Thanks to the commercial success of organic light-emitting diodes, organic electronics is now much more than just a niche alternative to traditional electronics. However, other types of devices based on organic semiconductors (OSCs) are still far from market readiness. A key limitation is that, in thin-film form, OSCs exhibit a high level of structural disorder. Of all strategies for growing films of OSCs, those relying on organic epitaxy yield films whose properties most closely resemble those of single crystals. Yet, this comes at a cost: conventional substrates for epitaxial growth are incompatible with practical device integration. To overcome this issue, we introduce a transfer printing method capable of relocating epitaxially grown films of OSCs from their native substrates to target, device-compatible ones. We demonstrate the feasibility of this approach by transferring highly crystalline rubrene films─grown via organic molecular beam epitaxy and characterized by coherently oriented, micrometer-scale domains and single-crystal-like optical response─from amino acid single crystals to technologically relevant substrates. Notably, morphology, optical characteristics, and photoluminescence dynamics of the films are fully retained following transfer.

Anion Exchange Membrane Water Electrolyzers (AEM-WE) are a promising technology for green hydrogen production. Their development into commercial devices is however hindered by the low AEM durability in alkaline environment. Poly (aryl piperidinium)s (PAPs) AEMs are perhaps the most stable class of AEMs due to the combination of heteroatom-free aromatic backbone and piperidinium cation. Previous works showed the benefits arising from copolymerization of n-methyl-piperidone with trifluoroacetophenone; lower swelling ratio and better mechanical properties are achieved maintaining hydroxide conductivity above 100 mS cm- 1. Despite these results, limited attention has been devoted to this chemistry. In this work we propose a further engineering step through a block copolymerization of the two monomers. A full characterization of AEMs is provided. Block copolymers achieved high conductivity of 130 mS cm- 1 with a very small swelling ratio (7 % @ 80 degrees C). We report a complete WE cell test of these copolymers. Block copolymers-based AEMs reach a current density of 2.5 A cm-2 (2.2 V, 60 degrees C). Random copolymers-based AEMs are more durable, showing no current density decrease in a cell test of 1500 h (1.8 V, 60 degrees C).

Incorporation of lanthanide ions into polymers via rare-earth organic complexes poses the issue of the interaction between the polymer matrix and lanthanide compounds, which can significantly influence both the rare-earth functional properties and the structural features of the matrix. This work investigates the synthesis of europium-containing poly (L-lactic acid) (PLLA) microspheres through an oil-in-water emulsion of PLLA and europium (III) acetylacetonate hydrate dissolved in dichloromethane and water containing poly (vinyl alcohol). The synthesis was conducted at various temperature-from 20 degrees C to 80 degrees C, including conditions above the PLLA glass transition. Results from X-ray diffraction and Raman scattering give evidence of higher crystallinity in Eumodified PLLA microspheres than in undoped PLLA, while differential scanning calorimetry indicates that Eu addition hinders PLLA chain mobility with a resulting decrease in PLLA melt crystallization ability. Insights into the incorporation mechanisms of Eu3+ in the microspheres were provided by photoluminescence, scanning-electron-microscopy, micro-computed-tomography, X-ray fluorescence, and infrared spectroscopy. The analysis shows that Eu3+ complexes enter the polymer structure by interacting with PLLA chains, modifying the local environment of the lanthanide ions. These findings finally provide a new basis for designing tailored synthesis methods for specific applications.

A novel starch-based ether bearing cinnamyl functionalities, conferring photo-crosslinking properties, is synthesised by reaction with cinnamyl chloride in the presence of sodium hydroxide. Natural yuca was selected as a sustainable source of starch. Three different molar equivalents of reagents are used, affording starch-cinnamyl ethers with different degrees of substitution, ranging from 0.09 to 1.24, as determined by liquid phase nuclear magnetic resonance (NMR). The double bonds in the cinnamyl moieties show reactivity towards photodimerization upon irradiation at 254 nm, affording a novel cross-linked bio-inspired polymer. The formation of the covalent ether linkage and the [2+2] cycloaddition of the cinnamyl units are confirmed by a combination of spectroscopic techniques, including solid state NMR. The materials are further characterized by gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and X-ray diffraction analysis (XRD). Starch-cinnamyl ethers with a DS of 0.09 are water soluble, and suitable for the preparation of transparent films potentially exploitable for biodegradable packaging materials.

