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The synthesis of cupric oxide (CuO) films on cost-efficient, optical grade borosilicate-crown glass substrates (BK7) via chemical spray pyrolysis (CSP), either in pure form or with a low concentration of Al doping (below 1%), is presented and discussed. As a non-toxic p-type semiconductor, exhibiting monoclinic crystal structure and widely tuneable band gap (Eg), it is used in various applications. The optical properties, morphology and crystalline phases of CuO films are influenced by substrate temperature during thin film growth (annealing) and also by chemical doping very often introduced to modify grain boundary energy. The importance of our research subject is therefore perfectly justified and is essentially based on the fact that the potential fields of application are wide. Thus, herein we emphasize impact of the annealing stage and Al doping upon the structural, optical and electrical properties of the resulting product. Raman spectroscopy analysis confirms the presence of vibrational bands characteristic of a CuO phase, while X-ray diffraction (XRD) confirms the polycrystalline nature of the pure films. The thickness of the CuO films grown at 350 °C over three annealing intervals is proportional to the annealing time, while the crystallite phase in the films is proportional with the annealing temperature. Furthermore, XRD analysis of the Al:CuO films indicates the formation of a monoclinic-type structure (CuO phase) exhibiting a preferred orientation along the (002) plane, together with a significant grain size reduction from ~88 to ~45 nm as Al content increases. The transmittance spectra (between 400 and 800 nm) reveal a decrease in the transmittance from 48% to 15% with as the Al doping ratio increases. Additionally, the bandgap energy of the films is measured, modelled and discussed, using data from an ultraviolet–visible (UV-Vis) spectrophotometer. The calculated Eg is approximately 3.5 eV, which decreases with respect to the increasing annealing temperature, while the electrical resistivity varies from ~19 to ~4.6 kOhm.cm. Finally, perspectives and applications of CuO films are suggested, since the films are found to have a remarkable improvement in their structure and optical properties when doped with Al. [ABSTRACT FROM AUTHOR]

Thin solid pixels made of Ag/PMMA stacks have been fabricated by laser-induced forward transfer (LIFT), to be tested as thin film microcapacitors in organic electronics applications. The square-shaped laser-printed pixels have a lateral size of ∼350 μm, and the thickness of the dielectric film was varied between 100 and 1500 nm. The pixels were deposited on electrode structures made by LIFT printing of silver nanoparticles ink and paste. Optimal printing conditions led to the fabrication of microcapacitors with typical capacitance in the pF range, tuned by changing the properties of the multilayered structure (e.g. pixel size and/or thickness of the dielectric). Their stability was also investigated over time. We discuss on the morphological and electrical properties of such laser-printed structures, with respect to the impact resistance of the polymer and its suitability for the LIFT process. [ABSTRACT FROM AUTHOR]

Following the standard Sonogashira cross-coupling conditions, the reaction between 1,4-diiodo-2,5-bis(octyloxy)benzene with 2.2 equiv. of 1-ethynylpyrene afforded a yellowish bis -pyrene derivative, namely 1,4-bis(octyloxy)-2,5-bis(ethynylpyrene)benzene , that exhibits typical fluorescence and semiconducting properties. Thermal analysis studies are discussed, with emphasis made on the oxidative decomposition and thermal effects. Further on, thin films have been grown by vacuum thermal evaporation, on silicon and quartz substrates. The temperature's influence on the thin film's morphology and electrical properties is investigated. Finally, top-contact thin film transistor configurations are presented and the influence of substrate temperature is discussed with respect to the semiconducting properties. [ABSTRACT FROM AUTHOR]

We present results on a newly synthesized bis -pyrene compound that, besides the typical fluorescence, also exhibits semiconducting properties. Thin films have been grown by vacuum thermal evaporation on oxidized silicon and on transparent quartz substrates. Micrometric-sized pixels have subsequently been printed by laser-induced forward transfer (LIFT), in air and at low pressure (90 mbar), by using a Nd:YAG laser source (355 nm, 50 ps pulse duration) to produce functional organic thin film transistors (o-TFTs). Top-contact (TC) configurations are emphasized, and the influence of the pressure and laser fluence during the LIFT procedure is discussed. [ABSTRACT FROM AUTHOR]

