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Grazing Incidence X-ray Diffraction (GIXD) is a widely used characterization technique, applied for the investigation of the structure of thin films. As far as organic films are concerned, the confinement of the film to the substrate results in anisotropic 2-dimensional GIXD patterns, such those observed for polythiophene-based films, which are used as active layers in photovoltaic applications. Potential malfunctions of the detectors utilized may distort the quality of the acquired images, affecting thus the analysis process and the structural information derived. Motivated by the success of Morphological Component Analysis (MCA) in image processing, we tackle in this study the problem of recovering the missing information in GIXD images due to potential detector’s malfunction. First, we show that the geometrical structures which are present in the GIXD images can be represented sparsely by means of a combination of over-complete transforms, namely, the curvelet and the undecimated wavelet transform, resulting in a simple and compact description of their inherent information content. Then, the missing information is recovered by applying MCA in an inpainting framework, by exploiting the sparse representation of GIXD data in these two over-complete transform domains. The experimental evaluation shows that the proposed approach is highly efficient in recovering the missing information in the form of either randomly burned pixels, or whole burned rows, even at the order of 50% of the total number of pixels. Thus, our approach can be applied for healing any potential problems related to detector performance during acquisition, which is of high importance in synchrotron-based experiments, since the beamtime allocated to users is extremely limited and any technical malfunction could be detrimental for the course of the experimental project. Moreover, the non-necessity of long acquisition times or repeating measurements, which stems from our results adds extra value to the proposed approach.

The response of sands stabilized with colloidal silica aqueous gel is examined in the laboratory. The role of colloidal silica on subsequent sand behaviour is examined with the aid of monotonic loading tests to establish the mechanical response and the resistance of the treated sand to liquefaction. It appears that depending on the loading conditions while the strength of the treated sand is enhanced, its stiffness may reduce and its compressibility increase. This contradictory behaviour is investigated on the basis of an extended database including direct shear, triaxial and normal compression tests. [ABSTRACT FROM AUTHOR]

Active hydroponic substrates that stimulate on demand the plant growth have not been demonstrated so far. Here, we developed the eSoil, a low-power bioelectronic growth scaffold that can provide electrical stimulation to the plants' root system and growth environment in hydroponics settings. eSoil's active material is an organic mixed ionic electronic conductor while its main structural component is cellulose, the most abundant biopolymer. We demonstrate that barley seedlings that are widely used for fodder grow within the eSoil with the root system integrated within its porous matrix. Simply by polarizing the eSoil, seedling growth is accelerated resulting in increase of dry weight on average by 50% after 15 d of growth. The effect is evident both on root and shoot development and occurs during the growth period after the stimulation. The stimulated plants reduce and assimilate NO 3 - more efficiently than controls, a finding that may have implications on minimizing fertilizer use. However, more studies are required to provide a mechanistic understanding of the physical and biological processes involved. eSoil opens the pathway for the development of active hydroponic scaffolds that may increase crop yield in a sustainable manner., Competing Interests: Competing interests statement:The authors declare no competing interest.

Increasing plants' photosynthetic efficiency is a major challenge that must be addressed in order to cover the food demands of the growing population in the changing climate. Photosynthesis is greatly limited at the initial carboxylation reaction, where CO 2 is converted to the organic acid 3-PGA, catalyzed by the RuBisCO enzyme. RuBisCO has poor affinity for CO 2 , but also the CO 2 concentration at the RuBisCO site is limited by the diffusion of atmospheric CO 2 through the various leaf compartments to the reaction site. Beyond genetic engineering, nanotechnology can offer a materials-based approach for enhancing photosynthesis, and yet, it has mostly been explored for the light-dependent reactions. In this work, we developed polyethyleneimine-based nanoparticles for enhancing the carboxylation reaction. We demonstrate that the nanoparticles can capture CO 2 in the form of bicarbonate and increase the CO 2 that reacts with the RuBisCO enzyme, enhancing the 3-PGA production in in vitro assays by 20%. The nanoparticles can be introduced to the plant via leaf infiltration and, because of the functionalization with chitosan oligomers, they do not induce any toxic effect to the plant. In the leaves, the nanoparticles localize in the apoplastic space but also spontaneously reach the chloroplasts where photosynthetic activity takes place. Their CO 2 loading-dependent fluorescence verifies that, in vivo , they maintain their ability to capture CO 2 and can be therefore reloaded with atmospheric CO 2 while in planta . Our results contribute to the development of a nanomaterials-based CO 2 -concentrating mechanism in plants that can potentially increase photosynthetic efficiency and overall plants' CO 2 storage.

