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Libero Zuppiroli

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Related publications (49)

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

Rolando Ferrini, Libero Zuppiroli, 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

Synthesis of novel cyanine-fullerene dyads for photovoltaic devices

Frank Nüesch, Libero Zuppiroli

Two novel cyanine-fullerene dyads have been synthesized by means of the Prato reaction from the corresponding cyanine-aldehyde, N-methylglycine and C60. As well as a thorough characterization using MS-TOF, 1H-NMR, 13C-NMR a ...

Royal Society of Chemistry2005

Charge transport across organic-organic interfaces in organic light-emitting diodes

Libero Zuppiroli, Hocine Houili

The process of hopping transport across organic heterojunctions is critical to the function of organic light-emitting diodes (OLED) and many other currently developed organic electronic devices. We consider the case of a hole-only or homopolar heterojuncti ...

Elsevier2006

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

Jürgen Brugger, Andreea Veronica Savu, Libero Zuppiroli, Katrin Sidler Arnet, Michel Schär, 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

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

Libero Zuppiroli, Michel Schär, Mauro Castellani, Adrian von Mühlenen

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

Planar photonic crystals infiltrated with liquid crystals: optical characterization of molecule orientation

Romuald Houdré, Rolando Ferrini, Libero Zuppiroli, Liza Carol Andrea Dunbar, Barbara Wild, Vasily Zabelin

Nematic liquid crystals are infiltrated into InP-based planar photonic crystals. Optical measurements as a function of temperature and polarization are used to study the average director field configuration in the nanometer-size holes: a planar equilibrium ...

Opt. Soc. America2006

Tuneable planar photonic crystals

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Liza Carol Andrea Dunbar, Barbara Wild

2005

Local infiltration of planar photonic crystals with UV-curable polymers

Romuald Houdré, Rolando Ferrini, Libero Zuppiroli, 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

Tuneable planar photonic crystal devices

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Liza Carol Andrea Dunbar, Barbara Wild

2005

Polarization effects in the channel of an organic field-effect transistor

Libero Zuppiroli, Marie-Noëlle Bussac, Jean-David Picon, Hocine Houili

We present the results of our calculation of the effects of dynamical coupling of a charge carrier to the electronic polarization and the field-induced lattice displacements at the gate interface of an organic field-effect transistor (OFET). We find that t ...

American Institute of Physics Inc.2006

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

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

Counterion effects in cyanine heterojunction photovoltaic devices

Frank Nüesch, Libero Zuppiroli, Antonin Faes

We investigated cyanine heterojunction photovoltaic devices using carbocyanine dyes as donors and buckminsterfullerene (C60) as acceptor. In particular, we focused on the influence of cyanine counterions on the photovoltaic device characteristics. It was f ...

2005

Charge transport mechanisms in microcrystalline silicon

Libero Zuppiroli, Marie-Noëlle Bussac

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

Optical tuning of planar photonic crystals infiltrated with organic molecules

Romuald Houdré, Rolando Ferrini, Libero Zuppiroli, Nicolas Le Thomas, Pascale El-Kallassi

The optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photo-responsive liquid crystal system is presented. Photo-induced phase transitions of a liquid crystal blend doped with azobenzene molecules are used to tune the optical r ...

2007

Cubic and oriented Ag nano-particles by high vacuum evaporation

Libero Zuppiroli, Detlef Berner

Ag cubes of uniform size (70nm) and self-assembled into two dimensional arrays are formed by physical vapor deposition. The formation of the Ag cubes depends critically on the substrate composition. While heat dissipation can control the crystallization of ...

Nano Science and Technology Institute, Cambridge, MA 02139, United States2006

Planar photonic crystals infiltrated with liquid crystals: tuning of the optical properties

Romuald Houdré, Libero Zuppiroli, Rolando Ferrini, Liza Carol Andrea Dunbar, Nicolas Le Thomas

2006

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

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

Low-loss polymer waveguides on nanoporous layers

Rolando Ferrini, Libero Zuppiroli, 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

Color conversion films comprising polymer-substituted organic fluorescent dyes

Libero Zuppiroli, Rolando Ferrini, Holger Frauenrath, Stéphane Suarez, 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

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

Libero Zuppiroli, Stéphane Suarez, Michel Schär, 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