Andrea Liscio | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)

Papers by Andrea Liscio

BERAKDAR:CORREL.SPECTROS. O-BK, 2004

Auger-photoelectron coincidence spectroscopy (APECS) has shown that singling out Auger spectra in... more Auger-photoelectron coincidence spectroscopy (APECS) has shown that singling out Auger spectra individual components on the basis of the related photoelectron, i.e., defining the parent core ionic state, increases the energy discrimination capability of both Auger and photoelectron spectroscopy. Angle resolved APECS (AR-APECS) on Ge(100) surface has shown peculiar new features of the electron pair angular distribution with Auger detection angle. It was speculated that these features were to be ascribed to the alignment of the core-hole state induced by selection of the angle of the photoelectron. Recent results on Ge(100) and Cu have drawn attention to the possibility of selecting specific magnetic sublevels of both Auger and photoelectron wavefunctions. Good use of this capability has been made in singling out otherwise overlapping components of both Ge L 3 V V and Cu M 3 V V multiplet split spectra, thus demonstrating that resolution in angle improves discrimination in the energy scale as well.

Four linear terarylene molecules (i) 4-nitro-terphenyl-4′′- methanethiol (NTM), (ii) 4-nitro-terp... more Four linear terarylene molecules (i) 4-nitro-terphenyl-4′′-
methanethiol (NTM), (ii) 4-nitro-terphenyl-3′′,5′′-dimethanethiol (NTD),
(iii) ([1,1′;4′,1′′] terphenyl-3,5-diyl)methanethiol (TM), and (iv) ([1,1′;4′,1′′]
terphenyl-3,5-diyl)dimethanethiol (TD) have been synthesized and their self-
assembled monolayers (SAMs) have been obtained on polycrystalline gold.
NTM and NTD SAMs have been characterized by X-ray photoelectron
spectroscopy, Kelvin probe measurements, electrochemistry, and contact angle
measurements. The terminal nitro group (−NO2) is irreversibly reduced to
hydroxylamine (−NHOH), which can be reversibly turned into nitroso group (−NO). The direct comparison between NTM/ NTD and TM/TD SAMs unambiguously shows the crucial influence of the nitro group on electrowetting properties of polycrystalline Au. The higher grade of surface tension related to NHOH has been successfully exploited for basic operations of digital μ-fluidics, such as droplets motion and merging.

Advanced Energy Materials, 2014

We report a comparative study on the use of four different mesoporous titanium dioxide (TiO 2 ) p... more We report a comparative study on the use of four different mesoporous titanium dioxide (TiO 2 ) photo-electrodes for the fabrication of solid-state dye-sensitized solar cells (sDSSCs). The photovoltaic parameters of the device correlate with several intrinsic properties of the fi lm, based not only on its morphological features, as commonly considered in standard characterizations, but also on the transport and the electronic properties of the photoelectrode. These properties differ signifi cantly for TiO 2 electrodes processed using different colloidal pastes, and are decisive for the photovoltaic effi ciency, ranging from 3.7% up to 5.1%. In particular, the dielectric permittivity of each mesoporous layer ( ε eff ) and the number of traps ( N t ) determined by the spacecharge-limited current (SCLC) theory are found to be a bottle-neck for the charge transport, greatly infl uencing the fi ll factor (FF) and open circuit voltage ( V oc ) of the cells. In addition, a direct correlation between TiO 2 surface potential with the V oc was established. Cross-analysis of key macroscopic parameters of the fi lms prior to integration in the devices, in particular focusing on the determination of the capacitance and surface potential shift of the TiO 2 mesoporous anode, represents a straightforward yet powerful method to screen and select the most suitable TiO 2 for applications in sDSSCs.

Scientific Reports, 2015

Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processabi... more Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processability of polymers, providing a tool to control film quality and material crystallinity. We verify that the employed semiconducting polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), controls the self-assembly of CH 3 NH 3 PbI 3 (MAPbI 3 ) crystalline domains and favors the deposition of a very smooth and homogenous layer in one straightforward step. This idea offers a new paradigm for the implementation of polymer/perovskite nanocomposites towards versatile optoelectronic devices combined with the feasibility of mass production. As a proof-of-concept we propose the application of such nanocomposite in polymer solar cell architecture, demonstrating a power conversion efficiency up to 3%, to date the highest reported for MEH-PPV. On-purpose designed polymers are expected to suit the nanocomposite properties for the integration in diverse optoelectronic devices via facile processing condition.

