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Cells exposed to stress factors experience time-dependent variations of metabolite concentration, acting as reliable sensors of the effective concentration of drugs in solution. NMR can detect and quantify changes in metabolite concentration, thus providing an indirect estimate of drug concentration. The quantification of bactericidal molecules released from antimicrobial-treated biomedical materials is crucial to determine their biocompatibility and the potential onset of drug resistance.Real-time NMR measurements of extracellular metabolites produced by bacteria grown in the presence of known concentrations of an antibacterial molecule (irgasan) are employed to quantify the bactericidal molecule released from antimicrobial-treated biomedical devices. Viability tests assess their activity against E. coli and S. aureus planktonic and sessile cells. AFM and contact angle measurements assisted in the determination of the mechanism of antibacterial action.NMR-derived concentration kinetics of metabolites produced by bacteria grown in contact with functionalized materials allows for indirectly evaluating the effective concentration of toxic substances released from the device, lowering the detection limit to the nanomolar range. NMR, AFM and contact angle measurements support a surface-killing mechanism of action against bacteria.The NMR based approach provides a reliable tool to estimate bactericidal molecule release from antimicrobial materials.The novelty of the proposed NMR-based strategy is that it i) exploits bacteria as sensors of the presence of bactericidal molecules in solution; ii) is independent of the chemo-physical properties of the analyte; iii) establishes the detection limit to nanomolar concentrations.

Colloidal semiconductor nanocrystals (NCs) and, recently, nanoplatelets (NPLs), owing to their efficient and narrow-band luminescence, are considered as frontier materials for light-emitting diode (LED) technology. NC-LEDs typically incorporate interfacial layers as charge regulators to ensure charge balancing and high performance. In this Letter, we show the prolongation of the lifetime of multilayer solution-processed NC-LEDs by combining a self-doped conductive conjugated polyelectrolyte and exfoliated molybdenum disulfide (MoS2) flakes as an alternative to PEDOT:PSS. The ink features a neutral pH and a tunable hydrophobicity that mainly results in a remarkable stability of LEDs, using CdSe/CdZnS NPLs.

Se sintetizaron nanopartículas de plata AgNPs a partir de nitrato de plata, empleando borohidruro de sodio como agente reductor y poli(etilendioxitiofeno):poli(estiren sulfonato de sodio), PEDOT:PSS, como estabilizador. Se variaron los siguientes parámetros de síntesis: 1) contenido relativo entre PEDOT y PSS, utilizando tres formulaciones comerciales; y 2) relación molar entre sal de plata y agente reductor. Por espectroscopia UV-Vis, se corroboró la formación de las AgNPs mediante la banda plasmónica a ~ 400 nm, además se observaron cambios espectrales para el PEDOT cuando se utilizan las formulaciones con mayor contenido de PEDOT, y relación sal/agente reductor de ~1, lo cual de acuerdo con los espectros Raman se asocia con un cambio conformacional del PEDOT hacia una estructura más benzenoide. En las demás condiciones, las propiedades espectroscópicas son similares a las de nanopartículas preparadas con puro PSS. Con base en los resultados, se plantea que las AgNPs se estabilizan con el PSS en exceso, afuera de los dominios PEDOT:PSS, cuando la formulación tiene más contenido de PSS o empleando bajas cantidades de NaBH4. Al incrementar el contenido de NaBH4, las AgNPs se forman también adentro de los dominios. El mecanismo de estabilización permite así modular las propiedades ópticas y eléctricas de las NPs.

Colloidal semiconductor nanoplatelets (NPLs) are a subgroup of quantum confined materials that have recently emerged as promising active materials for solution processed light-emitting diodes (LEDs) thanks to their peculiar structural and electronic properties as well as their reduced dimensionality. Nowadays, the conventional structure for NPL-based LEDs makes use of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a hole transporting layer (HTL). This is a well-known conjugated conductive polymer because it leads to high LED efficiency, though it has limited stability in air due to its intrinsic acidity and hygroscopicity. Here, we develop a nanocomposite aqueous ink, obtained by blending commercial PEDOT:PSS with water-based, stable and highly concentrated molybdenum disulfide (MoS2) nanosheets, obtained via liquid phase exfoliation (LPE), which is suitable as a HTL for solution processed NPL-based LEDs. We demonstrate that the MoS2 additive effectively works as a performance booster in unpackaged devices, thereby prolonging the lifetime up to 1000 hours under ambient conditions. Moreover, the addition of MoS2 induces a modification of the anode interface properties, including a change in the work function and a significant enhancement of the permittivity of the HTL.

Conjugated polymers with ionic pendant groups (CPEs) are receiving increasing attention as solution-processed interfacial materials for organic solar cells (OSCs). Various anionic CPEs have been successfully used, on top of ITO (Indium Tin Oxide) electrodes, as solution-processed anode interlayers (AILs) for conventional devices with direct geometry. However, the development of CPE AILs for OSC devices with inverted geometry is an important topic that still needs to be addressed. Here, we have designed three anionic CPEs bearing alkyl-potassium-sulfonate side chains. Their functional behavior as anode interlayers has been investigated in P3HT:PC61BM (poly(3-hexylthiophene): [6,6]-phenyl C61 butyric acid methyl ester) devices with an inverted geometry, using a hole collecting silver electrode evaporated on top. Our results reveal that to obtain effective anode modification, the CPEs’ conjugated backbone has to be tailored to grant self-doping and to have a good energy-level match with the photoactive layer. Furthermore, the sulfonate moieties not only ensure the solubility in polar orthogonal solvents, induce self-doping via a right choice of the conjugated backbone, but also play a role in the gaining of hole selectivity of the top silver electrode.

