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1.
Chemistry ; 29(14): e202203441, 2023 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-36477929

RESUMO

Naphthalene tetracarboxylic diimides (NDIs) are highly promising air-stable n-type molecular semiconductor candidates for flexible and cost-effective organic solar cells and thermoelectrics. Nonetheless, thermal and polymorphic stabilities of environmentally stable NDIs in the low-to-medium temperature regime (<300 °C) remain challenging properties. Structural, thermal, spectroscopic, and computational features of polyfluorinated NDI-based molecular solids (with up to 14 F atoms per NDI molecule) are discussed upon increasing the fluorination level. Slip-stacked arrangement of the NDI cores with suitable π-π stacking and systematically short interplanar distances (<3.2 Å) are found. All these materials exhibit superior thermal stability (up to 260 °C or above) and thermal expansion coefficients indicating a response compatible with flexible polymeric substrates. Optical bandgaps increase from 2.78 to 2.93 eV with fluorination, while LUMO energy levels decrease down to -4.37 eV, as shown per DFT calculations. The compounds exhibit excellent solubility of 30 mg mL-1 in 1,4-dioxane and DMF.

2.
Nanotechnology ; 34(29)2023 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-37019100

RESUMO

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices.

3.
Langmuir ; 33(45): 12859-12864, 2017 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-29028341

RESUMO

Ferroelectric molecular compounds present great advantages for application in electronics because they combine high polarization values, comparable to those of inorganic materials, with the flexibility and low-cost properties of organic ones. However, some limitations to their applicability are related to the high crystallinity required to deploy ferroelectricity. In this article, highly ordered ferroelectric patterned thin films of diisopropylammonium bromide have been successfully fabricated by a lithographically controlled wetting technique. Confinement favors the self-organization of ferroelectric crystals, avoiding the formation of polymorphs and promoting the long-range orientation of crystallographic axes. Patterned structures present high stability, and the polarization can be switched to be arranged in stable domain pattern for application in devices.

4.
Chemistry ; 21(30): 10666-70, 2015 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-26095511

RESUMO

We report herein an efficient, fast, and simple synthesis of an imine-based covalent organic framework (COF) at room temperature (hereafter, RT-COF-1). RT-COF-1 shows a layered hexagonal structure exhibiting channels, is robust, and is porous to N2 and CO2 . The room-temperature synthesis has enabled us to fabricate and position low-cost micro- and submicropatterns of RT-COF-1 on several surfaces, including solid SiO2 substrates and flexible acetate paper, by using lithographically controlled wetting and conventional ink-jet printing.

5.
Chemphyschem ; 16(16): 3379-84, 2015 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-26342212

RESUMO

The amorphous aggregation of Aß1-40 peptide is addressed by using micromolding in capillaries. Both the morphology and the size of the aggregates are modulated by changing the contact angle of the sub-micrometric channel walls. Upon decreasing the hydrophilicity of the channels, the aggregates change their morphology from small aligned drops to discontinuous lines, thereby keeping their amorphous structure. Aß1-40 fibrils are observed at high contact angles.


Assuntos
Peptídeos beta-Amiloides/química , Fragmentos de Peptídeos/química , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Biomarcadores/líquido cefalorraquidiano , Dimetilpolisiloxanos/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Varredura por Sonda , Fragmentos de Peptídeos/metabolismo
6.
Sci Technol Adv Mater ; 16(6): 065008, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27877850

RESUMO

We report on the effects of low energy ion implantation on thin films of pentacene, carried out to investigate the efficacy of this process in the fabrication of organic electronic devices. Two different ions, Ne and N, have been implanted and compared, to assess the effects of different reactivity within the hydrocarbon matrix. Strong modification of the electrical conductivity, stable in time, is observed following ion implantation. This effect is significantly larger for N implants (up to six orders of magnitude), which are shown to introduce stable charged species within the hydrocarbon matrix, not only damage as is the case for Ne implants. Fully operational pentacene thin film transistors have also been implanted and we show how a controlled N ion implantation process can induce stable modifications in the threshold voltage, without affecting the device performance.

7.
Nano Lett ; 13(8): 3643-7, 2013 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-23879239

RESUMO

The applications of organic semiconductors in complex circuitry such as printed CMOS-like logic circuits demand miniaturization of the active structures to the submicrometric and nanoscale level while enhancing or at least preserving the charge transport properties upon processing. Here, we addressed this issue by using a wet lithographic technique, which exploits and enhances the molecular order in polymers by spatial confinement, to fabricate ambipolar organic field effect transistors and inverter circuits based on nanostructured single component ambipolar polymeric semiconductor. In our devices, the current flows through a precisely defined array of nanostripes made of a highly ordered diketopyrrolopyrrole-benzothiadiazole copolymer with high charge carrier mobility (1.45 cm(2) V(-1) s(-1) for electrons and 0.70 cm(2) V(-1) s(-1) for holes). Finally, we demonstrated the functionality of the ambipolar nanostripe transistors by assembling them into an inverter circuit that exhibits a gain (105) comparable to inverters based on single crystal semiconductors.