The Journal of Physical Chemistry C, 2008

We study the influence of different experimental parameters on the interaction between the probe ... more We study the influence of different experimental parameters on the interaction between the probe and the sample in Kelvin probe force microscopy (KPFM) measurements. We provide a precise and reproducible determination of the local surface potential (SP) of clean macroscopic highly oriented pyrolytic graphite (HOPG) samples and of organic semiconducting nanostructures of an alkyl-substituted perylene-bis(dicarboximide) (PDI) self-assembled at surfaces. We distinguish two different terms in the measured SP, intrinsic and extrinsic, containing the electrical properties of the studied object and the experimental artifacts, respectively. We investigate the effect of the most relevant experimental parameters including tip-sample distance, relative humidity (RH), and potential applied to the tip, which govern the extrinsic term of the measured SP. Moreover, we devise a theoretical description of the tip-sample interaction taking into account the extra modulation of the probe due to the applied ac potential during the KPFM scan. A deep understanding of all the terms which contribute to the measured SP in air environment made it possible to devise a new protocol to quantify the electrical properties of nano-objects leading to an improvement of the achieved lateral resolution, as demonstrated by the good agreement between the proposed model and the experimental results.

Physical Review B, 2008

This paper deals with the mechanism of grazing incidence ͑e,2e͒ events from surfaces. Two differe... more This paper deals with the mechanism of grazing incidence ͑e,2e͒ events from surfaces. Two different approaches are considered. In both cases, elastic scattering with the crystal lattice assists the inelastic collision; these two steps are coupled either coherently or incoherently. Experimental evidence is given that the "coherent" approach reproduces better the cross section dependence on momentum transfer in the specific case of asymmetric kinematics at moderate electron energies. This model has allowed us to map out the band dispersion of the outermost valence states of highly oriented pyrolytic graphite and to measure the momentum distribution of -electron states without invoking the contribution of reciprocal lattice vectors in the momentum conservation. Agreement between theory and experiment is satisfactory, though the presence of events where crystal momentum is reconstructed cannot be ruled out. These results, obtained with a significant reduction of the experiment duration by an implemented apparatus, show that reflection ͑e,2e͒ can be used to build up a momentum spectroscopy with high surface sensitivity.

Nanoscale, 2012

This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe... more This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe technique, able to study the photophysics of different structured materials with nanoscale resolution. This tool offers many advantages over standard stationary microscopy techniques because it directly interrogates excited state dynamics in molecules, providing access to both radiative and non-radiative deactivation processes at a local scale. In this paper we present a few different examples of its application to organic semiconductor systems. The first two are focussed on the study of the photophysics of phase-separated polymer blends: (i) a blue-emitting polyfluorene (PFO) in an inert matrix of PMMA and (ii) an electron donor polythiophene (P3HT) mixed with an electron acceptor fullerene derivative (PCBM). The experimental results on these samples demonstrate the capability of the technique to unveil peculiar interfacial dynamics at the border region between phase-segregated domains, which would be otherwise averaged out using conventional pump-probe spectroscopy. The third example is the study of the photophysics of isolated mesoscopic crystals of the PCBM molecule. Our ultrafast microscope could evidence the presence of two distinctive regions within the crystals. In particular, we could pinpoint for the first time areas within the crystals showing photobleaching/stimulated emission signals from a charge-transfer state.

Nanoscale, 2012

We report on the formation of photoconductive self-assembled fibres by solvent induced precipitat... more We report on the formation of photoconductive self-assembled fibres by solvent induced precipitation of a HBC-PMI donor-acceptor dyad. Kelvin Probe Force Microscopy revealed that upon illumination with white light the surface potential of the fibres shifted to negative values due to a build-up of negative charge. When integrated in a field-effect transistor (FET) configuration, the devices can be turned 'on' much more efficiently using light than conventional bias triggered field-effect, suggesting that these structures could be used for the fabrication of light sensing devices. Such a double gating represents an important step towards bi-functional organic FETs, in which the current through the junction can be modulated both optically (by photoexcitation) and electrically (by gate control).