Polymer solar cells (PSCs) based on non-fullerene acceptors have the advantages of synthetic versatility, strong absorption ability, and high thermal stability. These characteristics result in impressive power conversion efficiency values, but to further push both the performance and the stability of PSCs, the insertion of appropriate interlayers in the device structure remains mandatory. Herein, a naphthalene diimide-based cathode interlayer (NDI-OH) is synthesized with a facile three-step reaction and used as a cathode interlayer for fullerene and non-fullerene PSCs. This cationic polyelectrolyte exhibited good solubility in alcohol solvents, transparency in the visible range, self-doping behavior, and good film forming ability. All these characteristics allowed the increase in the devices’ power conversion efficiencies (PCE) both for fullerene and non-fullerene-based PSCs. The successful results make NDI-OH a promising cathode interlayer to apply in PSCs.

Here, two novel approaches for disassembling epitaxial silicene from the native substrate and transferring onto arbitrary target substrates are presented. From the processing perspective, the two methodologies open up a new route for handling silicene, and in general any epitaxial Xene, in view of establishing reliable process flows for the development of a Xene‐based nanotechnology. Integration of silicene in a back‐gated controlled device architecture is demonstrated and the built up of unique multi‐stack heterostructures between silicene, but potentially every Xene, and other technological relevant materials, like transparent conductive oxides and transition metal dichalcogenides is shown.

Large area molybdenum disulfide (MoS2) monolayers are typically obtained by using perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) as organic seeding promoter in chemical vapor deposition (CVD). However, the influence of the seeding promoter and the involvement of the functional groups attached to the seed molecules on the physical properties of the MoS(2)monolayer are rarely taken into account. Here, it is shown that MoS(2)monolayers exhibit remarkable differences in terms of the electronic polarizability by using two representative cases of seeding promoter, namely, the commercial PTAS and a home-made perylene-based molecule,N,N-bis-(5-guanidil-1-pentanoic acid)-perylene-3,4,9,10-tetracarboxylic acid diimide (PTARG). By thermogravimetric analysis, it is verified that the thermal degradation of the promoters occurs differently at the CVD working condition: with a single detachment of the functional groups for PTAS and with multiple thermal events for PTARG. As a consequence, the promoter-dependent electronic polarizability, derived by free charges trapped in the monolayer, impacts on the photoluminescence emission, as well as on the electrical performances of the monolayer channel in back-gated field-effect transistors. These findings suggest that the modification of the electronic polarizability, by varying the molecular promoter in a pre-growth stage, is a path to engineer the MoS(2)opto-electronic properties.

Interfacial engineering provides an important tool for optimizing the performances of optoelectronic devices. We show that poly[(2,7-(9,9′-dioctyl)fluorene)-alt-(2,7-(9,9′-bis(5″-trimethylammonium bromide)pentyl)fluorene)])], an alcohol-soluble π-conjugated polymer based on polyfluorene backbone and ammonium groups on the alkyl side chains, is capable of modifying the interface between the organic layer and the metal cathode in both organic solar cells and light-emitting diodes based on commercial materials and conventional architectures, improving their performances. The introduction of the cathode interlayer enhances the efficiency of a red-emitting phosphorescent OLED by 15% and decreases its turn-on voltage. The same polymer improves the power conversion efficiency of a PTB7/PC71BM solar cell by 55% and shows a beneficial effect in terms of device stability.

The aqueous processing of hydrophobic conjugated polymers to produce nanoparticles is an emerging technology with wide application in photonic, optoelectronic, biological and medical areas. The insertion of 4VP-based tailored segment in the polymeric backbone prevents the surfactant addition during the aqueous nanoparticle fabrication. Four amphiphilic low band gap rod-coil block copolymers, constituted by a semiconducting rigid block and differing in the coil molecular structure and length, were processed in aqueous medium using the miniemulsion approach without surfactant use. Stable water-processable nanoparticles (WPNPs) suspended in aqueous medium were obtained, and WPNP-based films were deposited. The STEM-EDX analysis revealed the WPNP internal composition. The S-concentration, connected with the rod block location, is higher in the WPNP core, and the C-concentration higher on the WPNP edge when pure 4VP-based coils are present, confirming their surfactant-like role.

Two homologous series of rod-coil block-copolymers, composed by a low band gap rod moiety (poly[2,6-(4,4-bis-(2-ethylhexyl)-4 H -cyclopenta[2,1- b :3.4- b’ ]dithiophene)- alt -4,7-(2,1,3-benzothiadiazole)], PCPDTBT) and a flexible poly(4-vinylpyridine) based polar block, were synthesized by two different approaches. Step Growth-like procedure provided copolymers with longer coil, whilst copolymers with longer rod arise from Chain Growth-like process. Both the series were deeply investigated with different analytical techniques ( 1 H NMR, SEC-DV, and MALDI-TOF MS) in order to prove the coupling process and elucidate the composition of the obtained materials. Chemical composition was evaluated by 1 H NMR analysis. DSC heating traces of rod-coil copolymers synthesized by Step Growth-like route present two well resolved glass transition temperatures corresponding to the rod and coil blocks. The low band-gap rod-coil block copolymers especially these with short coil can find application in hybrid solar cells.