The optimization of radiation transfer in a mixed culture of purple phototrophic bacteria (PPB) inside a photobioreactor (PBR) is crucial for maximizing growth efficiency and resource recovery. In this study, the optical behavior of PPB mixed cultures was characterized from 300 nm to 1100 nm at different incident light intensities of 10 W center dot m- 2 , 20 W center dot m-2, 40 W center dot m-2, and 60 W center dot m- 2 , and at different biomass concentrations. Experimental data were processed via empirical and Monte Carlo methods to determine the optical properties. Various models, namely the Beer-Lambert law, the two-flux approximation model, and computational fluid dynamics (CFD) simulations, were then applied to describe the radiation transfer inside the PBR. Among the most relevant results, the adaptation of absorption peaks as a function of light intensity was observed. Moreover, the scattering effect was found to be non-negligible, characterized by a strong non-isotropic nature. Although the scattering effect was significant, the results showed that the Beer-Lambert law can effectively describe the light attenuation profiles, resulting in irrelevant errors in calculating the light intensity at each layer of the PBR compared to the two-flux approximation model and CFD simulations, in turn characterized by higher computational costs. However, simpler models could lead to higher values for the local volumetric rate of photon absorption along different layers, especially at lower concentrations. Finally, the results suggest that flat-plate PBRs illuminated from both sides can be an effective solution for PPB systems compared to raceway ponds, mainly due to the enhanced two-sided short-path light penetration.

Perovskite solar cells (PSCs) have burst into photovoltaic (PV) research, revolutionising it and demonstrating that they can achieve performances comparable to technologies already on the market. Despite that, the major limitation of PSCs' commercialisation is their poor environmental stability. Inorganic carriers transporting materials have gained attention for enhancing PSCs' durability due to their superior stability and non-hygroscopic nature. Among them, kesterite Cu2ZnSnS4 (CZTS) is a promising inorganic hole transporting material (HTM) thanks to its optimal electronic properties, non-toxic, abundant elements, and simple solution deposition methods. Herein, the effect on the stability of inverted PSCs employing CZTS nanoparticles (NPs) as HTM is investigated by X-ray photoelectron and ultraviolet photoelectron spectroscopy, together with steady-state and time-resolved photoluminescence spectroscopies. Special attention was given to the alteration in the PV performances over time of the CZTS-based device compared to a control device with a common organic HTM. The enhanced stability of the CZTS NPs-based devices in opposition to degradation of the devices with a [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer as HTM was demonstrated through solar simulator measurements and external quantum efficiency. The efficiency of a CZTS-based p-i-n PSC increased by 34% after three weeks, while the efficiency of the organic HTM-based device decreased by 16% during the same period. Furthermore, CZTS-based PSCs showed a drop-in efficiency of 80% after four days under a humidity test at 70% RH, while the efficiency of the organic HTM-based devices dropped by 80% after two days under the same conditions. Moreover, analysis of the photoluminescence spectra reveals no modification of the CZTS-based PSCs.

Crystalline rubrene (RUB) with the orthorhombic structure can be regarded as a workhorse in organic optoelectronics. So far, however, its great potential for device integration has been held back by the struggle to obtain high-quality and photo-oxidation-resistant RUB thin films. Here, we propose an effective strategy to obtain homogeneous, highly crystalline, and oriented RUB thin films, which relies on the spontaneous amorphous-to-crystal transition driven by organic epitaxy occurring at room temperature in vacuum; this crucial process dictates the final morphological, structural, and optoelectronic properties of the film. To probe the kinetics of the transition, we combine ex situ analysis via polarized optical spectroscopy and atomic force microscopy with a photoluminescence investigation carried out in situ, based on monitoring the efficiency of the singlet fission process typical of crystalline RUB. Building on the insights gained, we tune the thin film growth and post-growth parameters to obtain centimeter-scale, highly homogeneous and crystalline RUB thin films, consisting of several mu m-sized and coherently oriented domains, featuring oxidation resistance. We show that the amorphous-to-crystal transition driven by epitaxy is the process behind the growth of rubrene films with single-crystal-like properties. Growth optimisation expedites this transition and greatly improves the homogeneity of the films.

