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Solution‐processed organic and hybrid semiconductor materials have great potential for ionizing radiation direct detection, as they combine high sensitivity, low‐power consumption, and flexibility. There is, however, an open challenge related to the stability in ambient/operational conditions of this class of devices. In this work, an air‐stable, solution‐processed and flexible X‐ray detector is reported, based on the integration of hybrid perovskite and organic thin films used as active layer and functional interlayers, respectively. The diode architecture and the engineering of the interface between the hybrid perovskite and the organic hole transporting material (solvent‐modified poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate) is the key to achieve enhanced detector's air stability and performance. The unencapsulated flexible device, measured in air and in passive operation (0 V), shows a limit‐of‐detection of 0.37 ± 0.04 µGy s−1 and a sensitivity as high as 5.2 µC Gy−1 cm−2, which is retained within 25% after 42 days exposure to ambient conditions. [ABSTRACT FROM AUTHOR]

The patterning of composites with carbon-based additives of nanometer or micrometer size was studied by the precise modification of material surfaces using laser technology. Initially, the composites are electrical insulators, but we can make them conductive by selective patterning; this process allows us to create conductive tracks within seconds, with a sheet resistance that can be adjusted over a wide range, from 108 Ω/sq down to 2.5 Ω/sq. The additives used include graphene nanoplatelets, graphene oxide nanosheets, and aramid fibers. By conducting microscopic and spectroscopic characterizations before and after laser treatment, we can distinguish between two different processes that lead to electrical conduction: (a) localized increase in the concentration of conductive additives or (b) localized reduction and pyrolysis of insulating additives. To demonstrate the versatility and usefulness of this technique in different fields of application, such as automotive, we fabricate three different devices on polyurethane: a heater, a proximity sensor, and an amperometric sensor for detecting biological analytes. [ABSTRACT FROM AUTHOR]

Among solution-processable metal oxides, zinc oxide (ZnO) nanoparticle inks are widely used in inverted organic solar cells for the preparation, at relatively low temperatures (<120 °C), of highly efficient electron-transporting layers. There is, however, a recent interest to develop more sustainable and less impacting methods/strategies for the preparation of ZnO NPs with controlled properties and improved performance. To this end, we report here the synthesis and characterization of ZnO NPs obtained using alternative reaction solvents derived from renewable or recycled sources. In detail, we use (i) recycled methanol (r-MeOH) to close the loop and minimize wastes or (ii) bioethanol (b-EtOH) to prove the effectiveness of a bio-based solvent. The effect of r-MeOH and b-EtOH on the optical, morphological, and electronic properties of the resulting ZnO NPs, both in solution and thin-films, is investigated, discussed, and compared to an analogous reference material. Moreover, to validate the properties of the resulting materials, we have prepared PTB7:PC71BM-based solar cells containing the different ZnO NPs as a cathode interlayer. Power conversion efficiencies comparable to the reference system (≈7%) were obtained, validating the proposed alternative and more sustainable approach. [ABSTRACT FROM AUTHOR]

A four-step methodology for the valorization of polysaccharide-based materials into bifunctional heterogeneous catalysts, active in the conversion of CO2 and epoxides into cyclic carbonates, is presented. The synthesis protocol consists of (i) pyrolysis of the starting material to produce biochar; (ii) oxidation to increase the number of –OH and –COOH functionalities; (iii) anchoring of (3-aminopropyl)triethoxysilane (APTES) on the surface of the oxidized biochar; (iv) quaternarization of the amine groups into alkylammonium iodide salts. The versatility of the method was demonstrated by applying the same protocol to six different polysaccharidic materials and wastes: six catalysts with no appreciable differences in terms of chemical composition and catalytic activity were obtained. The bifunctionality given by –OH and ammonium iodide groups was confirmed by several analyses performed on the catalysts. An extensive characterization (elemental analysis composition, FTIR, Raman, SEM, XPS and porosimetry) was done on all the functionalized biochars for every synthetic step. The catalysts were widely investigated in their activity for the conversion of CO2 and epoxides into cyclic carbonates, demonstrating to be effective under mild conditions (3 bar of CO2; 70 °C; 7 h). TONs and TOFs were calculated for each catalyst and condition. Yields up to 96%, with >99% selectivity, were obtained for terminal epoxides. The recyclability of the bifunctional heterogeneous catalysts was also confirmed over five cycles. [ABSTRACT FROM AUTHOR]