Plant processes, ranging from photosynthesis through production of biomaterials to environmental sensing and adaptation, can be used in technology via integration of functional materials and devices. Previously, plants with integrated organic electronic devices and circuits distributed in their vascular tissue and organs have been demonstrated. To circumvent biological barriers, and thereby access the internal tissue, plant cuttings were used, which resulted in biohybrids with limited lifetime and use. Here, we report intact plants with electronic functionality that continue to grow and develop enabling plant-biohybrid systems that fully maintain their biological processes. The biocatalytic machinery of the plant cell wall was leveraged to seamlessly integrate conductors with mixed ionic-electronic conductivity along the root system of the plants. Cell wall peroxidases catalyzed ETE-S polymerization while the plant tissue served as the template, organizing the polymer in a favorable manner. The conductivity of the resulting p(ETE-S) roots reached the order of 10 S cm -1 and remained stable over the course of 4 weeks while the roots continued to grow. The p(ETE-S) roots were used to build supercapacitors that outperform previous plant-biohybrid charge storage demonstrations. Plants were not affected by the electronic functionalization but adapted to this new hybrid state by developing a more complex root system. Biohybrid plants with electronic roots pave the way for autonomous systems with potential applications in energy, sensing and robotics.

A series of well-defined (polyisoprene) 2 (polystyrene), I 2 S, single graft copolymers with similar total molecular weights but different compositions, f PS , were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene- b -polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene) 2 (polyisoprene), S 2 I, graft copolymer was also studied, and the comparison with the results of the corresponding I 2 S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I 2 S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends.

The presence of excited-states and charge-separated species was identified through UV and visible laser pump and visible/near-infrared probe femtosecond transient absorption spectroscopy in spin coated films of poly[ N -9″-heptadecanyl-2,7-carbazole- alt -5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) nanoparticles and mesoparticles. Optical gain in the mesoparticle films is observed after excitation at both 400 and 610 nm. In the mesoparticle film, charge generation after UV excitation appears after around 50 ps, but little is observed after visible pump excitation. In the nanoparticle film, as for a uniform film of the pure polymer, charge formation was efficiently induced by UV excitation pump, while excitation of the low energetic absorption states (at 610 nm) induces in the nanoparticle film a large optical gain region reducing the charge formation efficiency. It is proposed that the different intermolecular interactions and molecular order within the nanoparticles and mesoparticles are responsible for their markedly different photophysical behavior. These results therefore demonstrate the possibility of a hitherto unexplored route to stimulated emission in a conjugated polymer that has relatively undemanding film preparation requirements.

The pursuit for novelty in the field of (bio)electronics demands for new and better-performing (semi)conductive materials. Since the discovery of poly(3,4-ethylenedioxythiophene) (PEDOT), the ubiquitous golden standard, many studies have focused on its applications but only few on its structural modification and/or functionalization. This lack of structural variety strongly limits the versatility of PEDOT, thus hampering the development of novel PEDOT-based materials. In this paper, we present a short and simple strategy for introducing an aldehyde functionality in thiophene-based semiconducting polymers. First, through a two-step synthesis, an EDOT-aldehyde derivative was prepared and polymerized, both chemically and electrochemically. Next, to overcome the inability of thiophene-aldehyde to be polymerized by any means, we synthesized a trimer in which thiophene-aldehyde is enclosed between two EDOT groups. The successful chemical and electrochemical polymerization of this new trimer is presented. The polymer suspensions were characterized by ultraviolet-visible-near-infrared spectroscopy, while the corresponding films were characterized by Fourier transform infrared and four-point-probe conductivity measurements. Afterward, insoluble semiconducting films were formed by using ethylenediamine as a cross-linker, demonstrating in this way the suitability of the aldehyde group for the easy chemical modification of our material. The efficient reactivity conferred by aldehyde groups was also exploited for grafting fluorescent polyamine nanoparticles on the film surface, creating a fluorescent semiconducting polymer film. The films prepared by electropolymerization, as shown by means of a sonication test, exhibit strong surface adhesion on pristine indium tin oxide (ITO). This property paves the way for the application of these polymers as conductive electrodes for interfacing with living organisms. Thanks to the high reactivity of the aldehyde group, the aldehyde-bearing thiophene-based polymers prepared herein are extremely valuable for numerous applications requiring the facile incorporation of a functional group on thiophene, such as the functionalization with labile molecules (thermo-, photo-, and electro-labile, pH sensitive, etc.).

We investigated the impact of singly occupied molecular orbital (SOMO) energy on the n-doping efficiency of benzimidazole derivatives. By designing and synthesizing a series of new air-stable benzimidazole-based dopants with different SOMO energy levels, we demonstrated that an increase of the dopant SOMO energy by only ∼0.3 eV enhances the electrical conductivity of a benchmark electron-transporting naphthalenediimide-bithiophene polymer by more than 1 order of magnitude. By combining electrical, X-ray diffraction, and electron paramagnetic resonance measurements with density functional theory calculations and analytical transport simulations, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, and crystallinity of the doped polymer as a function of the dopant SOMO energy. Our findings strongly indicate that charge and energy transport are dominated by the (relative) position of the SOMO level, whereas morphological differences appear to play a lesser role. These results set molecular-design guidelines for next-generation n-type dopants.