We report on the scanning tunneling microscopy and small-wide angle X-ray scattering and diffraction of four linear and rigid π-conjugated p-phenyleneethynylene (PPE) oligomers. The four compounds possess two dodecanoxy side chains on the central PPE moiety, differ in conjugated length (3 and 5 phenyleneethynylene moieties) and are benzyl, Bz3PEBz, Bz5PEBz, or carboxylic acid, Ac3PEAc, Ac5PEAc, end-capped. We found that in the benzylbenzoate terminated oligomers, a staggered arrangement of molecules is obtained endorsed by the π-π interaction between the benzyls. In contrast, for the carboxylic acid terminated oligomers, a rather linear type arrangement is promoted by the hydrogen bond created between the carboxylic acid groups. In general, all of the molecules form a lamellar like pattern adopting face-on arrangements, where the conjugated backbones are flat-lying on the HOPG surface. The lamella length corresponds to the oligomer conjugation length, while within the lamellae, the calculated distances correspond to the spacing between conjugated backbones with an average value of 2.06 nm, consistent with that found by XRD, SAXS and DFT/def-SVP for the oligomers that self-assemble with the lateral alkyl chains interdigitated. The lack of more dodecanoxy side chains on the rest of the pheneyleneethynylene moieties gives rise to mesoporous type self-assembled monolayers on HOPG.

Starch recovered from an agrifood waste, pea pods, was enzymatically modified and used to prepare cryogels applied as drug carriers. The enzymatic modification of starch was performed using the laccase/(2,2,6,6-tetramethylpiperidin-1-yl)oxyl TEMPO system, at a variable molar ratio. The characterization of the ensuing starches by solution NMR spectroscopy showed partial conversion of the primary hydroxyl groups versus aldehyde and carboxyl groups and successive creation of hemiacetal and ester bonds. Enzymatically modified starch after simple freezing and lyophilization process provided stable and compact cryogels with a morphology characterized by irregular pores, as determined by atomic force (AFM) and scanning electron microscopy (SEM). The application of cryogels as carriers of active molecules was successfully evaluated by following two different approaches of loading with drugs: a) as loaded sponge, by adsorption of drug from the liquid phase, and b) as dry-loaded cryogel, from a dehydration step added to loaded cryogel from route (a). The efficiency of the two routes was studied and compared by determining the drug release profile by proton NMR studies over time. Preliminary results demonstrated that cryogels from modified starch are good candidates to act as drug delivery systems due to their stability and prolonged residence times of loaded molecules, opening promising applications in biomedical and food packaging scenarios.

Three-dimensional bioprinting, thanks to its great versatility, flexibility, perfect reproducibility and high speed, has recently emerged as a promising technology, especially in biological applications, making possible its use in different fields. In fact, synthetic organ manufacturing using natural derived polymers, with mechanical micro-extrusion technology, demonstrated its potential applications in tissue regeneration and vascular reconstruction but processes need to better control high resolution, degradation time and contamination. Here we propose a low cost liquid frozen deposition manufacturing 3D bioprinter with a smart and middle-ware technology, using customized algorithms, in order to support processes for tissue-engineering. We described 46 geometrical parameters in a ultra-defined architecture scaffolds that conserved original characteristics for more than 23 months after rehydration, and evaluated the mechanical characteristics, the surface micro-morphology and the related cell viability. Moreover, we demonstrated that the cells can be entrapped into Bio-Trap in the rehydrated scaffold thickness and can be maintained alive for 3 weeks. With these smart-technologies, it is possible to obtain a first evaluation of different process parameters and scaffold architecture for the fabrication of long-term organoid controlling the full cycle of scaffold fabrication from the biomaterial selection to the final 3D bio-architecture. Statement of significance – Materialia This study has the aim to standardize the comparison and the analysis of the different scaffold's functionalized structure. In fact, the high number of possible functionalizations of dedicated biological structure, needs a structured data scheduling. Thus, this study shows a new method for the implementation of Computer Aided Tissue Engineering (CATE) using 3D bio-printing and smart technology with the aim to develop vertical channels, for the vascularization of the scaffold, and Bio-Traps able to entrap the cells within scaffold's height. This innovative technique, thanks to its flexibility, can support the personalization of high-defined scaffold geometries for in vitro research activities.

In this work a novel combination of side chain functionalities, alkyl-phosphonate (EP) and alkyl-ammonium bromide (NBr) groups, on a polyfluorene backbone (PF-NBr-EP) was studied as cathode interfacial material (CIM) in polymer-based solar cells. The devices were made with a conventional geometry, with PTB7:PC71 BM as active layer and aluminum as metal electrode. The CIM showed good solubility in ethanol and film forming ability onto the active layer so that its deposition could be finely tuned. The interface engineering imparted by this CIM was assessed and discussed through kelvin probe force microscopy (KPFM), impedance spectroscopy, charge recombination and electron transport characterizations. To discriminate between the interfacial modifications imparted by the interlayer and its solvent, we included in this study a surface ethanol treated device. In the optimized conditions an average power conversion efficiency of 7.24% was obtained, which is about 60% higher when compared to devices made with bare Al and 26% when compared to devices made with a standard calcium/aluminum cathode. Besides performances, some insights about the devices shelf life stability are also presented. A good persistency through aging was found for the cathode interfacial engineering capabilities of PF-NBr-EP.