Due to their exceptional properties, the study of hybrid perovskite (HyP) structures and applications dominate current photovoltaic prospects. Methylammonium lead tri-iodide perovskite (MAPI) is the model compound of the HyP class of materials that, in a few years, achieved, in photovoltaics, a power conversion efficiency of 25%. The attention on HyP has recently moved to large single crystals as emerging candidates for photovoltaic application because of their improved stability and optoelectronic properties compared to polycrystalline films. To control the quality and symmetry of the large MAPI single crystals, we proposed an original method that consisted of adding short-chain carboxylic acids to the inverse temperature crystallization (ICT) of MAPI in γ-butyrolactone (GBL). The crystals were characterized by single-crystal X-ray diffraction (SC-XRD), X-ray powder diffraction (XRPD) and Raman spectroscopy. Based on SC-XRD analysis, MAPI crystals grown using acetic and trifluoroacetic acids adopt a tetragonal symmetry "I4cm". MAPI grown in the presence of formic acid turned out to crystallize in the orthorhombic "Fmmm" space group demonstrating the acid's effect on the crystallization of MAPI. [ABSTRACT FROM AUTHOR]

The quality and the performance of hybrid perovskite (HP)'s films strongly depend on the complete conversion into MAPbI3 of a spin-coated solution of methylammonium iodide (MAI) and PbI2. Highly crystalline PbI2 on a substrate limits such a conversion and, consequently, the HP's solar cell performances. We investigate for the first time the use of short-chain organic acids as additives in a non-complexing solvent like γ-butyrolactone (GBL), that can retard retard the crystallization of PbI2. Based on XRD analyses of the spin coated films, the acetic acid is the most effective additive in retarding the PbI2 crystallization, making Pb2+ available for a subsequent reaction with MAI. These results open a new experimental path for fabricating perovskite films by single or sequential step methods involving acid additives. [ABSTRACT FROM AUTHOR]

Here, we exploited the UV light and thermal triggered E ↔ Z photoisomerization of an azobenzene compound to fabricate multimodal readable and rewritable data matrix based devices. We first demonstrated that the UV light sensing capabilities can be simultaneously monitored by the change in optical, spectroscopic, and electrical properties. Then we exploited this capability by integrating tetra(azobenzene)methane crystals in a micrometric TAG whose information can be modified and repristinated by local UV treatment and thermal annealing. The system was characterized by polarized optical microscopy, Raman spectroscopy, conductive atomic force microscopy and Kelvin Probe Force Microscopy. [ABSTRACT FROM AUTHOR]

Skin disorders are widespread around the world, affecting people of all ages, and oxidative stress represents one of the main causes of alteration in the normal physiological parameters of skin cells. In this work, we combined a natural protein, fibroin, with antioxidant compounds extracted in water from pomegranate waste. We demonstrate the effective and facile fabrication of bioactive and eco-sustainable films of potential interest for skin repair. The blended films are visually transparent (around 90%); flexible; stable in physiological conditions and in the presence of trypsin for 12 days; able to release the bioactive compounds in a controlled manner; based on Fickian diffusion; and biocompatible towards the main skin cells, keratinocytes and fibroblasts. Furthermore, reactive oxygen species (ROS) production tests demonstrated the high capacity of our films to reduce the oxidative stress induced in cells, which is responsible for various skin diseases. [ABSTRACT FROM AUTHOR]

The development of efficient, reliable, and clean energy sources is one of the global priorities for enabling a sustainable transition toward a green society and economy. The third‐generation solar cells, such as organic solar cells (OSCs) and perovskite solar cells (PSCs), are among the most promising platforms for the generation of electrical power from sunlight for a wide range of applications. However, the widespread diffusion of emerging photovoltaics technologies is hampered by issues occurring in the translation of laboratory‐scale R&D efforts to real settings. Herein, starting from a thorough survey of latest research on OSC and PSC technologies, critical factors related to fabrication and operation of solar cells, especially in terms of materials properties/requirements and beyond metrics built on efficiency only, are analyzed. On this basis, OSCs and PSCs are compared in terms of their potential in real application scenarios, also highlighting their peculiarities in view of their future large‐scale utilization. [ABSTRACT FROM AUTHOR]