Assuntos
Nanoestruturas/química , Polímeros/química , Estrutura Molecular , Semicondutores
8.
J Mater Chem B ; 12(8): 2083-2098, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38284627

RESUMO

Calcium phosphates are widely studied in orthopedics and dentistry, to obtain biomimetic and antibacterial implants. However, the multi-substituted composition of mineralized tissues is not fully reproducible from synthetic procedures. Here, for the first time, we investigate the possible use of a natural, fluorapatite-based material, i.e., Lingula anatina seashell, resembling the composition of bone and enamel, as a biomaterial source for orthopedics and dentistry. Indeed, thanks to its unique mineralization process and conditions, L. anatina seashell is among the few natural apatite-based shells, and naturally contains ions having possible antibacterial efficacy, i.e., fluorine and zinc. After characterization, we explore its deposition by ionized jet deposition (IJD), to obtain nanostructured coatings for implantable devices. For the first time, we demonstrate that L. anatina seashells have strong antibacterial properties. Indeed, they significantly inhibit planktonic growth and cell adhesion of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The two strains show different susceptibility to the mineral and organic parts of the seashells, the first being more susceptible to zinc and fluorine in the mineral part, and the second to the organic (chitin-based) component. Upon deposition by IJD, all films exhibit a nanostructured morphology and sub-micrometric thickness. The multi-doped, complex composition of the target is maintained in the coating, demonstrating the feasibility of deposition of coatings starting from biogenic precursors (seashells). In conclusion, Lingula seashell-based coatings are non-cytotoxic with strong antimicrobial capability, especially against Gram-positive strains, consistently with their higher susceptibility to fluorine and zinc. Importantly, these properties are improved compared to synthetic fluorapatite, showing that the films are promising for antimicrobial applications.


Assuntos
Exoesqueleto , Anti-Infecciosos , Animais , Biomimética , Flúor , Materiais Revestidos Biocompatíveis/farmacologia , Antibacterianos/farmacologia , Apatitas/farmacologia , Zinco/farmacologia , Odontologia
9.
J Phys Chem C Nanomater Interfaces ; 128(13): 5408-5417, 2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38595774

RESUMO

Heat is an inexhaustible source of energy, and it can be exploited by thermoelectronics to produce electrical power or electrical responses. The search for a low-cost thermoelectric material that could achieve high efficiencies and can also be straightforwardly scalable has turned significant attention to the halide perovskite family. Here, we report the thermal voltage response of bismuth-based perovskite derivates and suggest a path to increase the electrical conductivity by applying chalcogenide doping. The films were produced by drop-casting or spin coating, and sulfur was introduced in the precursor solution using bismuth triethylxanthate. The physical-chemical analysis confirms the substitution. The sulfur introduction caused resistivity reduction by 2 orders of magnitude, and the thermal voltage exceeded 40 mV K-1 near 300 K in doped and undoped bismuth-based perovskite derivates. X-ray diffraction, Raman spectroscopy, and grazing-incidence wide-angle X-ray scattering were employed to confirm the structure. X-ray photoelectron spectroscopy, elemental analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed to study the composition and morphology of the produced thin films. UV-visible absorbance, photoluminescence, inverse photoemission, and ultraviolet photoelectron spectroscopies have been used to investigate the energy band gap.

10.
Cryst Growth Des ; 23(8): 5801-5811, 2023 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-37547884

RESUMO

Scleractinia coral skeleton formation occurs by a heterogeneous process of nucleation and growth of aragonite in which intraskeletal soluble organic matrix molecules, usually referred to as SOM, play a key role. Several studies have demonstrated that they influence the shape and polymorphic precipitation of calcium carbonate. However, the structural aspects that occur during the growth of aragonite have received less attention. In this research, we study the deposition of calcium carbonate on a model substrate, silicon, in the presence of SOM extracted from the skeleton of two coral species representative of different living habitats and colonization strategies, which we previously characterized. The study is performed mainly by grazing incidence X-ray diffraction with the support of Raman spectroscopy and electron and optical microscopies. The results show that SOM macromolecules once adsorbed on the substrate self-assembled in a layered structure and induced the oriented growth of calcite, inhibiting the formation of vaterite. Differently, when SOM macromolecules were dispersed in solution, they induced the deposition of amorphous calcium carbonate (ACC), still preserving a layered structure. The entity of these effects was species-dependent, in agreement with previous studies. In conclusion, we observed that in the setup required by the experimental procedure, the SOM from corals appears to present a 2D lamellar structure. This structure is preserved when the SOM interacts with ACC but is lost when the interaction occurs with calcite. This knowledge not only is completely new for coral biomineralization but also has strong relevance in the study of biomineralization on other organisms.