The goal of the paper was to design a new pathway towards eco-materials suitable for CO2 capture, by functionalization of nanoporous chitosan fibers with monoaldehydes via imination. To this end, nanoporous chitosan fibers were prepared by electrospinning and further reacted with furfural. Their morphology was investigated by SEM and AFM microscopies and revealed the formation of a network of nanoporous submicrometric fibers. The successful imination was proved by FTIR, XPS, and NMR spectroscopies. As a proof of concept, the CO2 adsorption isotherms displayed enhanced CO2 adsorption of the furfuryl-imine-chitosan fibers compared to pristine ones, indicating the imination of porous chitosan fibers as a feasible method to new eco-materials for CO2 adsorption.

Water-processable organic nanoparticles (NPs) of semiconducting polymers received wide attention for optoelectronic applications due to their simple fabrication and tunable properties. The NP-based approach is appealing to control the morphology of the active layer in optoelectronic devices, such as organic photovoltaics (OPVs), organic light-emitting diodes, and organic field-effect transistors. The miniemulsion method ensures the stability of the water-suspended NPs using insulating surfactants, lowering the chlorinated solvent use for the active layer fabrication. To gain good performances, the surfactant excess has to be removed at the end of the process. [Mater Today 2016, 19, 533] Here we will present a series of amphiphilic low band gap rod-coil block copolymers (BCPs), constituted by a low band-gap polymer, PCPDTBT as electron donor material, and different poly-4-vinylpyridine (P4VP)-based flexible blocks. We studied the capability of these BCPs, neat or in blend with electron acceptor materials, to assembly NP dispersions in aqueous medium through miniemulsion without surfactants, exploiting the hydrophilic coil behavior and avoiding costly purification steps. The coil block features address the assembly in the obtained NPs, neat and blended with fullerene derivatives, leading to the nano-aggregation in the active layers. The relationship between the nano-aggregation of the NPs and the device performances will be discussed. [Adv Sustain Sys DOI:10.1002/adsu.201700155]

Perylene diimide derivatives containing pendant cysteine residues are subjected to a strong self-assembly onto [1 1 1] Au films due to the presence of thiol functionality. The preparation of two different Au surfaces easies the understanding of both surface packing and morphology of the aggregated ordered films, by means of the combination of X-ray photoelectron spectroscopy, atomic force microscopy, and grazing incident wide X-ray scattering - synchrotron radiation - techniques. A proper correlation of the resulting data, together with conformational calculations - using a detailed molecular modelling - allow supplying a coherent scenario. In particular, isolated ordered pillars upstanding to the substrate plane are detected on native gold surface, while a π-stacked aggregation “unregistered” normally to the film plane is observed when perylene derivatives are grafted onto thermally annealed gold surface. Such a surface organization is expected to be favourable to the charge mobility, therefore its use in organic field effect transistor is envisioned.

Water-processable organic nanoparticles (NPs) of semiconducting polymers received wide attention for optoelectronic applications due to their simple fabrication and tunable properties. The NP-based approach is appealing to control the morphology of the active layer in optoelectronic devices, such as organic photovoltaics (OPVs), organic light-emitting diodes, and organic field-effect transistors. The miniemulsion method ensures the stability of the water-suspended NPs using insulating surfactants, lowering the chlorinated solvent use for the active layer fabrication. To gain good performances, the surfactant excess has to be removed at the end of the process. [Mater Today 2016, 19, 533] Here we will present a series of amphiphilic low band gap rod-coil block copolymers (BCPs), constituted by a low band-gap polymer, PCPDTBT as electron donor material, and different poly-4-vinylpyridine (P4VP)-based flexible blocks. We studied the capability of these BCPs, neat or in blend with electron acceptor materials, to assembly NP dispersions in aqueous medium through miniemulsion without surfactants, exploiting the hydrophilic coil behavior and avoiding costly purification steps. The coil block features address the assembly in the obtained NPs, neat and blended with fullerene derivatives, leading to the nano-aggregation in the active layers. The relationship between the nano-aggregation of the NPs and the device performances will be discussed. [Adv Sustain Sys DOI:10.1002/adsu.201700155]

Here we present for the first time polymer solar cells that incorporate biological material that show state of the art efficiencies in excess of 8%. The performance of inverted polymer solar cells was improved significantly after deposition of ZnO nanoparticles (ZnO-NPs) together with a thin deoxyribonucleic acid nanolayer and used as an electron extraction layer (EEL). The ZnO-NPs/DNA double layer improved the rectifying ratio, shunt resistance of the cells as well as lowering the work function of the electron-collecting contact. Importantly, the ZnO-NPs/DNA bilayer enhanced the power conversion efficiency of cells considerably compared to cells with EELs made of only DNA (improvement of 56% in relative terms) or only ZnO-NPs (improvement of 19% in relative terms) reaching a best power conversion efficiency of 8.5%. The ZnO-NPs/DNA double layer cells also outperformed ones made with one of the most efficient previous synthetic composite EELs (i.e. ZnO/PEIE(poly(ethyleneimine)-ethoxylated)). Since all fabrication procedures were carried out at low (

Opals are photonic structures with applications varying from coatings and pigments to photonics and optical devices. Colloidal self-assembly of polymer-based nanoparticles is a cheap and green method to create opals over large areas: recently, procedures combining co-deposition of crosslinker precursors and other additives with nanoparticle self-assembly have emerged as routes to large-area efficient deposition. We investigate how the presence of some common organic dyes and pigments affects the properties and self assembling behavior of core shell polystyrene particles with a poly(methacrylic acid) shell during horizontal deposition (casting) from water, studying both the variation of particles properties in solution and the structure and properties of the resulting films. The study further includes the effects of a precursor of silica crosslinking (Tetraethoxysilane), and its combination with the same dyes, and we are able to show how interactions starting in the nanoparticles dispersion affect the structure and properties of the crystals. (C) 2015 Elsevier Ltd. All rights reserved.