Commercial hollow fiber filters for micro- and ultrafiltration are based on size exclusion and do not allow the removal of small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone–polyvinylpyrrolidone hollow fiber (Versatile PES®, hereafter PES) modules and that the resulting core–shell fibers inherits the microfiltration ability of the pristine PES fibers and the adsorption selectivity of GO. GO nanosheets were deposited on the fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1–0.2 μm), then fixed by thermal annealing at 80 °C, rendering the GO coating stably fixed and unsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water and bovine plasma spiked with bovine serum albumin (BSA, 66 kDa, ≈15 nm size), monodisperse polystyrene nanoparticles (52 nm and 303 nm sizes), with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that the microfiltration capability of PES was retained by HF-GO, and in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show that the separation mechanism does not rely only on physical size exclusion, but involves intercalation of solute molecules between the GO layers. [ABSTRACT FROM AUTHOR]

Aqueous suspensions of composite nanoparticles of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) are fabricated by miniemulsion method using three different ionic surfactants. The aim is to study how the length and conformation of the surfactants alkyl chains affect the properties of the nanoparticles. While the morphology and dimensions of the nanoparticles are similar, UV–vis spectroscopy evidences that the internal aggregation and ordering of the P3HT chains varies within the three nanoparticle formulations. The surfactant with branched alkyl chains promote the highest degree of ordering of P3HT chains in the nanoparticles (leading to increased conjugation length). In contrast, the lowest ordering is found for the nanoparticles with the surfactant having the shortest linear alkyl chain. The optical/structural properties of nanoparticles are partially retained in the films. Besides, the surfactant with branched alkyl chains favors the strongest coalescence of nanoparticles in the thin film, promoting a further ordering of the polymeric chains in the most external shell of the nanoparticles as evidenced by steady‐state and time‐resolved UV–vis spectroscopy and confocal fluorescence microscopy. These findings might guide the engineering of new surfactants for composite nanoparticles for optoelectronic applications. [ABSTRACT FROM AUTHOR]

A new approach to the analysis of the internal phonons of tris(quinolin-8-olato) aluminum(III) is presented, which enlightens the role played by the ligands in determining the vibrational properties of the organometallic compound and evidences the importance of the contributions arising from the coupling terms among the three quinolinato fragments. An accurate exam of the normal modes of the meridianal isomer evidences the role of the interactions among the fragments in the vibrational dynamics of the ground state. Due to the special attention paid to the quinolinato fragments, a preliminary investigation on the vibrational properties of 8-hydroxyquinoline, taken as a model fragment, was also performed. The vibrational properties of the polymorph species β of the organometallic molecule were obtained refining the calculated frequencies, the dipole moment derivative matrix, and the polarizability derivative tensor derived by the hybrid density functional B3LYP/6-31G* comparing with the frequencies and intensities recorded by the infrared and the Raman spectroscopies performed on a polycrystalline sample. One thus obtains the most accurate intramolecular force constants up to date for the meridianal isomer in a crystalline phase. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The parent compound of high-Tc superconducting cuprates is a unique Mott insulator consisting of layers of spin-1/2 ions forming a square lattice and with a record high in-plane antiferromagnetic coupling. Compounds with similar characteristics have long been searched for without success. Here, we use a combination of experimental and theoretical tools to show that commercial AgF2 is an excellent cuprate analog with remarkably similar electronic parameters to La2CuO4 but larger buckling of planes. Two-magnon Raman scattering and inelastic neutron scattering reveal a superexchange constant reaching 70% of that of a typical cuprate. We argue that structures that reduce or eliminate the buckling of the AgF2 planes could have an antiferromagnetic coupling that matches or surpasses the cuprates. [ABSTRACT FROM AUTHOR]

Abstract: Mussel‐inspired polydopamine (PD) coating represents a promising route for constructing functional materials and finely tuning or completely changing their surface properties. In this work, a mild and effective method to realize the deposition of PD on keratin‐based films is reported. Reactive oxygen species (ROS), generated by keratin films doped with a photosensitizer, e.g., Azure A (AzA), upon UV–vis and vis‐near IR irradiation, are exploited to obtain the PD coating. Interestingly, the use of vis‐near IR irradiation leads to an increased production of ROS by AzA resulting in a greater PD deposition. Compared to uncoated keratin films, the PD‐keratin coated materials show a granular but homogeneous surface and an increased hydrophilicity, maintaining the ROS generation ability of AzA. This work demonstrates a useful method to effectively and rapidly functionalize with PD materials that are sensitive to temperature, pH and UV light, such as keratin. The proposed strategy allows obtaining new multifunctional biomaterials of potential interest in tissue engineering and drug delivery; in particular, the use of PD‐keratin films for near IR laser bonding of ophthalmic tissue, which is a representative case in wound healing purpose, is shown. [ABSTRACT FROM AUTHOR]