Journal of the American Chemical Society, 2011

Journal of Polymer Science Part B: Polymer Physics, 2012

A prototypical semiconducting bicomponent system consisting of a conjugated polymer, that is, pol... more A prototypical semiconducting bicomponent system consisting of a conjugated polymer, that is, poly(3-hexylthiophene) (P3HT), blended with a small thiophene containing conjugated molecule, that is, an alkyl-substituted bisphenyl-bithiophene [phenylene-thiophene-thiophene-phenylene (PTTP)], has been used as an electroactive active layer in field-effect transistors (FETs). The self-assembly of this bicomponent system at surfaces has been studied at different length scales, from the nanoscale to the macroscale, and compared with the behavior of monocomponent films of PTTP and P3HT. The correlation between morphology and electric properties of the semiconducting material is explored by fabricating prototypes of FETs varying the relative concentrations of the two-component blend. The maximum charge carrier mobility value, achieved with a few percent of PTTP component, is not simply due to a uniform dispersion of the molecules in the polymer matrix, but rather to the generation of very long percolation paths, whose composition and electrical properties can be tuned with the PTTP concentration. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 642-649, 2012

Journal of Materials Chemistry, 2011

Blends of reduced graphene oxide (RGO) and poly(3-hexylthiophene) (P3HT) are used as the active l... more Blends of reduced graphene oxide (RGO) and poly(3-hexylthiophene) (P3HT) are used as the active layer of field-effect transistors (FETs). By using sequential deposition of the two components, the density of RGO sheets can be tuned linearly, thereby modulating their contribution to the charge transport in the transistors, and the onset of charge percolation. The surface potential of RGO, P3HT and source-drain contacts is measured on the nanometric scale with Kelvin Probe Force Microscopy (KPFM), and correlated with the macroscopic performance of the FETs. KPFM is also used to monitor the potential decay along the channel in the working FETs. ; Fax: +33 (0)368 855236; Tel: +33 (0)368 855160 † Electronic supplementary information (ESI) available: Detailed description of i) sample preparation, ii) statistics, iii) used spectroscopic and scanning probe techniques. See

Journal of Electron Spectroscopy and Related Phenomena, 2007

To study electron momentum densities in solids by grazing angle reflection kinematics has been sh... more To study electron momentum densities in solids by grazing angle reflection kinematics has been shown to be feasible [S. Iacobucci, S. Rioual, A. Ruocco, M. Mastropietro, G. Stefani, Surf. Sci. 454 (2000) 1026], but development of this spectroscopy has been hampered by long acquisition time; to fully exploit potentialities of this method is mandatory to reduce duration of the experiment within times comparable with clean surface lifetimes in ultra-high vacuum. This paper reports on recent developments of the reflection (e,2e) spectrometer that make a sizeable step forward in attaining this goal. It operates in asymmetric kinematics and at small grazing angle, thus allowing to enhance the surface sensitivity. A drastic reduction in acquisition time has been achieved by implementing parallel acquisition, both in energy and angle, of the detected electron pairs. To achieve parallel acquisition in energy and momentum, each of the two electron analysers is equipped with a two-dimensional position sensitive detector. A custom-made electronic hardware and software have been developed for the automatic control of the experiment and for acquisition and storage of the coincidence events.

Chemical Communications, 2013

Selective solvent vapour annealing is used on a photovoltaic blend to enhance the interaction bet... more Selective solvent vapour annealing is used on a photovoltaic blend to enhance the interaction between the electron acceptor and the electron donor, simplifying thin films post-processing for photovoltaic applications. A remarkable improvement in the interfacial charge transfer in the bulk hetero-junction is attained, as measured by Kelvin Probe Force Microscopy.

Two main classes of semiconducting molecules are commonly used for opto-electronic applications: ... more Two main classes of semiconducting molecules are commonly used for opto-electronic applications: polymers, featuring an easy solution-processability in thin and uniform yet poorly ordered films, and small poly-aromatic molecules, forming highly defined (liquid)- ...