Core substituted perylene diimides are promising n-type semiconductor materials for organic photovoltaic applications. We have prepared three Donor-Acceptor-Donor perylene diimide molecules, substituted in bay positions with bithiophene, spirobifluorene and bithiophene spirobifluorene groups. These molecules were tested as electron acceptors, in blend with P3HT as donor material, in bulk heterojunction solar cells. The active layers of these devices were optimized by thermal treatment or by the presence of additives and the photovoltaic characteristics were measured. The photovoltaic performances of the three perylene diimides were studied and discussed through absorption and emission spectroscopy characterization, atomic force microscopy morphology study and charge-carrier transport measurements.

A detailed structural and orientational study on thin films of poly([n,n′-bis(2-octyldodecyl)-11naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-12 bithiophene)) (P(NDI2OD-T2)) with low molecular weight is reported. The combination of grazing incidence diffraction with varied depth sensitivity and powder diffraction using synchrotron radiation provide new insights on the unit cell, confirming polymorphic behavior, and configuration ratio, i.e. face- versus edge-on. The effect of thermal treatment on microstructure is also presented. Insights of the macromolecule configuration, specifically the reciprocal position of bis-dicarboximide and bi-thiophene residues, are derived from simulation of 2D images based on reliable models.

Water-based nanoparticles (NPs) of semiconducting polymers received considerable attention for optoelectronic and biological applications due to their simple preparation method, and their tunable optical properties.1 NPs are appealing for optoelectronic devices such as organic photovoltaic devices (OPVs),2 organic light-emitting diodes (OLEDs),3 and organic field-effect transistors (OFETs)4 to control the morphology of the active layer that plays a crucial role in the device performance. The NPs dispersion can be obtained through the miniemulsion method, using great amount of surfactants to ensure NPs stability. This approach allows for lowering the chlorinated solvent amount used in the active layer fabrication reducing the environmental payback of the devices, but to achieve good performances the excess of surfactant has to be removed at the end of the process.5 Amphiphilic block copolymers (BCPs) are a powerful tool to produce nanostructured or supramolecular objects with enhanced properties for electronics, optoelectronics, sensors and biotechnological applications because of their capability to self-assembly, influenced by the physico-chemical differences between the blocks, including the relative block length, block polarity, volume fraction, chain flexibility, etc.6 PCPDTBT-b-P4VP is an amphiphilic rod-coil BCP constituted by a low band-gap copolymer, PCPDTBT as the rigid segment, and tailored segments of poly-4-vinylpyridine (P4VP). The rod block was studied as donor material in hybrid and organic devices, whilst P4VP is able to interact with acceptor materials, as fullerene derivatives.7 Taking advantage of hydrophilic behavior of the coil, we studied the capability of PCPDTBT-b-P4VP to form NPs dispersion in aqueous medium through miniemulsion method, neat or in blend with fullerene derivatives, without use of surfactants avoiding purification steps. The NPs were optically, morphologically (AFM, TEM, Synchrotron XRD) and electrically characterized, showing suitable properties for the preparation of active layers and they were tested in eco-friendly NP-based OPVs with efficiency reaching over 2%.

The morphology control of the active layer is essential to obtain high efficiency in organic solar cells (OSCs).1 Even on laboratory scale the active layer optimization requires large amount of chlorinated aromatic solvents, that are harmful for environment and human health, and strictly regulated by laws, restricting their industrial development so far.2 Recently the use of water-processable nanoparticles (WPNPs), consisting of a blend of a semiconducting polymer and a fullerene derivative (e.g. PC61BM), emerged as a sustainable approach to control of the morphology of the active layer and to reduce the use of chlorinated aromatic solvents, leading to eco-friendly efficient devices,3 and paving the way for a new technological implementation of OSCs. Here we reported on the application of an amphiphilic low band gap rod-coil block copolymer (PCPDTBT-b-P4VP) for the preparation of WPNPs, through an adapted miniemulsion method (see the figure),4 and their application to the fabrication of standard WPNP-based OSCs with a power conversion efficiency of 2.53%.5 References 1. Polymers 2014, 6, 2832; 2. Environ. Health Persp. 2010, 118, 1355; Adv. Energy Mater. 2011, 1, 68; 3. Adv. Mater. 2014, 26, 6653; 4. Adv. Mater. 2002, 14, 651; 5. S. Zappia, G. Scavia, A.M. Ferreti, U. Giovanella, V.Vohra, S. Destri, submitted to Advanced Sustainable Systems. Acknowledgments: Associazione Italiana Scienza e Tecnologia delle Macromolecole (AIM), PRIN Project 2012A4Z2RY-AQUA-SOL, Regione Lombardia Project 2016 "i-ZEB".