The surface transformation and defect evolution of Cu-doped SrTiO3 upon copper exsolution have been studied by exploiting a multi-technique approach which integrates, for the first time, common methods describing exsolution like XAS, XPS and STEM with unconventional strategies, namely electron paramagnetic resonance (EPR) and UV-Vis diffuse reflectance (UV-DRS). XAS and EPR indicated that copper is present in the matrix in a disordered coordination environment as amorphous Cu2O and CuO located at the surface and as substitutional Cu2+ lattice species with a distorted octahedral structure. Interestingly, EPR unveiled that, during exsolution, Cu2+ surface sites with disordered coordination primarily migrate undergoing selective reduction, while a delay is observed for the lattice defects. UV-DRS resulted in a valid alternative to HRTEM to determine the size of exsolved nanoparticles by tracking the plasmon resonance effect. Moreover, when XANES showed the complete regain of the pristine state of Cu after reoxidation, both UV-DRS and EPR highlighted that the original features are not entirely restored. These outcomes suggest that the chemical environment of exsolvable species is much more heterogeneous and the exsolution process much less straightforward than expected. Thus, alternative and original characterization techniques should be exploited to provide a solid methodological benchmark for an effective evaluation of this phenomenon.

Crystallinity is a key parameter for technological and medical applications of poly(lactic acid) (PLA) microspheres. This study explores a novel emulsification-based method for regulating the crystalline structure of PLA microspheres. The results unveil the effects of changing the emulsification temperature in an unexplored temperature range above the boiling point of the solvent used to dissolve the polymer. Powder X-ray diffraction, differential scanning calorimetry, and micro-Raman analysis show that poly(L-lactic acid) (PLLA) microsphere batches display a crystalline fraction, which can be varied by a factor 2, from 19 to 38%. Notably, the comparison between macro- and microanalysis supports a model in which the emulsification temperature influences the ratio between amorphous and crystalline parts within each PLLA microsphere. The microspheres do not show any infrared-active changes in the molecular unit after exposure to X-rays, unlike the bulk material. The findings pave the way for innovative strategies for obtaining radiation-resistant microspheres with controlled crystallinity.

Optical control is achieved on the excited state energy transfer between spatially separated donor and acceptor molecules, both coupled to the same optical mode of a cavity. The energy transfer occurs through the formed hybrid polaritons and can be switched on and off by means of ultraviolet and visible light. The control mechanism relies on a photochromic component used as donor, whose absorption and emission properties can be varied reversibly through light irradiation, whereas in-cavity hybridization with acceptors through polariton states enables a 6-fold enhancement of acceptor/donor contribution to the emission intensity with respect to a reference multilayer. These results pave the way for synthesizing effective gating systems for the transport of energy by light, relevant for light-harvesting and light-emitting devices, and for photovoltaic cells.

The ability to control the properties of organic thin films is crucial for obtaining highly performant thin-film devices. However, thin films may experience post-growth processes, even when the most sophisticated and controlled growth techniques such as organic molecular beam epitaxy (OMBE) are used. Such processes can modify the film structure and morphology and, thus, the film properties ultimately affecting device performances. For this reason, probing the occurrence of post-growth evolution is essential. Equally importantly, the processes responsible for this evolution should be addressed in view of finding a strategy to control and, possibly, leverage them for driving film properties. Here, nickel-tetraphenylporphyrin (NiTPP) thin films grown by OMBE on highly oriented pyrolytic graphite (HOPG) are selected as an exemplary system exhibiting a remarkable post-growth morphology evolution consistent with Ostwald-like ripening. To quantitatively describe the growth, the height–height correlation function (HHCF) analysis of the atomic force microscopy (AFM) images is carried out, clarifying the role of the post-growth evolution as an integral part of the whole growth process. The set of scaling exponents obtained confirms that the growth is mainly driven by diffusion combined with the presence of step-edge barriers, in agreement with the observed ripening phenomenon. Finally, the results together with the overall approach adopted demonstrate the reliability of the HHCF analysis in systems displaying post-growth evolution.