Accounts of Chemical Research, 2010

Langmuir, 2014

The studies on surface chemical gradients are constantly gaining interest both for fundamental st... more The studies on surface chemical gradients are constantly gaining interest both for fundamental studies and for technological implications in materials science, nanofluidics, dewetting, and biological systems. Here we report on a new approach that is very simple and very efficient, to fabricate surface chemical gradients of alkanethiols, which combines electrochemical desorption/partial readsorption, with the withdrawal of the surface from the solution. The gradient is then stabilized by adding a complementary thiol terminated with a hydroxyl group with a chain length comparable to desorbed thiols. This procedure allows us to fabricate a chemical gradient of the wetting properties and the substrate work-function along a few centimeters with a gradient slope higher than 5°/cm. Samples were characterized by cyclic voltammetry during desorption, static contact angle, XPS analysis, and Kelvin probe. Computer simulations based on the Dissipative Particle Dynamics methods were carried out considering a water droplet on a mixed SAM surface. The results help to rationalize the composition of the chemical gradient at different position on the Au surface.

Time-dependent current density functional theory via time-dependent deformation functional theory... more Time-dependent current density functional theory via time-dependent deformation functional theory: a constrained search formulation in the time domain I. V. Tokatly, Phys. Chem. Chem. Phys.

Advanced Functional Materials, 2011

In the search for new ways to combine the appealing simplicity of solution processing methods and... more In the search for new ways to combine the appealing simplicity of solution processing methods and the need for a high performance of the active layer of organic (opto)electronic devices, the possibilities given by the joint use of well-established casting techniques and post-treatment procedures are explored, as well as new and unconventional deposition protocols to tailor self-assembled architectures with a high degree of order at different length scales, from the subnanometer up to the macroscopic scale. In fact, even the same organic molecule can give rise to different molecular architectures which, in turn, may offer the possibility to exploit a large variety of new functionalities of the deposited materials, paving the way towards the fabrication multifunctional organic-based devices.

BERAKDAR:CORREL.SPECTROS. O-BK, 2004

Auger-photoelectron coincidence spectroscopy (APECS) has shown that singling out Auger spectra in... more Auger-photoelectron coincidence spectroscopy (APECS) has shown that singling out Auger spectra individual components on the basis of the related photoelectron, i.e., defining the parent core ionic state, increases the energy discrimination capability of both Auger and photoelectron spectroscopy. Angle resolved APECS (AR-APECS) on Ge(100) surface has shown peculiar new features of the electron pair angular distribution with Auger detection angle. It was speculated that these features were to be ascribed to the alignment of the core-hole state induced by selection of the angle of the photoelectron. Recent results on Ge(100) and Cu have drawn attention to the possibility of selecting specific magnetic sublevels of both Auger and photoelectron wavefunctions. Good use of this capability has been made in singling out otherwise overlapping components of both Ge L 3 V V and Cu M 3 V V multiplet split spectra, thus demonstrating that resolution in angle improves discrimination in the energy scale as well.

Four linear terarylene molecules (i) 4-nitro-terphenyl-4′′- methanethiol (NTM), (ii) 4-nitro-terp... more Four linear terarylene molecules (i) 4-nitro-terphenyl-4′′-
methanethiol (NTM), (ii) 4-nitro-terphenyl-3′′,5′′-dimethanethiol (NTD),
(iii) ([1,1′;4′,1′′] terphenyl-3,5-diyl)methanethiol (TM), and (iv) ([1,1′;4′,1′′]
terphenyl-3,5-diyl)dimethanethiol (TD) have been synthesized and their self-
assembled monolayers (SAMs) have been obtained on polycrystalline gold.
NTM and NTD SAMs have been characterized by X-ray photoelectron
spectroscopy, Kelvin probe measurements, electrochemistry, and contact angle
measurements. The terminal nitro group (−NO2) is irreversibly reduced to
hydroxylamine (−NHOH), which can be reversibly turned into nitroso group (−NO). The direct comparison between NTM/ NTD and TM/TD SAMs unambiguously shows the crucial influence of the nitro group on electrowetting properties of polycrystalline Au. The higher grade of surface tension related to NHOH has been successfully exploited for basic operations of digital μ-fluidics, such as droplets motion and merging.