Conjugated dye-intercalated fluoromica hybrids involving three different cationic organic dyes, i.e. oxazine, rhodamine and ter-fluorene derivatives, have been characterized by synchrotron X-ray diffraction (XRD) in combination with optical spectroscopy. The results show the tunability of the dye packing, hence of the absorption and emission properties, as a function of both type and amount of intercalated molecule. Suitable molecular models compatible with XRD findings, accounting for the observed optical behavior, are proposed and discussed.

Even if organic solar cells (OSCs) could have many advantages with respect to silicon devices, their industrial implementation is still limited by some relevant drawbacks. Besides reduced stability and efficiency, the commonly used techniques in laboratory are not suitable for application on industrial scale. To improve efficiency of the devices, morphology control during the active layer deposition results a key point for achieving high efficiency in OSCs. Optimized interpenetrating networks of donor and acceptor materials, nanoscale phase separation, and vertical percolation pathways are essential for effective separation, transport, and collection of the charges. Usually this control is obtained through the use of mixed organic solvents for the active layer deposition (chlorinated and/or aromatic solvents), the use of additives or post-fabrication treatments, as thermal or solvent annealing.1 The preparation of water-processable nanoparticle (NP) dispersions of semiconducting polymers recently emerged as an elegant technique to control morphology at nanoscale. At the same time, it allows lowering chlorinated solvents waste, thus reducing the environmental payback of energy obtained from OPVs and paving the way for the industrial application. The NPs dispersion can be obtained through the miniemulsion method that requires use of a great amount of surfactant agents to ensure NPs stability, the excess of surfactant has to be removed at the end of the process through dialysis.2 Rod-coil block copolymers (BCPs) can be powerful tools to achieve ideal morphologies because of their self-assembly capability that is strictly connected to the length of the two blocks and to their physical-chemical properties.3 We report on the PV application of rod-coil BCPs, PCPDTBT-b-P4VP, constituted by a low band-gap copolymer, PCPDTBT as the rigid segment, studied as donor material in hybrid and organic devices,4 and tailored segments of poly-4-vinylpyridine (P4VP) able to interact with acceptor materials commonly used in OPVs,5 as fullerene derivatives. Taking advantage of hydrophilic behavior of their flexible moiety, these amphiphilic rod-coil BCPs were used for preparing NPs in blend with PCBM, through miniemulsion method in aqueous medium without use of surfactants, thus avoiding dialysis purification. The NPs were fully morphologically and electrically characterized, showing suitable properties for PV application. The PCBM:BCP blend NPs dispersed in aqueous medium were used for the preparation of efficient eco-friendly OSCs, reaching a power conversion efficiency over 2%, near the best result reported for the same system studied in chlorinated solvents.6 1. Polymers 2014, 6, 2832 2. Nature Mat 2003, 2, 408 3. Mater Sci Eng R 2008, 62, 37 4. ACS Nano 2013, 7, 4846; Chem Commun 2013, 49, 8602 5. Eur Pol J 2014, 60, 222 6. Adv Mater 2010, 22, 367

Low band gap (LGB) polymers are characterized by a band gap below 2 eV, thus absorbing light with wavelengths longer than 620 nm.1 Their polymeric chains are constituted by the alternating electron-rich and electron-poor units. LGB were widely studied in last decades to improve the efficiency of organic photovoltaics (OPVs) due to a better overlap with the solar spectrum, leading to a maximum photon harvesting in the devices.2 Combining this intrinsic feature with the appealing capability of the block copolymers (BCPs) to nanosegregate, we obtained new rod-coil BCPs with a rigid segment constituted by a LBG polymer and a flexible one made up of poly-4vinylpyridine (P4VP) or a segmented poly(styrene-random-4-vynilpyridine). P4VP allows the interaction with commonly used acceptor materials for organic or hybrid PVs.3 Two strategies were applied to the preparation of the target polymers, combining a nitroxide-mediated radical polymerization and a Suzuki polycondensation. A step-growth like approach, consisting in the synthesis, purification, and characterization of the two blocks separately, that were then coupled through a further Suzuki reaction, and a chain-growth like method, constituted by the early synthesis of a properly activated rigid macroiniziator for the subsequent polymerization of the flexible block. The two pathways led to two series of materials differing particularly in controlling the coil block length. Due to the strong differences in chemical-physical properties of the two blocks, the purification and characterization procedures of the obtained materials have to be ad hoc tailored for a correct determination of their molecular structure, crossing the data from different techniques.4 These materials showed, together with their self-assembling capability, interesting features exploitable for photovoltaic applications. Some of the obtained materials were successfully employed as nanostructuring additive in hybrid solar cells, with inorganic semiconductor nanoparticles of CdSe, as acceptor.5 New trials are in progress for the realization of composites nanostructures with PCBM in aqueous medium, to be used as active layers in bulk heterojunctions solar cells. Preliminary results of these studies will be presented. Acknowledgments: research supported by Project AQUA-SOL - Aqueous processable polymer solar cells: from materials to photovoltaic modules (PRIN 2012A4Z2RY) 1 Bundgaard, Krebs, Solar En Mater & Solar Cells 91 (2007) 954. 2 Jayakannan, Van Hal, Janssen , J. Pol. Sci. A Pol. Chem 40 (2002) 251. 3 Di Mauro, Toscanini, Piovani, Samperi, Curri, Corricelli, Comparelli, Agostiano, Destri, Striccoli, Eur Pol J 72 (2014) 222. 4 Zappia, Mendichi, Battiato, Scavia, Mastria, Samperi, Destri, Polymer 80 (2015) 245; Samperi, Montaudo Battiato, Zappia, Destri, paper submitted. 5 Zappia, Destri, Striccoli, Curri, Di Mauro, Zoobia, Maruccio, Rizzo, Mastria, Adv. Sci. Technol. 93 (2014) 235; Zappia, Di Mauro, Mastria, Rizzo, Curri, Striccoli, Destri, accepted Eur. Pol J. (2016) doi:10.1016/j.eurpolymj.2016.03.021