A robust and efficient interconnection layer (ICL) based on low conductive poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and ZnO nanoparticles is implemented in a solution-air-processed, blade coated inverted polymer tandem solar cell. The commercial PEDOT:PSS (Heraeus Clevios P VP Al 4083) is modified with a fluorosurfactant to allow its deposition onto any hydrophobic active layer surface. However, this method alters the electrical and energetic properties of the PEDOT:PSS thus affecting the interface with the ZnO layer, responsible for an inefficient ICL and poorly performing tandem devices. The ohmic contact at the PEDOT:PSS/ZnO interface is successfully optimized through a simple solvent treatment of the PEDOT:PSS film surface, leading to tandem devices with power conversion efficiencies (PCEs) improved by more than 50% compared to the untreated reference system. The reported method is an easy and versatile approach to optimize the functionality of the PEDOT:PSS/ZnO ICL of inverted multijunction devices, applicable onto any organic active layer and compatible with a roll-to-roll production line. [ABSTRACT FROM AUTHOR]

The dynamic evolution of the vibrational interactions in the prototypical CH3NH3PbI3 was studied through a comprehensive experimental and theoretical investigation with a focus on the interactions between the organic cations and the inorganic cage. To date, no clear picture has emerged on the critical and fundamental interactions between the two perovskite components, despite the relevance of phonons to the electronic properties of several classes of perovskites. For the first time, we have monitored the IR and nonresonant Raman response in the broad frequency range 30-3400 cm-1 and in the temperature interval 80-360 K. Strong changes in the energies of different vibrational modes with temperature are observed and examined in the framework of phonon-phonon interactions considering a significant anharmonic contribution to the phonon relaxation process. The vibrational relaxation of the bending modes and their reorientation activation energies identify that such mechanisms are governed by medium-tostrong hydrogen bonds in the orthorhombic phase; however, any ferroelectric ordering in the orthorhombic phase is governed mostly by dipole interactions. These changes imply that charge localization mechanisms play a primary role, and our study enriches the fundamental knowledge of phonon interactions and charge transport in CH3NH3PbI3 for the further development of optoelectronic applications. [ABSTRACT FROM AUTHOR]

ABSTRACT The use of doped silk fibroin (SF) films and substrates from Bombyx mori cocoons for green nanotechnology and biomedical applications has been recently highlighted. Cocoons from coloured strains of B. mori, such as Golden-Yellow, contain high levels of pigments that could have a huge potential for the fabrication of SF based biomaterials targeted to photonics, optoelectronics and neuroregenerative medicine. However, the features of extracted and regenerated SF from cocoons of B. mori Golden-Yellow strain have never been reported. Here we provide a chemophysical characterization of regenerated silk fibroin (RSF) fibers, solution, and films obtained from cocoons of a Golden-Yellow strain of B. mori, by SEM, 1H-NMR, HPLC, FT-IR, Raman and UV-Vis spectroscopy. We found that the extracted solution and films from B. mori Golden-Yellow fibroin displayed typical Raman spectroscopic and optical features of carotenoids. HPLC-analyses revealed that lutein was the carotenoid contained in the fiber and RSF biopolymer from yellow cocoons. Notably, primary neurons cultured on yellow SF displayed a threefold higher neurite length than those grown of white SF films. The results we report pave the way to expand the potential use of yellow SF in the field of neuroregenerative medicine and provide green chemistry approaches in biomedicine. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 287-299, 2016. [ABSTRACT FROM AUTHOR]

We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations. [ABSTRACT FROM AUTHOR]