Advanced Energy Materials, 2014

We report a comparative study on the use of four different mesoporous titanium dioxide (TiO 2 ) p... more We report a comparative study on the use of four different mesoporous titanium dioxide (TiO 2 ) photo-electrodes for the fabrication of solid-state dye-sensitized solar cells (sDSSCs). The photovoltaic parameters of the device correlate with several intrinsic properties of the fi lm, based not only on its morphological features, as commonly considered in standard characterizations, but also on the transport and the electronic properties of the photoelectrode. These properties differ signifi cantly for TiO 2 electrodes processed using different colloidal pastes, and are decisive for the photovoltaic effi ciency, ranging from 3.7% up to 5.1%. In particular, the dielectric permittivity of each mesoporous layer ( ε eff ) and the number of traps ( N t ) determined by the spacecharge-limited current (SCLC) theory are found to be a bottle-neck for the charge transport, greatly infl uencing the fi ll factor (FF) and open circuit voltage ( V oc ) of the cells. In addition, a direct correlation between TiO 2 surface potential with the V oc was established. Cross-analysis of key macroscopic parameters of the fi lms prior to integration in the devices, in particular focusing on the determination of the capacitance and surface potential shift of the TiO 2 mesoporous anode, represents a straightforward yet powerful method to screen and select the most suitable TiO 2 for applications in sDSSCs.

Scientific Reports, 2015

Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processabi... more Here we conceive an innovative nanocomposite to endow hybrid perovskites with the easy processability of polymers, providing a tool to control film quality and material crystallinity. We verify that the employed semiconducting polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), controls the self-assembly of CH 3 NH 3 PbI 3 (MAPbI 3 ) crystalline domains and favors the deposition of a very smooth and homogenous layer in one straightforward step. This idea offers a new paradigm for the implementation of polymer/perovskite nanocomposites towards versatile optoelectronic devices combined with the feasibility of mass production. As a proof-of-concept we propose the application of such nanocomposite in polymer solar cell architecture, demonstrating a power conversion efficiency up to 3%, to date the highest reported for MEH-PPV. On-purpose designed polymers are expected to suit the nanocomposite properties for the integration in diverse optoelectronic devices via facile processing condition.

The Journal of Physical Chemistry C, 2008

We study the influence of different experimental parameters on the interaction between the probe ... more We study the influence of different experimental parameters on the interaction between the probe and the sample in Kelvin probe force microscopy (KPFM) measurements. We provide a precise and reproducible determination of the local surface potential (SP) of clean macroscopic highly oriented pyrolytic graphite (HOPG) samples and of organic semiconducting nanostructures of an alkyl-substituted perylene-bis(dicarboximide) (PDI) self-assembled at surfaces. We distinguish two different terms in the measured SP, intrinsic and extrinsic, containing the electrical properties of the studied object and the experimental artifacts, respectively. We investigate the effect of the most relevant experimental parameters including tip-sample distance, relative humidity (RH), and potential applied to the tip, which govern the extrinsic term of the measured SP. Moreover, we devise a theoretical description of the tip-sample interaction taking into account the extra modulation of the probe due to the applied ac potential during the KPFM scan. A deep understanding of all the terms which contribute to the measured SP in air environment made it possible to devise a new protocol to quantify the electrical properties of nano-objects leading to an improvement of the achieved lateral resolution, as demonstrated by the good agreement between the proposed model and the experimental results.

Physical Review B, 2008

This paper deals with the mechanism of grazing incidence ͑e,2e͒ events from surfaces. Two differe... more This paper deals with the mechanism of grazing incidence ͑e,2e͒ events from surfaces. Two different approaches are considered. In both cases, elastic scattering with the crystal lattice assists the inelastic collision; these two steps are coupled either coherently or incoherently. Experimental evidence is given that the "coherent" approach reproduces better the cross section dependence on momentum transfer in the specific case of asymmetric kinematics at moderate electron energies. This model has allowed us to map out the band dispersion of the outermost valence states of highly oriented pyrolytic graphite and to measure the momentum distribution of -electron states without invoking the contribution of reciprocal lattice vectors in the momentum conservation. Agreement between theory and experiment is satisfactory, though the presence of events where crystal momentum is reconstructed cannot be ruled out. These results, obtained with a significant reduction of the experiment duration by an implemented apparatus, show that reflection ͑e,2e͒ can be used to build up a momentum spectroscopy with high surface sensitivity.

