass production volumes. Using a ...

American Institute of Physics2011

The effects of channel length and film microstructure on the performance of pentacene transistors

Libero Zuppiroli, Jürgen Brugger, Katrin Sidler Arnet, Andreea Veronica Savu, Franziska Dora Fleischli

With the use of the stencil lithography, we fabricated pentacene thin-ﬁlm transistors pre- pared directly on thermally oxidized silicon gates with channel lengths ranging from 2 to 600 lm. By performing 4-probe measurements or by using the transfer line me ...

Elsevier2011

Hopping and trapping mechanisms in organic field-effect transistors

Libero Zuppiroli, Marie-Noëlle Bussac, Steven Konezny

A charge carrier in the channel of an organic field-effect transistor (OFET) is coupled to the electric polarization of the gate in the form of a surface Fröhlich polaron [N. Kirova and M. N. Bussac, Phys. Rev. B 68, 235312 (2003)]. We study the effects of ...

2010

Magnetic field effects on the conductivity of organic bipolar and unipolar devices at room temperature

Frank Nüesch, Libero Zuppiroli

Magnetic field effects on the conductivity of different types of organic devices: undoped and dye doped aluminium (III) 8-hydroxyquinoline (Alq3)-based organic light emitting diodes (OLEDs), electrononly Alq3-based diodes, and a hole-only N,N'-diphenyl-N,N ...

Elsevier2010

From oxide surface to organic transistor properties: the nature and the role of oxide gate surface defects

Libero Zuppiroli, Stéphane Suarez, Franziska Dora Fleischli

By applying various surface treatments to the oxide gate of pentacene transistors, both in vacuum (H2, O2 and Ar plasma treatments) and in aqueous solution, we were able to vary the balance between oxygen-free radicals (Si•), oxygen-centered radicals (Si−O ...

American Chemical Society2010

Organic thin-film transistors: the passivation of the dielectric-pentacene interface by dipolar self-assembled monolayers

Libero Zuppiroli, Stéphane Suarez, Franziska Dora Fleischli

In organic thin-film transistors (OTFTs), the conducting channel is located near the interface between the organic semiconductor and the oxide dielectric; this interface is crucial for transistor performance. Self-assembled monolayers (SAMs) on the interfa ...

American Chemical Society2010

Nanoporous films with low refractive index for large-surface broad-band anti-reflection coatings

Libero Zuppiroli, Rolando Ferrini, Gaëtan Wicht

Nowadays, nanoporous films are widely employed in biochemical applications or in opto-photonic devices such as displays, solar cells, or light-guiding systems. In particular, the technological feasibility of nanoporous layers with low refractive indices ha ...

Wiley-Blackwell2010

Fluorescent nanopigments: Quantitative assessment of their quantum yield

Libero Zuppiroli, Rolando Ferrini

In the last few years, an intense research effort has focused on the synthesis of fluorescent nanopigments for functional inks, light harvesting, tagging, tracing, (bio)labeling, imaging, and lighting applications. Moreover, combined with dielectric matric ...

American Institute of Physics2010

Trap-limited transport in rubrene transistors

Libero Zuppiroli, Marie-Noëlle Bussac, Steven Konezny

The charge carrier mobility in the transport channel of an organic transistor is estimated within the framework of a trap-and-release model. The model accounts for the observed dependence of the mobility on the dielectric constant "epsilon" of the gate ins ...

AIP American Institute of Physics2009

An ester-substituted iridium complex for efficient vacuum-processed organic light-emitting diodes

Philippe Bugnon, Michael Graetzel, Mohammad Khaja Nazeeruddin, Libero Zuppiroli, Rosario Scopelliti, Stéphane Suarez

An orange-red-emitting iridium complex (N958) was prepared, and its photophysical and device-based characteristics were investigated. Despite N958 displaying quite poor photophysical properties in solution (acetonitrile), organic light-emitting diode (OLED ...

2009

Quantum Yield Measurement of Fluorescent Zeolite Nanopigments

Libero Zuppiroli, Rolando Ferrini

Organic fluorescent molecules are infiltrated in the channels of zeolite L nanocrystals, thus creating organic-inorganic fluorescent nanoparticles. Combined with dielectric matrices, these fluorescent nanopigments open the way to the realization of novel o ...

Wiley-Blackwell2009

Local infiltration of planar photonic crystals with UV-curable polymers

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Laurent Balet, Pascale El-Kallassi

We present the local polymer infiltration of planar photonic crystal cavities via a maskless laser-writing technique. After the infiltration of the air holes with a UV-curable monomer a focused laser is used to locally polymerize the monomer in selected ho ...

2008

Controlling charge-transfer at the gate interface of organic field-effect transistors

Libero Zuppiroli, Adrian von Mühlenen, Mauro Castellani

The performance and charge transport characteristics of pentacene transistors with oxide gates such as SiO2 and Al2O3 have been recently shown to largely depend on the density of residual carriers due to electron acceptor defects at the oxide surface. The ...

2008

Charge transport mechanisms in microcrystalline silicon

Libero Zuppiroli, Marie-Noëlle Bussac, Steven Konezny

A heterogeneous charge transport model for microcrystalline silicon based on fluctuation-induced tunneling is presented that fits the low-temperature saturation observed in dark conductivity measurements and accounts for the film microstructure. Excellent ...

AIP American Institute of Physics2008

Sublimation Not an Innocent Technique: A Case of Bis-Cyclometalated Iridium Emitter for OLED

Philippe Bugnon, Michael Graetzel, Mohammad Khaja Nazeeruddin, Libero Zuppiroli, Rosario Scopelliti, Stéphane Suarez

Isomerization of a neutral bis-cyclometalated iridium(III) complex has been observed for the first time during the preparation of vacuum-processed organic light-emitting devices (OLEDs) and reproduced in solution. Isolation of the isomer revealed a cis org ...

2008

Science et technologie comme auxiliaires d'une nouvelle violence

Libero Zuppiroli

Où l’on tente de montrer sur quelques exemples, qu’en déformant la réalité, la « technoscience » contribue à alimenter la logique de guerre économique et de guerre totale, tentation ultime d’un monde dirigé par le marché. Où l’on voit aussi qu’Hannah Arend ...

Editions L'Harmattan2008

Optisches Element und Verfahren zu seiner Herstellung (Optical element and methods for its fabrication)

Libero Zuppiroli, Rolando Ferrini

Applicant: ILFORD Imaging Switzerland GmbH; Designated countries: all; Filing date: September 12, 2008. ...

2008

Local tuning of the optical response of two-dimensional photonic crystals

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Laurent Balet, Pascale El-Kallassi

Local tuning of the optical response of GaAs-based two dimensional photonic crystals (PhCs) is reported. A selective polymer infiltration technique was developed. Scanning electron microscopy and optical measurements were used to characterize the filled Ph ...

Eindhoven University of Technology2008