11.
ACS Omega ; 8(46): 43651-43663, 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-38027374

RESUMO

Naphthalene tetracarboxylic diimides (NDIs), possessing low-lying and tunable LUMO levels, are of wide interest for their aptitude to provide cost-effective, flexible, and environmentally stable n-type organic semiconductors through simple solution processing. NDI-based aromatic hydrazidimides are herein studied in relation to their chemical and environmental stability and as spin-coated stable thin films. In the case of the pentafluorinated residue, these were found to be crystalline, highly oriented, and molecularly flat (roughness = 0.3 nm), based on optical and atomic force microscopy, X-ray diffraction in specular and grazing incidence geometry, and X-ray reflectivity measurements. A new polymorph, previously undetected during the isolation of bulk powders or in their controlled thermal treatments, is found in the thin film and was metrically and structurally characterized from 2D GIWAXS patterns (monoclinic, P2/c, a = 17.50; b = 4.56; c = 14.24 Å; ß = 84.8°). This new thin-film phase, TF-F5, is formed no matter whether silicon, glass, or polymethylmethacrylate substrates are used, thus opening the way to the preparation of solution-grown flexible semiconducting films. The TF-F5 films exhibit a systematic and rigorous molecular alignment with both orientation and packing favorable to electron mobility (µ = 0.02 cm2 V-1 s-1). Structural and morphological differences are deemed responsible for the absence of measurable conductivity in thin films of polyfluorinated analogues bearing -CF3 residues on the hydrazidimide aromatic rings.

12.
Langmuir ; 27(7): 4076-81, 2011 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-21366277

RESUMO

We present a study on thin deposits and patterning of 1-D spin-crossover compounds Fe(II)-(L)(2)H](ClO(4))(3)·MeOH [L = 4'-(4'''-pyridyl)-1,2':6'1''-bis- (pyrazolyl) pyridine] (1) that exhibit a reversible, thermally driven spin transition at room temperature. Micrometric rodlike crystals of 1 on silicon surfaces are achieved by drop casting and solvent annealing. We observed that the crystallinity of thin deposits and spin-transition properties critically depends on the deposition procedure. Furthermore, we proved processability and patterning using unconventional wet lithography that reduces the crystallite formation time by 1 order of magnitude. Thin deposits of 1 were characterized by atomic force microscopy, polarized optical microscopy and X-rays, and the switching properties were characterized by Raman spectroscopy.

13.
Int J Mol Sci ; 12(9): 5719-35, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22016622

RESUMO

A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiO(x) substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiO(x) substrates with the selective arrangement of molecular ultra-thin film. The former is used to fabricate silicon oxide arrays of parallel lines of 400 nm in width over an area of 1 cm(2). Selective growth arises from the interplay between kinetic growth parameters and preferential interactions with the patterned surface. The result is an ultra-thin film of organic molecules that is conformal to the features of the fabricated motives.


Assuntos
Compostos Heterocíclicos de 4 ou mais Anéis/química , Nanoestruturas/química , Óxidos/química , Compostos de Silício/química , Tiofenos/química , Cristalografia por Raios X , Estimulação Elétrica , Microscopia de Força Atômica , Oxirredução , Espalhamento a Baixo Ângulo , Propriedades de Superfície , Termodinâmica , Difração de Raios X
14.
ACS Appl Mater Interfaces ; 13(49): 58301-58308, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34851625

RESUMO

Methylammonium lead tribromide (MAPbBr3) perovskite single crystals demonstrate to be excellent direct X-ray and gamma-ray detectors with outstanding sensitivity and low limit of detection. Despite this, thorough studies on the photophysical effects of exposure to high doses of ionizing radiation on this material are still lacking. In this work, we present our findings regarding the effects of controlled X-ray irradiation on the optoelectronic properties of MAPbBr3 single crystals. Irradiation is carried out in air with an imaging X-ray tube, simulating real-life application in a medical facility. By means of surface photovoltage spectroscopy, we find that X-ray exposure quenches free excitons in the material and introduces new bound excitonic species. Despite this drastic effect, the crystals recover after 1 week of storage in dark and low humidity conditions. By means of X-ray photoelectron spectroscopy, we find that the origin of the new bound excitonic species is the formation of bromine vacancies, leading to local changes in the dielectric response of the material. The recovery effect is attributed to vacancy filling by atmospheric oxygen and water.