Organo-halide lead perovskites are revolutionizing the photovoltaic scenario, with efficiencies exceeding 15%. The orientational dynamics disorder of the methylammonium cations (MA) is one of the most peculiar features of these materials. Here, we perform ab initio molecular dynamics simulations and IR spectroscopic measurements on lead halide hybrid perovskites to elucidate the rotational motion of the MA cations in these systems and its effects on the structural and electronic properties of hybrid perovskites. In the investigated time frame, the MA cations are found to rotate within the inorganic framework on a timescale of a few ps. A variation of ±0.1 to 0.2 eV of the electronic properties with the ion dynamics is found, which increases upon increasing the temperature. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF), a protein core fibre from the silkworm Bombyx mori, has huge potential to become a sustainable, biocompatible, and biodegradable material platform that can pave the way towards the replacement of plastic in the fabrication of bio-derived materials for a variety of technological and biomedical applications. SF has remarkable mechanical flexibility, controllable biodegradability, biocompatibility and is capable of drug/doping inclusion, stabilization and release. However, the dielectric properties of SF limit its potential as a direct bioelectronic interface in biomedical devices intended to control the bioelectrical activity of the cell for regenerative purposes. In this work, a novel wet templating method is proposed to generate nanostructured, conductive Silk Fibroin (SF) composite films. We combine the unusual properties of SF, such as its mechanical properties, its convenience and biocompatibility with the electrical conductivity and stiffness of Single Walled Carbon Nanotubes (SWCNTs). The presented SF–SWCNT composite displays a periodic architecture where SWCNTs are regularly and homogeneously distributed in the SF protein matrix. The morphological and chemo-physical properties of the nanocomposite are analysed and defined by SEM, Raman Spectroscopy, ATR-IR, UFM and contact angle analyses. Notably, the SF–SWCNT composite film is conductive, showing additional functionality compared to the dielectric properties of the bare SF film. Finally, SF–SWCNT is biocompatible and enables the growth of primary rat Dorsal Root Ganglion (DRG) neurons. Collectively our results demonstrate that the nanostructured, conductive, robust and biocompatible SF–SWCNT composite can be fabricated using a wet templating method, paving the way towards the fabrication and development of silk-based electronic devices for use in bioelectronic and biomedical applications. [ABSTRACT FROM AUTHOR]

The basic concept for efficiency improvement in dye-sensitized solar cells (DSSC) is limiting the electron-hole recombination. One way to approach the problem is to improve the photogenerated charge carriers lifetime and consequently reduce their recombination probability. We are reporting on a facile posttreatment of the mesoporous photoanode by using a colloidal solution of TiO2 nanoparticles. We have investigated the outcome of the different sintering temperature of the posttreated photoanodes on their morphology as well as on the conversion efficiency of the DSSC. The DSSCs composed of posttreated photoanodes at 450°C showed an increase in JSC and consequently an increase in efficiency of 10%. Investigations were made to determine the electron recombination via the electrolyte by the OCVD technique. We found that the posttreatment has the effect of reducing the surface trap states and thus increases the electron lifetime, which is responsible for the increase of the overall cell efficiency. [ABSTRACT FROM AUTHOR]

Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that hold great promise for a variety of applications, including flat panel displays, integrated light sources for sensing and optical communication systems. The narrow illumination area within the device channel is considered intrinsic to the device architecture and is a severe technological drawback for all those applications where a controlled, wide and homogeneous emission area is required. Here it is shown that not only the position but also the extension of the emission area is voltage-tunable, and the entire channel of the transistor can be homogeneously illuminated. The modeling of the exciton distribution within the channel at the different bias conditions coupled to the modeling of the device emission profile highlights that excitons are spread through the entire channel width and across the bulk of the central emission layer of the p-channel/emitter/n-channel trilayer active heterostructure. [ABSTRACT FROM AUTHOR]

The bioelectrical signalling within neural networks has to be monitored in real-time and localized in space in order to unravel the mechanisms behind pathologies and diseases of the nervous systems. Organic materials have significant potential for bio-functional neural interfacing given that their “soft” nature offers better mechanical compatibility with the nerve tissues than conventional semiconductors, and their flexibility allows realization of the non-planar forms typically required for biomedical implants. The integration of living cells into organic semiconductors is an important step towards the development of bio-organic electronic transducers of cellular activity from neurons. Here, we report on the use and characterization of n-type perylene derivatives as a suitable interface platform for organic neuro-electronic devices. We demonstrate that primary neurons can adhere, grow and differentiate on a suitably engineered perylene-based field-effect transistor platform, while maintaining their firing properties even after a prolonged time of cell-culturing. It is noteworthy that the field-effect transistors preserve their electrical characteristics even after 10 days of incubation in cell culture media. These results validate n-type perylene derivatives as a suitable long-term interface platform for organic neuro-electronic devices, which is particularly relevant in view of the recently reported perylene-based field-effect transistor structure capable of providing bidirectional stimulation and recording of primary neurons. [ABSTRACT FROM AUTHOR]