Nanoscale, 2012

This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe... more This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe technique, able to study the photophysics of different structured materials with nanoscale resolution. This tool offers many advantages over standard stationary microscopy techniques because it directly interrogates excited state dynamics in molecules, providing access to both radiative and non-radiative deactivation processes at a local scale. In this paper we present a few different examples of its application to organic semiconductor systems. The first two are focussed on the study of the photophysics of phase-separated polymer blends: (i) a blue-emitting polyfluorene (PFO) in an inert matrix of PMMA and (ii) an electron donor polythiophene (P3HT) mixed with an electron acceptor fullerene derivative (PCBM). The experimental results on these samples demonstrate the capability of the technique to unveil peculiar interfacial dynamics at the border region between phase-segregated domains, which would be otherwise averaged out using conventional pump-probe spectroscopy. The third example is the study of the photophysics of isolated mesoscopic crystals of the PCBM molecule. Our ultrafast microscope could evidence the presence of two distinctive regions within the crystals. In particular, we could pinpoint for the first time areas within the crystals showing photobleaching/stimulated emission signals from a charge-transfer state.

Nanoscale, 2012

We report on the formation of photoconductive self-assembled fibres by solvent induced precipitat... more We report on the formation of photoconductive self-assembled fibres by solvent induced precipitation of a HBC-PMI donor-acceptor dyad. Kelvin Probe Force Microscopy revealed that upon illumination with white light the surface potential of the fibres shifted to negative values due to a build-up of negative charge. When integrated in a field-effect transistor (FET) configuration, the devices can be turned 'on' much more efficiently using light than conventional bias triggered field-effect, suggesting that these structures could be used for the fabrication of light sensing devices. Such a double gating represents an important step towards bi-functional organic FETs, in which the current through the junction can be modulated both optically (by photoexcitation) and electrically (by gate control).

Journal of the American Chemical Society, 2011

Journal of Polymer Science Part B: Polymer Physics, 2012

A prototypical semiconducting bicomponent system consisting of a conjugated polymer, that is, pol... more A prototypical semiconducting bicomponent system consisting of a conjugated polymer, that is, poly(3-hexylthiophene) (P3HT), blended with a small thiophene containing conjugated molecule, that is, an alkyl-substituted bisphenyl-bithiophene [phenylene-thiophene-thiophene-phenylene (PTTP)], has been used as an electroactive active layer in field-effect transistors (FETs). The self-assembly of this bicomponent system at surfaces has been studied at different length scales, from the nanoscale to the macroscale, and compared with the behavior of monocomponent films of PTTP and P3HT. The correlation between morphology and electric properties of the semiconducting material is explored by fabricating prototypes of FETs varying the relative concentrations of the two-component blend. The maximum charge carrier mobility value, achieved with a few percent of PTTP component, is not simply due to a uniform dispersion of the molecules in the polymer matrix, but rather to the generation of very long percolation paths, whose composition and electrical properties can be tuned with the PTTP concentration. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 642-649, 2012

Journal of Materials Chemistry, 2011

Blends of reduced graphene oxide (RGO) and poly(3-hexylthiophene) (P3HT) are used as the active l... more Blends of reduced graphene oxide (RGO) and poly(3-hexylthiophene) (P3HT) are used as the active layer of field-effect transistors (FETs). By using sequential deposition of the two components, the density of RGO sheets can be tuned linearly, thereby modulating their contribution to the charge transport in the transistors, and the onset of charge percolation. The surface potential of RGO, P3HT and source-drain contacts is measured on the nanometric scale with Kelvin Probe Force Microscopy (KPFM), and correlated with the macroscopic performance of the FETs. KPFM is also used to monitor the potential decay along the channel in the working FETs. ; Fax: +33 (0)368 855236; Tel: +33 (0)368 855160 † Electronic supplementary information (ESI) available: Detailed description of i) sample preparation, ii) statistics, iii) used spectroscopic and scanning probe techniques. See

