Three-dimensional (3D) fibrous networks based on metal oxides were obtained by a bio-inspired approach: the replication of an ecological daily-waste, the eggshell membrane (ESM). The biomorphic ...process consists in the immersion of the ESM into aqueous solutions containing the metal salt precursors followed by the calcination of the metal ions impregnated ESM. Biomorphic ZnO, CuO and ZnO–CuO composite networks were obtained, their morphological, structural, compositional, optical, photocatalytical and electrical properties being evaluated. The scanning electron microscopy investigations proved that the hierarchical structure of the original organic template is perfectly replicated into inorganic architectures consisting of interconnected fibers containing metal oxide nanoparticles as building blocks. The photocatalytical properties of the metal oxide networks under solar simulator irradiation were tested through the degradation of methylene blue. Using Si/SiO2 patterned with interdigitated metallic electrodes as substrates during the calcination step, the electrical properties of the self-contacted metal oxide networks were investigated. Thus, by replicating the unique architecture of the ESM, 3D metal oxide interwoven meshwork can be easily developed for various applications in fields such as photocatalysis, sensing, optoelectronic devices, etc.
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•3D fibrous networks based on ZnO, CuO and ZnO–CuO were obtained by replicating the eggshell membranes.•Networks were formed by interconnected fibers containing metal oxide nanoparticles as building blocks.•Metal oxide networks were featured by the typical structure and optical signatures of the two components.•Biomorphic networks induce the MB photodegradation under solar simulation irradiation.•I–V properties of the self-contacted networks were studied using Ti/Pt interdigitated electrodes.
Large scale ZnO nanowire arrays were grown directly on zinc foils using the thermal oxidation in air method. The X-ray diffraction and reflectance investigations confirm that the as-grown nanowires ...properties are typical for ZnO having a hexagonal wurtzite crystalline structure and band-gap values between 3.2 and 3.3eV. The scanning electron microscopy images prove that the density and the dimensions (diameter and length) of the ZnO nanowires can be tuned by controlling the oxidation temperature. Wettability studies reveal in the case of Zn foils a hydrophilic behavior with high water droplet adhesion which is transformed into a superhydrophobic one with low water droplet adhesion after the foils' surfaces are covered with ZnO nanowires. Obtaining functional surfaces with such interesting wetting properties using a simple, inexpensive and highly reproducible thermal oxidation in air technique is very attractive for anticorrosion coatings and self-cleaning applications.
•ZnO nanowire arrays were grown directly on zinc foils by thermal oxidation in air.•ZnO nanowires show a hexagonal wurtzite structure and Eg values of 3.2-3.3 eV.•Density and dimensions of ZnO nanowires are modified with oxidation temperature.•Zn foils reveal a hydrophilic behavior with high water droplet adhesion.•ZnO nanowires exhibit a superhydrophobic behavior with low water droplet adhesion.
Environmentally-friendly bio-organic materials have become the centre of recent developments in organic electronics, while a suitable interfacial modification is a prerequisite for future ...applications. In the context of researches on low cost and biodegradable resource for optoelectronics applications, the influence of a 2D nanostructured transparent conductive electrode on the morphological, structural, optical and electrical properties of nucleobases (adenine, guanine, cytosine, thymine and uracil) thin films obtained by thermal evaporation was analysed. The 2D array of nanostructures has been developed in a polymeric layer on glass substrate using a high throughput and low cost technique, UV-Nanoimprint Lithography. The indium tin oxide electrode was grown on both nanostructured and flat substrate and the properties of the heterostructures built on these two types of electrodes were analysed by comparison. We report that the organic-electrode interface modification by nano-patterning affects both the optical (transmission and emission) properties by multiple reflections on the walls of nanostructures and the electrical properties by the effect on the organic/electrode contact area and charge carrier pathway through electrodes. These results encourage the potential application of the nucleobases thin films deposited on nanostructured conductive electrode in green optoelectronic devices.
•Organic heterostructures prepared by MAPLE having a large absorbtion domain.•Photogeneration process is evidenced in the structure with ZnPc:TPyP mixed layer.•An increase in current value is ...observed in the structure with MgPc:TPyP mixed layer.