The photophysics of water and propan-1-ol suspensions of poly [N-9"-heptadecanyl-2,7-carbazole- alt -5,5-(4,7-di-2-thienyl-2',1',3'- benzothiadiazole)] (PCDTBT) nanoparticles and mesoparticles has been studied by ultrafast spectroscopy. High molar mass polymer (HMM > 20 kg/mol) forms nanoparticles with around 50 nm diameter via mini-emulsion post-polymerization, while low molar mass (LMM < 5 kg/mol) polymer prepared by dispersion polymerization results in particles with a diameter of almost one order of magnitude larger (450 ± 50 nm). In this study, the presence of excited-states and charge separated species was identified through UV pump and visible/near-infrared probe femtosecond transient absorption spectroscopy. A different behavior for the HMM nanoparticles has been identified compared to the LMM mesoparticles. The nanoparticles exhibit typical features of an energetically disordered conjugated polymer with a broad density of states, allowing for delayed spectral relaxation of excited states, while the mesoparticles show a J-aggregate-like behavior where interchain interactions are less efficient. Stimulated emission in the red-near infrared region has been found in the mesoparticles which indicates that they present a more energetically ordered system.

The fabrication of organic solar cells from aqueous dispersions of photoactive nanoparticles has recently attracted the interest of the photovoltaic community, since these dispersions offer an eco-friendly solution for the fabrication of solar cells, avoiding the use of toxic solvents. In this work, aqueous dispersions of pure poly[n-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) nanoparticles, as well as of composite PC 71 BM:PCDTBT nanoparticles, are prepared using the nanoprecipitation postpolymerization method. These dispersions are subsequently used to form the active layer of organic photovoltaic cells. Thin films of PC 71 BM and PCDTBT are obtained by spray deposition of the nanoparticles' dispersions, and are characterized using a combination of spectroscopic and microscopic techniques. Photovoltaics that incorporate these active layers are fabricated thereafter. The impact of the annealing temperature and of the composition of the active layer on the efficiency of the solar cells is studied., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A recently synthesized self-doped conducting oligomer, salt of bis[3,4-ethylenedioxythiophene]3thiophene butyric acid, ETE-S, is a novel promising material for green energy applications. Recently, it has been demonstrated that it can polymerize in vivo, in plant systems, leading to a formation of long-range conducting wires, charge storage and supercapacitive behaviour of living plants. Here we investigate the morphology of ETE-S combining the experimental characterisation using Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) and atomistic molecular dynamics (MD) simulations. The GIWAXS measurements reveal a formation of small crystallites consisting of π-π stacked oligomers (with the staking distance 3.5 Å) that are further organized in h00 lamellae. These experimental results are confirmed by MD calculations, where we calculated the X-ray diffraction pattern and the radial distribution function for the distance between ETE-S chains. Our MD simulations also demonstrate the formation of the percolative paths for charge carriers that extend throughout the whole structure, despite the fact that the oligomers are short (6-9 rings) and crystallites are thin along the π-π stacking direction, consisting of only two or three π-π stacked oligomers. The existence of the percolative paths explains the previously observed high conductivity in in vivo polymerized ETE-S. We also explored the geometrical conformation of ETE-S oligomers and the bending of their aliphatic chains as a function of the oligomer lengths.

A major issue that inhibits the large-scale fabrication of organic solar modules is the use of chlorinated solvents considered to be toxic and hazardous. In this work, composite particles of poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and [6,6]-phenyl C71 butyric acid methyl ester (PC 71 BM) were obtained in water from a versatile and a ready-to-market methodology based on postpolymerization miniemulsification. Depending on the experimental conditions, size-controlled particles comprising both the electron donor and the electron acceptor were obtained and characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle neutron scattering (SANS), UV-visible absorption, and fluorescence spectroscopy. Intimate mixing of the two components was definitely asserted through PCDTBT fluorescence quenching in the composite nanoparticles. The water-based inks were used for the preparation of photovoltaic active layers that were subsequently integrated into organic solar cells.

Unlabelled: Due to the rising need for clean energy, thermoelectricity has raised as a potential alternative to reduce dependence on fossil fuels. Specifically, thermoelectric devices based on polymers could offer an efficient path for near-room temperature energy harvesters. Thus, control over thermoelectric properties of conducting polymers is crucial and, herein, the structural, electrical and thermoelectric properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin films doped with p-toluenesulfonate (Tos) molecules were investigated with regards to thin film processing., Pedot: Tos thin films were prepared by in-situ polymerization of (3,4-ethylenedioxythiophene) monomers in presence of iron(III) p-toluenesulfonate with different co-solvents in order to tune the film structure. While the Seebeck coefficient remained constant, a large improvement in the electrical conductivity was observed for thin films processed with high boiling point additives. The increase of electrical conductivity was found to be solely in-plane mobility-driven. Probing the thin film structure by Grazing Incidence Wide Angle X-ray Scattering has shown that this behavior is dictated by the structural properties of the, Pedot: Tos films; specifically by the thin film crystallinity combined to the preferential edge-on orientation of the PEDOT crystallites. Consequentially enhancement of the power factor from 25 to 78.5 μW/mK(2) has been readily obtained for, Pedot: Tos thin films following this methodology.

The addition of a block copolymer to the polymer/fullerene blend is a novel approach to the fabrication of organic solar cells. The block copolymer (P3HT-b-P4VP) is used as nanostructuring agent in the active layer. A significant enhancement of the cell efficiency is observed, in correlation with morphology control, both before (as-cast) and after the annealing process., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)