Thermal behavior studies of several polymers, i.e. polyvinyl chloride (PVC), polyacrylic acid (PAA), and polyaniline (PAni), together with thin film deposition by a MAPLE technique, are presented. Thermal stability studies are important before attempting any laser-assisted processing of such materials, as this provides a better understanding of their molecular behavior, to assess the evolution and dynamics of the deposition. Thin films were grown on silicon substrates by means of matrix-assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser (266 and 355 nm, 7 ns pulse duration). Above the fluence of ~0.7 J/cm 2 the polymeric films are highly non-uniform due to the transferring of matrix-droplets and/or clusters from the target. At low fluence, typically between 0.1 and 0.5 J/cm 2 , the polymeric films are intact; the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the films. The important question of polymeric molecules integrity in the films with respect to that of the targets is discussed, in relation to their properties, and compared to data available in the literature. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ferrocenecarboxaldehyde thin films are grown on silicon substrates, by MAPLE. [•] Thin films with low roughness and preserved chemical structure are obtained. [•] Second harmonic generation capabilities of films are evidenced. [Copyright &y& Elsevier]

Abstract: Ferrocene – Fe(C5H5)2, the prototypical metallocene, is a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom. We discuss here on the growth of high quality, nanometric-sized ferrocene thin films by a non-conventional technique, i.e. matrix-assisted pulsed laser evaporation (MAPLE), on silicon and ITO coated glass substrates, by using a Nd:YAG pulsed laser device emitting at 266 nm (4ω). Spectroscopic-ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy techniques were used to investigate the structure, morphology and optical properties of the films. Low-to-medium second harmonic generation capabilities of the films were evidenced, when irradiated by a femtosecond Ti:sapphire pulsed laser. [Copyright &y& Elsevier]

Abstract: Thin films based on two different metal–organic systems are developed by MAPLE and their nonlinear optical applications are explored. A complex of o,o′-dihydroxy azobenzene with Cu2+ cation is found to organize as a non-central symmetric crystallite. A simple protocol is developed for the in situ fabrication of highly monodisperse copper-complex nanoparticles in a polymer film matrix of polyacrylic acid. The thin films were deposited on quartz substrates by MAPLE (matrix assisted pulsed laser evaporation) using a Nd:YAG laser working at 355nm. Atomic force microscopy (AFM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and optical second harmonic generation (SHG) were performed on the samples. The optical limiting capability of the nanoparticle-embedded polymer film is investigated. [Copyright &y& Elsevier]

We report on the thin film growth of 1,2,3,4,5,6,7,8-octahydroacridine (OHA) by matrix-assisted pulsed laser evaporation (MAPLE), starting from a frozen solution of 1% OHA dissolved in methanol and using a Nd:YAG laser emitting at 266 nm wavelength with fluences in the range 0.1–1 J/cm 2 . The optical properties were studied by spectroscopic-ellipsometry (SE), while Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were performed for structure and surface morphology investigation. Second harmonic generation (SHG) capabilities of the thin films were investigated by using a tunable Ti:sapphire laser with maximum emission centred in near infra-red. The peak of emitted photons is located at 388 nm, therefore half the wavelength of the initial photons (776 nm). The semi logarithmic dependence of SHG intensity on incident power is almost linear, except the value obtained at highest power of incident photons. This value indicates a local changing of sample due to the heating produced by the high-power incident beam. [ABSTRACT FROM AUTHOR]

Abstract Thin films of pentacene, i.e. a polycyclic hydrocarbon consisting of five linearly-fused benzene rings, are grown on silicon and quartz (SiO 2) substrates by matrix assisted pulsed laser evaporation (MAPLE) and by using toluene as a frozen matrix (melting point: −95 °C). The thin film samples are subsequently investigated for their optical, morphological and chemical structure, i.e. by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and spectroscopic-ellipsometry (SE). Due to its highly conjugated aromatic behaviour, pentacene exhibits semiconductor properties and has been shown to generate excitons upon absorption of ultra-violet (UV) or visible light. Here, we study the excited state dynamics of pentacene, in bulk and as thin films, after optical excitation, by using femtosecond (fs) time-resolved second harmonic generation (SHG). A pulsed femtosecond Ti:sapphire laser (80 MHz repetition rate, 800 nm, 100 fs) is employed to demonstrate the SHG potential of such polycyclic aromatic hydrocarbon simple molecule. The substrates used in studying the films are inert and non-interacting, known to deliver no noteworthy contribution to the SHG signal. Therefore, the pure response of pentacene to the electronic excitation can be resolved in contrast to the measurements on SiO 2. Finally, a comparative discussion of our results is made with respect to literature. This study provides important insights on the excited states dynamics of pentacene, an essential step for understanding the photophysics of simple, linearly-fused arenes. Graphical abstract Unlabelled Image Highlights • The growth, morphological, chemical, and optical properties of pentacene films are discussed. • The compound has been shown to generate excitons upon absorption of UV or visible light. • The nonlinear behaviour is highlighted by the regular shape of the emission band. • Strong SHG signal and high resistance to incident laser beam is shown. [ABSTRACT FROM AUTHOR]