Heterostructures based on zinc phthalocyanine (ZnPc), magnesium phthalocyanine (MgPc) and 5,10,15,20-tetra(4-pyrydil)21H,23H-porphine (TPyP) were deposited on ITO flexible substrates by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. Organic heterostructures containing (TPyP/ZnPc(MgPc)) stacked or (ZnPc(MgPc):TPyP) mixed layers were characterized by X-ray diffraction-XRD, photoluminescence-PL, UV–vis and FTIR spectroscopy. No chemical decomposition of the initial materials was observed. The investigated structures present a large spectral absorption in the visible range making them suitable for organic photovoltaics applications (OPV). Scanning electron microscopy-SEM and atomic force microscopy-AFM revealed morphologies typical for the films prepared by MAPLE. The current–voltage characteristics of the investigated structures, measured in dark and under light, present an improvement in the current value (∼3 order of magnitude larger) for the structure based on the mixed layer (Al/MgPc:TPyP/ITO) in comparison with the stacked layer (Al/MgPc//TPyP/ITO). A photogeneration process was evidenced in the case of structures Al/ZnPc:TPyP/ITO with mixed layers.
ZnO crystallites were grown by electroless deposition on poly(methyl methacrylate) (PMMA) fiber mats prepared by an electrospinning technique. The electroless deposition involves three steps: ...sensitization, activation and deposition, which were performed by subsequently dipping the PMMA fiber mats in the appropriate solutions. After the deposition the PMMA fibers are uniformly coated with ZnO prisms which show hexagonal wurtzite structure and optical signatures (band-gap value and emission bands) typical for this semiconductor. By combining electroless deposition and electrospinning, different semiconductor coated polymer fibers can be obtained for a wide range of applications. Both methods are appropriate for large scale production, being scalable, cheap, efficient and suitable for large-area covering techniques.
•ZnO-coated PMMA fibers were prepared by combining two low cost and scalable techniques: electrospinning and electroless deposition.•PMMA fibers were uniformly coated with ZnO prisms shaped crystallites.•ZnO prisms show a hexagonal wurtzite structure and optical signatures typical for this semiconductor (band-gap value and emission bands).
In:ZnO (IZO) thin films were deposited on flexible plastic substrates by pulsed laser deposition (PLD) method. The obtained layers present adequate optical and electrical properties competitive with ...those based on indium tin oxide (ITO). The figure of merit (9 × 10
−3
Ω
−1
) calculated for IZO layers demonstrates that high quality coatings can be prepared by this deposition technique. A thermal annealing (150 °C for 1 h) or an oxygen plasma etching (6 mbar for 10 min.) were applied to the IZO layers to evaluate the influence of these treatments on the properties of the transparent coatings. Using vacuum evaporation, organic heterostructures based on cooper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) were deposited on the untreated and treated IZO layers. The optical and electrical properties of the heterostructures were investigated by UV–Vis, FTIR and current–voltage (
I
–
V
) measurements. For the heterostructure fabricated on IZO treated in oxygen plasma, an improvement in the current value with at least one order of magnitude was evidenced in the
I
–
V
characteristics recorded in dark conditions. Also, an increase in the current value for the heterostructure deposited on untreated IZO layer can be achieved by adding an organic layer such as tris-8-hydroxyquinoline aluminium (Alq
3
).
Organic heterostructures based on zinc phthalocyanine (ZnPc) and perylene tetracarboxylic dianhydride (PTCDA) were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique on ...conductive flexible substrate (ITO/PET) in three configurations: ZnPc/PTCDA (stacked layers), ZnPc:PTCDA (blend) and ZnPc/ZnPc:PTCDA/PTCDA. The effect of the configuration on the optical and electrical properties of the obtained heterostructures was investigated. For all heterostructures was observed an improved optical absorption in visible domain. The
I
–
V
characteristics recorded under illumination, revealed higher short circuit current (
I
SC
) values for the ZnPc:PTCDA and ZnPc/ZnPc:PTCDA/PTCDA structures in comparison with that of the ZnPc/PTCDA structure. The results proved that by MAPLE can be obtained flexible organic heterostructures (in different configurations) with properties adequate for applications in flexible electronics and solar cell fields.