15.
Nanomaterials (Basel) ; 11(10)2021 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-34685211

RESUMO

In this study, the structure and morphology, as well as time, ultraviolet radiation, and humidity stability of thin films based on newly developed 1D (PRSH)PbX3 (X = Br, I) pseudo-perovskite materials, containing 1D chains of face-sharing haloplumbate octahedra, are investigated. All films are strongly crystalline already at room temperature, and annealing does not promote further crystallization or film reorganization. The film microstructure is found to be strongly influenced by the anion type and, to a lesser extent, by the DMF/DMSO solvent volume ratio used during film deposition by spin-coating. Comparison of specular X-ray diffraction and complementary grazing incidence X-ray diffraction analysis indicates that the use of DMF/DMSO mixed solvents promotes the strengthening of a dominant 100 or 210 texturing, as compared the case of pure DMF, and that the haloplumbate chains always lie in a plane parallel to the substrate. Under specific DMF/DMSO solvent volume ratios, the prepared films are found to be highly stable in time (up to seven months under fluxing N2 and in the dark) and to highly moist conditions (up to 25 days at 78% relative humidity). Furthermore, for representative (PRSH)PbX3 films, resistance against ultraviolet exposure (λ = 380 nm) is investigated, showing complete stability after irradiation for up to 15 h at a power density of 600 mW/cm2. These results make such thin films interesting for highly stable perovskite-based (opto)electronic devices.

16.
Nanoscale ; 12(3): 1432-1437, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31912835

RESUMO

Herein, we propose an easy and practical method for the fabrication of highly ordered supramolecular structures. The proposed approach combines fractional precipitation and wet lithography, to obtain a spatially-defined pattern of submicrometric structures with a high molecular order of poly(3-hexylthiophene). The process is demonstrated by XRD, confocal and time-resolved spectroscopy and by the performance of an effective field effect transistor.

17.
Chem Commun (Camb) ; 56(11): 1689-1692, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31942908

RESUMO

Here we applied a novel concept of "sublimation-aided nanostructuring" to control the polymorphism of a model material. The process exploits fractional precipitation as a tool for crystallisation in confinement using a templating agent that sublimes away from the system at the end of the process.

18.
Nat Commun ; 10(1): 5750, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31848336

RESUMO

Metal halide perovskites have emerged as promising photovoltaic materials, but, despite ultralow thermal conductivity, progress on developing them for thermoelectrics has been limited. Here, we report the thermoelectric properties of all-inorganic tin based perovskites with enhanced air stability. Fine tuning the thermoelectric properties of the films is achieved by self-doping through the oxidation of tin (ΙΙ) to tin (ΙV) in a thin surface-layer that transfers charge to the bulk. This separates the doping defects from the transport region, enabling enhanced electrical conductivity. We show that this arises due to a chlorine-rich surface layer that acts simultaneously as the source of free charges and a sacrificial layer protecting the bulk from oxidation. Moreover, we achieve a figure-of-merit (ZT) of 0.14 ± 0.01 when chlorine-doping and degree of the oxidation are optimised in tandem.

19.
J Am Chem Soc ; 130(4): 1177-82, 2008 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-18181619

RESUMO

Conductive wires of sub-micrometer width made from platinum-carbonyl clusters have been fabricated by solution-infilling of microchannels as in microinject molding in capillaries (MIMIC). The process is driven by the liquid surface tension within the micrometric channels followed by the precipitation of the solute. Orientation of supramolecular crystalline domains is imparted by the solution confinement combined with unidirectional flow. The wires exhibit ohmic conductivity with a value of 0.2 S/cm that increases, after thermal decomposition of the platinum-carbonyl cluster precursor to Pt, to 35 S/cm.

20.
ACS Nano ; 11(2): 2000-2007, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28117966

RESUMO

Achieving nanoscale control over the crystalline structure and morphology of electroactive polymer films and the possibility to transfer them onto any solid substrate are important tasks for the fabrication of high-performance organic/polymeric field-effect transistors (FETs). In this work, we demonstrate that ultrathin active layers preassembled at the water/air interface can possess high, anisotropic, and substrate-independent mobility in polymer FETs. By exploiting a modified approach to the Langmuir-Schaeffer technique, we self-assemble conjugated polymers in fibrillar structures possessing controlled thickness, nanoscale structure, and morphology; these highly ordered nanofibrils can be transferred unaltered onto any arbitrary substrate. We show that FETs based on these films possess high and anisotropic hole mobility approaching 1 cm2 V-1 s-1 along the nanofibrils, being over 1 order of magnitude beyond the state-of-the-art for Langmuir-Schaefer polymer FETs. Significantly, we demonstrate that the FET performances are independent of the chemical nature and dielectric permittivity of the substrate, overcoming a critical limit in the field of polymer FETs. Our method allows the fabrication of ultrathin films for low-cost, high-performance, transparent, and flexible devices supported on any dielectric substrate.

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