There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3

Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles

Organic solar cell research has developed during the past 30 years, but especially in the last decade it has attracted scientific and economic interest triggered by a rapid increase in power conversion efficiencies. This was achieved by the introduction of new materials, improved materials engineering, and more sophisticated device structures. Today, solar power conversion efficiencies in excess of 3% have been accomplished with several device concepts. Though efficiencies of these thin-film organicdevices have not yet reached those of their inorganic counterparts (η ≈ 10–20%); the perspective of cheap production (employing, e.g., roll-to-roll processes) drives the development of organic photovoltaic devices further in a dynamic way. The two competitive production techniques used today are either wet solution processing or dry thermal evaporation of the organic constituents. The field of organic solar cells profited well from the development of light-emitting diodes based on similar technologies, which have entered the market recently. We review here the current status of the field of organic solar cells and discuss different production technologies as well as study the important parameters to improve their performance.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400094498

Organic solar cells: An overview

Functionalized acenes and heteroacenes for organic electronics.

Raman spectroscopy is a standard characterization technique for any carbon system. Here we review the Raman spectra of amorphous, nanostructured, diamond-like carbon and nanodiamond. We show how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen. The measured spectra change with varying excitation energy. By visible and ultraviolet excitation measurements, the G peak dispersion can be derived and correlated with key parameters, such as density, sp(3) content, elastic constants and chemical composition. We then discuss the assignment of the peaks at 1150 and 1480 cm(-1) often observed in nanodiamond. We review the resonant Raman, isotope substitution and annealing experiments, which lead to the assignment of these peaks to trans-polyacetylene.

Raman spectroscopy of amorphous, nanostructured, diamond-like carbon, and nanodiamond

Pentacene stands out as a model molecule among organic semiconductors due to its ability to form well-ordered films that show a high field effect mobility. We discuss the processes involved in pentacene film growth, emphasizing differences with respect to inorganic films. The influence of growth parameters such as the substrate nature and temperature, the deposition rate, and the kinetic energy of the molecular beam on the structure and morphology of pentacene films are discussed. Finally, we overview recent attempts to model pentacene film nucleation and growth, and draw attention to the role of dislocations.

Pentacene Thin Film Growth

1. Introduction.- 2. Molecular Beams and Cluster Nucleation.- 2.1 Molecular Beams.- 2.1.1 Continuous Effusive Beams.- 2.1.2 Continuous Supersonic Beams.- 2.1.3 Pulsed Beams.- 2.2 Nucleation and Aggregation Processes.- 2.2.1 Classical Theory.- 2.2.2 Homogeneous Nucleation by Monomer Addition.- 2.2.3 Homogeneous Nucleation by Aggregation.- 2.2.4 Nucleation of Clusters in Beams.- 2.2.5 Semi-empirical Approach to Clustering in Free Jets.- 3. Cluster Sources.- 3.1 Vaporization Methods.- 3.1.1 Joule Heating.- 3.1.2 Plasma Generation for Cluster Production.- 3.1.3 Laser Vaporization.- 3.1.4 Glow and Arc Discharges.- 3.2 Continuous Sources.- 3.2.1 Effusive Joule-Heated Gas Aggregation Sources.- 3.2.2 Magnetron Plasma Sources.- 3.2.3 Supersonic Sources.- 3.3 Pulsed Sources.- 3.3.1 Pulsed Valves.- 3.3.2 Laser Vaporization Sources.- 3.3.3 Arc Pulsed Sources.- 4. Characterization and Manipulation of Cluster Beams.- 4.1 Mass Spectrometry.- 4.1.1 Quadrupole Mass Spectrometry.- 4.1.2 Time-of-Flight Mass Spectrometry.- 4.1.3 Retarding Potential Mass Spectrometry.- 4.2 Detection Methods.- 4.2.1 Ionization of Clusters.- 4.2.2 Charged Cluster Detection.- 4.2.3 Cluster Beam Characterization.- 4.3 Cluster Selection and Manipulation.- 4.3.1 Size and Energy Selection.- 4.3.2 Quadrupole Filter.- 4.3.3 Separation of Gas Mixtures in Supersonic Beams.- 5. Thin Film Deposition and Surface Modification by Cluster Beams.- 5.1 Kinetic Energy Regimes.- 5.2 Diffusion and Coalescence of Clusters on Surfaces.- 5.3 Low-Energy Deposition.- 5.3.1 Cluster Networks and Porous Films.- 5.3.2 Composite Nanocrystalline Materials.- 5.4 High-Energy Deposition.- 5.4.1 Implantation, Sputtering, Etching.- 5.4.2 Thin Film Formation.- 6. Outlook and Perspectives.- 6.1 Cluster Beam Processing of Surfaces.- 6.2 Nanostructured Materials Synthesis.- 6.3 Perspectives.- References.

Cluster Beam Synthesis of Nanostructured Materials

This perspective deals with the coupling of ionic and electronic transport in organic electronic devices, focusing on electrolyte-gated transistors. These include electrolyte-gated organic field-effect transistors (EG-OFETs) and organic electrochemical transistors (OECTs). EG-OFETs, based on molecules and polymers, can be operated at low electrical bias (about 1 V or below) and permit unprecedented charge carrier densities within the transistor channel. OECTs can be operated in aqueous environment as efficient ion-to-electron converters, thus providing an interface between the worlds of biology and electronics. The exploration and the exploitation of coupled ionic and electronic transport in organic materials brings together different disciplines such as materials science, physics, chemistry, electrochemistry, organic electronics and biology.

New opportunities for organic electronics and bioelectronics: ions in action

We use a seeded supersonic molecular beam to control the kinetic energy of pentacene (${\mathrm{C}}_{22}{\mathrm{H}}_{14}$) during deposition and growth on Ag(111). Highly ordered thin films are grown at low substrate temperatures ($\ensuremath{\sim}200\text{ }\mathrm{K}$) at kinetic energies of a few electron volts, as shown by low energy He diffraction and x-ray reflectivity spectra. In contrast, deposition of thermal molecules yields only amorphous films. Growth at room or higher temperature substrates yields films of poorer quality irrespective of the depositing beam energy. We find that after the first wetting layer is completed, a new ordered phase is formed, whose in-plane lattice spacings match one of the bulk crystal planes. The high quality of the films can be interpreted as the result of local annealing induced by the impact of the impinging high-energy molecules.

Hyperthermal molecular beam deposition of highly ordered organic thin films.

Organic electrochemical transistors (OECTs) are attracting a great deal of interest for biosensing and bioelectronics applications. However, their device physics is not yet well-understood. In this paper, we focus on the effect of the gate electrode material on the response of OECTs. We studied OECTs made from the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate), and which utilized halide electrolytes. We demonstrate that OECTs with Ag gate electrodes show larger current modulation compared to OECTs with Pt gate electrodes. This effect is due to a change in the OECT regime of operation from capacitive, in case of a Pt gate electrode, to Faradaic, in the case of an Ag electrode.

Salvatore Iannotta

Papers

Pentacene Thin Film Growth

Cluster Beam Synthesis of Nanostructured Materials

New opportunities for organic electronics and bioelectronics: ions in action

Hyperthermal molecular beam deposition of highly ordered organic thin films.

Effect of the gate electrode on the response of organic electrochemical transistors