In this article, we report a detailed study of surface modification of magnetite nanoparticles by means of three different grafting agents, functional for the preparation of magnetic polymer brushes. 3-Aminopropyltriethoxysilane (APTES), 3-chloropropyltriethoxysilane (CPTES), and 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane (CTCS) were chosen as grafting models through which a wide range of polymer brushes can be obtained. By means of accurate thermogravimetric analysis a good control over the amount of immobilized molecules is achieved, and optimal operating conditions for each grafting agent are consequently determined. Graft densities ranging from approximately 4 to 7 molecules per nm2 are obtained, depending on the conditions used. In addition, the surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) carried out with CTCS-coated nanoparticles is presented as an example of polymer brushes, leading to a well-defined and dense polymeric coating of around 0.6 PMMA chains per nm2.

An exemplary system suitable for optoelectronics applications, i.e. poly(3-hexylthiophene), hereinafter P3HT, deposited by spin casting onto silicon substrates functionalised by three selected molecules and then properly annealed, has been examined. Grazing Incidence X-ray Scattering (GIXS) measurements have been performed with 4-circle diffractometer, allowing for a fine control of sample axes movement. By choosing different grazing incident angles, diffraction patterns from different layers of polymeric thin films have been recorded. Both in-plane and out-of-plane geometries have been combined in order to obtain complementary structural information. In this way structural and orientational differences of the polymer along with the film thickness (⩽50 nm) have been highlighted. For all P3HT films spun on functionalized Si wafer, macromolecular layers close to the substrate surface give some evidence of higher order and orientation than those outmost the surface, and this behaviour is pronounced to a different extent depending on the functionalized molecules used. Contrariwise P3HT layers deposited onto bare Si wafer display reduced orientation and decreased crystallite size, especially at buried interface.

The preparation of water-processable nanoparticles (NPs) of polymer semiconductors assembled using an amphiphilic rod-coil block copolymer (BCP), and their application to active layer sustainable fabrication of organic photovoltaic devices are reported. The hydrophobic rod is a p-type semiconductor, while the hydrophilic coil is a short chain of poly-4-vinylpyridine strongly interacting with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). Through miniemulsion technique stable water-suspended blend NPs are obtained, avoiding nonconducting surfactant use. The amphiphilic BCP fulfills a dual function, as surfactant for stabilizing the blend NPs and as electron donor material in the active layer. After mild annealing of obtained films, blend NPs interconnect with each other forming compact and uniform layers with adequate morphology for efficient charge percolation to the electrodes. Space-charge limited hole mobility of ?5 × 10-3 cm2 V-1 s-1 in BCP-only NP films annealed at 120 °C (corresponding to a tenfold increase in mobility as compared to the p-type semiconductor films spin-coated from chlorinated solvents) indicates strong p-p interactions in the self-assembled NPs. Blend NPs were covered with thin PC61BM layer and used as active layers in photovoltaic devices displaying high photocurrents (11.5 mA cm-2) and average power conversion efficiency of 2.53% after annealing at 90 °C.

A detailed structural and morphological study on bulk poly(3-hexylthiophene), having high regioregularity (about 98%) and molecular weight of 16 kDa, has been performed. The combination of wide- and small-angle X-ray diffraction techniques, for the first time on bulk semicrystalline conjugated polymer, allowed to get insight on the structural features of poly(3-hexylthiophene), subjected to different thermal treatments. The evolution or the periodicity, the crystallite dimension and defects, as a function of the annealing were determined. Fibrillar organization, evidenced atomic force microscopy, results in the coexistence of disordered areas where fibrils are randomly oriented and ordered regions where fibrils are organized into stacks, with periodic pattern matching the periodicity determined by X-ray scattering.

Magnetic Co50Pt50 films few nanometers thick have been deposited by Pulsed Laser Deposition on MgO (100) single crystal at a deposition temperature of 600 °C and then annealed “in situ” for different time. A very thin Pt underlayer (< 2 nm) with an incomplete coverage is used as a possible template to favour the growth of isolated grains of the magnetic layer. The correlation between the structural, microstructural and magnetic properties has been studied as a function of the annealing time. In particular, measurements gave evidence of the presence of two competing effects of the annealing treatment: formation of hard fct-CoPt phase and thermal diffusion process between Pt and CoPt layer resulting in a reduction of the crystallographic order.