Real-time stimulation and recording of neural cell bioelectrical activity could provide an unprecedented insight in understanding the functions of the nervous system, and it is crucial for developing advanced in vitro drug screening approaches. Among organic materials, suitable candidates for cell interfacing can be found that combine long-term biocompatibility and mechanical flexibility. Here, we report on transparent organic cell stimulating and sensing transistors (O-CSTs), which provide bidirectional stimulation and recording of primary neurons. We demonstrate that the device enables depolarization and hyperpolarization of the primary neuron membrane potential. The transparency of the device also allows the optical imaging of the modulation of the neuron bioelectrical activity. The maximal amplitude-to-noise ratio of the extracellular recording achieved by the O-CST device exceeds that of a microelectrode array system on the same neuronal preparation by a factor of 16. Our organic cell stimulating and sensing device paves the way to a new generation of devices for stimulation, manipulation and recording of cell bioelectrical activity in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Indium sulphide has been extensively investigated as a component for different kind of photovoltaic devices (organic-inorganic hybrid devices, all inorganic, dye sensitized cells). In this paper, we have optimised the growth conditions of indium sulphide thin films by means of a low cost, versatile deposition technique, like spray pyrolysis. The quality of the deposited films has been characterised bymicro-Raman, vis-UV spectroscopy, and atomic force microscopy. Substrate deposition temperature and different postdeposition annealing conditions have been investigated in order to obtain information about the quality of the obtained compound (which crystalline or amorphous phases are present) and the morphology of the deposited films. We have shown that the deposition temperature influences strongly the amount of amorphous phase and the roughness of the indium sulphide films. Optimised postdeposition annealing treatments can strongly improve the final amount of the beta phase almost independently from the percentage of the amorphous phase present in the as deposited films. [ABSTRACT FROM AUTHOR]

Technological procedures able to produce high quality electrodes from magnetic oxides in vertical organic-inorganic hybrid devices is a challenging task in the field of organic spintronics. Thin films of magnetite (Fe3O4) have been successfully grown directly on top of organic semiconductor layers, tris(8-hydroxyquinoline)aluminium(III) (Alq3), by pulsed-electron ablation technique. The films show ferromagnetic behavior and good structural quality, properties detected by magneto-optical Kerr effect, superconductor quantum interference device, micro-Raman spectroscopy, and Atomic Force Microscopy. The ferromagnetic behavior persists even for 10 nm thick films. Charge injection at magnetite-organic interface has been finally demonstrated by detecting electroluminescence from Alq3. [ABSTRACT FROM AUTHOR]

The polarized infrared absorption and Raman spectra on the bc plane of a single crystal of α-sexithienyl (α-T6) have been recorded in the range from 50 up to 3500 cm-1. The intermolecular interactions give rise to the Davydov splitting of the ungerade phonon energy levels originated by the molecular pyramidalization along with the CCH bending modes. A μ-Raman investigation on the crystal surface allows identification of the perturbed local packing of the molecules, which are spectroscopically crystal defects. The selective resonant enhancement of the scattering intensity of some Raman modes, obtained by exciting at λ[sub ex]=632.8 nm, indicates that these defects are associated with the lowering of the electronic excited states due to the increased π-orbital overlapping. Moreover, the resonant enhancement allows detection of some of the gerade intramolecular phonons not observed in the bulk. The comparison between the far-infrared absorption spectra recorded at room temperature and at 80 K evidences three lattice phonons. The spectral analysis, based on a simulation, which uses a scaled ab initio molecular force field, well interprets the experimental data assigning all the internal phonons and elucidates some of the effects of the intermolecular interactions. The calculations are performed at the HF/6-31 G* level of the theory to obtain the harmonic frequencies and the dipole moment and polarizability tensor derivatives of the α-T6 molecule. Both polarized infrared and Raman spectra simulations are carried out calculating the optical response of a unit cell of the α-T6 single crystal belonging to the C[sub 2h] factor group in the monoclinic P2[sub 1]/n space group. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This work describes the preparation of a novel substrate based on keratin extracted from wool and its application as potential support for solution‐processed organic solar cells. Optically transparent, free‐standing, and resistant keratin films are successfully prepared, starting from water solution, and characterized in terms of morphology, structure, thermal and mechanical properties. The effect of solvents and thermal annealing is also investigated in order to mimic and evaluate the impact of the processing conditions used for devices fabrication. Thermally annealed keratin films exhibit enhanced optical transparency (>87%) in the visible region of the spectrum, a transition from α‐helix to β‐sheet and turn structures, improved thermal stability and Young's modulus. The good transparency, flatness, and resistance of as‐cast substrates allow the successful preparation of organic solar cells. Photovoltaic performances similar to those reported for other natural/biobased supports are achieved, confirming the potential of keratin film as an alternative and promising support material for eco‐friendly, fully printable, sustainable, and inexpensive optoelectronic devices. [ABSTRACT FROM AUTHOR]