Journal of Electron Spectroscopy and Related Phenomena, 2007

To study electron momentum densities in solids by grazing angle reflection kinematics has been sh... more To study electron momentum densities in solids by grazing angle reflection kinematics has been shown to be feasible [S. Iacobucci, S. Rioual, A. Ruocco, M. Mastropietro, G. Stefani, Surf. Sci. 454 (2000) 1026], but development of this spectroscopy has been hampered by long acquisition time; to fully exploit potentialities of this method is mandatory to reduce duration of the experiment within times comparable with clean surface lifetimes in ultra-high vacuum. This paper reports on recent developments of the reflection (e,2e) spectrometer that make a sizeable step forward in attaining this goal. It operates in asymmetric kinematics and at small grazing angle, thus allowing to enhance the surface sensitivity. A drastic reduction in acquisition time has been achieved by implementing parallel acquisition, both in energy and angle, of the detected electron pairs. To achieve parallel acquisition in energy and momentum, each of the two electron analysers is equipped with a two-dimensional position sensitive detector. A custom-made electronic hardware and software have been developed for the automatic control of the experiment and for acquisition and storage of the coincidence events.

Chemical Communications, 2013

Selective solvent vapour annealing is used on a photovoltaic blend to enhance the interaction bet... more Selective solvent vapour annealing is used on a photovoltaic blend to enhance the interaction between the electron acceptor and the electron donor, simplifying thin films post-processing for photovoltaic applications. A remarkable improvement in the interfacial charge transfer in the bulk hetero-junction is attained, as measured by Kelvin Probe Force Microscopy.

Two main classes of semiconducting molecules are commonly used for opto-electronic applications: ... more Two main classes of semiconducting molecules are commonly used for opto-electronic applications: polymers, featuring an easy solution-processability in thin and uniform yet poorly ordered films, and small poly-aromatic molecules, forming highly defined (liquid)- ...

Accounts of Chemical Research, 2010

Langmuir, 2014

The studies on surface chemical gradients are constantly gaining interest both for fundamental st... more The studies on surface chemical gradients are constantly gaining interest both for fundamental studies and for technological implications in materials science, nanofluidics, dewetting, and biological systems. Here we report on a new approach that is very simple and very efficient, to fabricate surface chemical gradients of alkanethiols, which combines electrochemical desorption/partial readsorption, with the withdrawal of the surface from the solution. The gradient is then stabilized by adding a complementary thiol terminated with a hydroxyl group with a chain length comparable to desorbed thiols. This procedure allows us to fabricate a chemical gradient of the wetting properties and the substrate work-function along a few centimeters with a gradient slope higher than 5°/cm. Samples were characterized by cyclic voltammetry during desorption, static contact angle, XPS analysis, and Kelvin probe. Computer simulations based on the Dissipative Particle Dynamics methods were carried out considering a water droplet on a mixed SAM surface. The results help to rationalize the composition of the chemical gradient at different position on the Au surface.

Time-dependent current density functional theory via time-dependent deformation functional theory... more Time-dependent current density functional theory via time-dependent deformation functional theory: a constrained search formulation in the time domain I. V. Tokatly, Phys. Chem. Chem. Phys.

Advanced Functional Materials, 2011

In the search for new ways to combine the appealing simplicity of solution processing methods and... more In the search for new ways to combine the appealing simplicity of solution processing methods and the need for a high performance of the active layer of organic (opto)electronic devices, the possibilities given by the joint use of well-established casting techniques and post-treatment procedures are explored, as well as new and unconventional deposition protocols to tailor self-assembled architectures with a high degree of order at different length scales, from the subnanometer up to the macroscopic scale. In fact, even the same organic molecule can give rise to different molecular architectures which, in turn, may offer the possibility to exploit a large variety of new functionalities of the deposited materials, paving the way towards the fabrication multifunctional organic-based devices.