•Organic multilayer based on arylenevinylene oligomers and Alq3 were fabricated by MAPLE on ITO electrodes.•The photoluminescence measurements revealed the emission bands characteristic for the ...oligomers and Alq3 meridional isomer.•MAPLE heterostructures exhibited a good injector contact behavior.•Current in ITO/P78/Alq3/Al heterostructure significantly increases with the increase of organic layer thickness.
Organic heterostructures were fabricated by matrix assisted pulsed laser evaporation (MAPLE) method using arylenevinylene oligomers based on triphenylamine (P78)/carbazole (P13) group and tris(8-hydroxyquinolinato)aluminum salt (Alq3). Optical properties of the organic multilayer structures were characterized by spectroscopic techniques: FTIR, UV–vis and photoluminescence (PL). A good transparency (over 60%) was remarked for the structures with two organic layers in the 550–800nm range. Photoluminescence (PL) spectra proved that the emission characteristics of the materials have been preserved. I–V characteristics of (ITO/oligomer/Alq3/Al and ITO/Alq3/Al) heterostructures were symmetrically while rectifying properties of these heterostructures have not been observed. A comparison between the heterostructures made of layers with different thickness reveals that the higher current (8×10−6A at 1V) was obtained for the ITO/P78/Alq3/Al heterostructure, which is characterized by a larger thickness of the double organic layer. AFM measurements revealed a similar topography while RMS values of the reported structures depend on the organic material.
•New arylene based polymers layers have been prepared by MAPLE.•The polymers show good absorption in the blue-green region of the spectrum.•The morphology of polymers layers is characterized by large ...globules.•The best photovoltaic effect is achieved in the glass/ITO/PEDOT-PSS/AMC16/Al structure.
This paper presents some studies about the preparation by matrix-assisted pulsed laser evaporation (MAPLE) technique of heterostructures with single layer of arylene based polymer, polyN-(2-ethylhexyl)2.7-carbazolyl vinylene/AMC16 and polyN-(2-ethylhexyl)2.7-carbazolyl 1.4-phenylene ethynylene/AMC22, and with layers of these polymers mixed with Buckminsterfullerene/C60 in the weight ratio of 1:2 (AMC16:C60) and 1:3 (AMC22:C60). The deposited layers have been characterized by spectroscopic (UV-Vis-NIR, PL, FTIR) and microscopic (SEM, AFM) methods. The effect of the polymer particularities on the optical and electrical properties of the structures based on polymer and polymer:C60 mixed layer has been analyzed. The study of the electrical properties has revealed typical solar cell behavior for the heterostructure prepared by MAPLE on glass/ITO/PEDOT-PSS with AMC16, AMC22 and AMC22:C60 layer, confirming that this method is adequate for the preparation of polymeric and mixed active layers for solar cells applications. The highest photovoltaic effect was shown by the solar cell structure realized with single layer of AMC16 polymer: glass/ITO/PEDOT-PSS/AMC16/Al.
Styrene, methyl methacrylate and glycidyl methacrylate vinyl monomers were grafted onto chitosan by surfactant-free emulsion copolymerization using potassium persulfate as initiator. The grafted ...compounds were characterized by X-ray diffraction, FTIR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and zeta potential measurements. X-ray diffraction showed changes in the crystallinity pattern of chitosan after the copolymerization reaction. Evidence of grafting was confirmed by FTIR spectroscopy. From zeta potential measurements it is found that the surfaces of graft copolymers latex particles have positive charges resulting from the cationic chitosan molecules. The morphology evaluated by SEM, TEM and AFM proves that in the absence of chitosan, latexes of vinyl homopolymers contain quasi-monodispersed spheres with average diameter of about 400 nm or 250 nm while the graft copolymers latexes are formed by clustered irregular beads with average diameter around 100 nm.
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