Rod-coil block copolymers (BCPs) can be powerful tools to achieve ideal morphologies in bulk heterojunction (BHJ) solar cells, which require an interprenetrating network between donor and acceptor material at the nanoscale. Their self-assembly behavior is strictly connected to the lenght of the two blocks and to the synthetic route to their preparation. Step-growth strategy implies the preparation of two blocks properly functionalized to covalently react. Chain-growth method consists, instead, of the preparation of a macroinitiator activated with an end-group directly capable to promote the polymerization of the second block or to be converted into a functional group able to do it. Many conjugated polymers were used as rigid moiety in BCPs for solar cells. For the fist time, we used a low band-gap copolymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3.4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) intesively studied as donor material into hybrid solar cells (HSCs). Poly-4-vynilpyridine (P4VP), was selected as flexible segment that allows the interaction with acceptor materials, in particular semiconducting inorganic nanoparticles, as CdSe nanocristals (NCs). Exploiting both synthetic approaches, with a proper combination of Suzuki Coupling and Nitroxide-Mediated Radical Polymerization (NMRP), two different series of BCPs were obtained, deeply investigated to elucidate their molecular structure, and then tested into the active layer of HSCs, as nanostructuring compatibilizer.

The investigation of the electrical properties of Co-doped ZnO thin films provides two unexpected results: a decrease of the electrical conductivity and the contemporary occurrence of a reduction of conductivity and of an enhancement of ferromagnetic order. The former result is surprising since Zn atoms are replaced with iso-valent Co atoms. The latter finding questions previously suggested beneficial effects of n-type doping on the ZnO:Co magnetic behavior. While morphological and structural characterization permits us to exclude an influence of the morphology and of the presence of Co metal or Co-oxide phases on present experimental findings, with the aid of first-principles electronic structure calculations, we propose a qualitative picture which can explain in a coherent way both the changes in conductivity and ferromagnetic behavior ensuing from the Co doping and the above-mentioned, beneficial effects of n-type doping. This journal is © The Royal Society of Chemistry.

A combined ultrahigh vacuum scanning tunneling microscopy (STM-UHV) and energy dispersive X-ray diffractometry/reflectometry (EDXD/EDXR) study of the evolution of face-centered cubic (fcc) Pt layer growth on MgO(100) by pulsed laser deposition as a function of the process parameters such as deposition temperature and deposition duration has been carried out. The aim of this study is to define the best experimental conditions to obtain a controlled film deposition selective on the Pt growth direction (either [111] or [002]). The evolution of the Pt surface morphology as a function of the deposition temperature (T(dep)) from 300 to 700 degrees C has been studied with STM and ED techniques. Results show that the Pt surface, characterized at T(dep) = 300 degrees C by a 3D island morphology, evolves at higher temperatures to a morphology in which the original islands coexist with a distribution of orthogonal 2D stripes. The two features can be associated with the [111] and [002] Pt growth directions of the fcc phase, respectively. For T(dep) = 700 degrees C, the island morphology of the (111) face completely disappears, while the merging process of the (002) stripes reaches completion. The evolution of the morphology at T(dep) = 600 degrees C as a function of the deposition time and thickness has then been studied with STM-UHV, revealing an initial growth of mosaic-like 3D islands. These independent islands, already interconnected, expand along two orthogonal directions and, for longer deposition times, lead to the texture of orthogonal stripes. The EDXR characterization providing the morphological parameters of the films, i.e., thickness and roughness, confirms the above observation and quantifies the effect of such morphological changes on the surface roughness of the Pt film, an important parameter for applications of Pt films as underlayer in magnetic recording media.

An STM-UHV study of the deposition of titanium bis-phthalocyanine under high vacuum (UHV) conditions on two different substrates such as GaAs(1 0 0)- β 2-(2 × 4) and highly oriented pyrolytic graphite (HOPG) has been carried out. An STM spectroscopic analysis on the local density of states has been also performed. In the case of GaAs as substrate, the STM images show that the molecules align themselves preferentially along the dimer rows, typical of the (2 × 4) reconstruction, thus revealing the fundamental role of the interaction between the molecule and the reconstructed substrate in orienting the adsorbed molecules. In the case of HOPG, the images indicate the formation of irregular channels thus suggesting an auto-assembling of the molecules between themselves rather than a strong interaction with the substrate, as in the GaAs case.

A comparative study of gold deposition on the GaAs(0 0 1)-β2(2×4) surface based on scanning tunneling microscopy (STM)–ultra high vacuum (UHV) and Car–Parrinello calculations has been carried out. The theoretical results show that the preferential reactive sites of an isolated Au adatom on the GaAs surface drive a self-organizing process of further Au adatoms onto the surface, thus determining an Au clusterization onto the two-As-dimer cell. On the other hand, STM–UHV images reveal, for Au depositions 1 ML suggests that gold clusterizes into 3D clusters rather than forming a 2D layer.

We examined the thermal treatment stabilization processes in SnO/sub 2/-based thin films for gas-sensing applications in order to understand their influence on structural properties and possible relations with functional behavior of the sensors. The films of SnO/sub 2/ were deposited by magnetron sputtering, following the rules of the rheothaxial growth and thermal oxidation (RGTO) technique and annealed in humid synthetic air at 600/spl deg/C. Afterward, a thin overlayer of gold or platinum was deposited on the oxidized films. The samples were characterized soon after catalyzer deposition and after one-hour aging process at 400/spl deg/C, in order to evaluate stabilization process influence as a function of catalyzer. X-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM) demonstrated that a short aging affects the microstructure of gold-catalyzed samples, while it does not influence platinum catalyzed ones. The results of the microstructural characterization were confirmed by electrical measurements of gas-sensitivity: the short-aging influences the stability of gas-sensing parameters only in gold-catalyzed samples.