Exposure of polymers to ionizing radiation and high-energy particle beams is involved in many processes - from food sterilization to radiotherapy protocols. The resulting effects, at the final stages, determine the functional, structural, and morphological alteration of the material. However, the processes responsible for cumulative chain scission, crosslinking, and reactions with the environment are often difficult to disentangle as a sequence of elementary events. Here we report a spectroscopic study - by attenuated-total reflection Fourier transform infrared spectroscopy and powder x-ray diffraction measurements, together with differential scanning calorimetry and thermogravimetric analyses - that sheds light on the very initial stages of the mechanisms involved in radiation-induced modifications of poly(lactic acid) (PLA). The results, collected on samples from biobased processes and exposed to low x-ray doses in the range of 10(0)-10(3)Gy after different thermal treatments, show spectroscopic evidence of the emergence of molecular unit perturbations - mainly related to methyl and carbonyl groups with the formation of C=C double bonds - with a clear-cut dependence on the polymer conformation. Understanding the mechanisms involved and the role of crystallinity provides information potentially useful for the development of PLA with a suitable radiation hardness for applications in radiotherapy.

One of the keys for the development of porphyrin-based devices implies that their functionality must be robust and stable against external environmental factors. While the research has been mostly focused on the supramolecular aggregate interactions with target chemicals, the robustness of organic nanostructures in contaminating and even aggressive environments has not been diffusely investigated yet. The results here presented show that crystalline nanowires of meso -tetraphenyl porphyrin (H 2 TPP) and meso -tetraphenyl porphyrin-Zn(II) (ZnTPP) are insensitive to the exposure to a series of purposely chosen analytes (alcohols, alkanes and amines). Our finding suggests possible applications of the nanowires in organic-based devices (overwhelming the well-known intrinsic weakness of organic electronics), related to material stability through an appropriate material design and the opportunity offered by organic epitaxy.

Upon aging and exposure to ambient conditions, acrylic colors get dry and the degree of polymerization of the polymer matrix increases due to progressive cross-linking. When interested in studying acrylic colors, separation of the different components, namely matrix, pigments, and fillers, may be particularly useful for their identification and characterization. In the case of aged acrylic colors, as found in artworks themselves or in materials present in artist studios, the separation approaches requiring chemical treatments of fluid samples cannot be applied. To overcome this limit, here a controlled combustion strategy is developed for eliminating the polymer matrix from the color and then recovering a powder made of pigments and fillers, which is analyzed by optical spectroscopy and demonstrated to display the same chromatic/chemical properties of the original color. As a case study, the new method is successfully applied to acrylic colors used by the Italian artist Domenico “Ico” Parisi (1916–1996), found in the original tubes in his studio.

Acrylic colors are mixtures of several components that can be identified as pigments, binders, and fillers, so that, when analyzed, the characteristic response of the different components may not be recognizable. This limits the accuracy of spectroscopic techniques, nonetheless particularly useful as they are noninvasive and can be applied in situ on real artworks. Here, a method is proposed to chemically separate and identify the different components of acrylic colors, in order to be able to study their spectroscopic response separately, in particular by ultraviolet–visible–near-infrared diffuse reflectance. The results clearly show that the chemical and analytical method developed here is fully reliable, with the advantage of clearly separating the response of the different components without any change of their chromatic/chemical properties. As a case study, the new method is applied here to original acrylic colors used by the Italian artist Ico Parisi, in view of building a spectra database.

The nature of optical excitations and the spatial extent of excitons in organic semiconductors, both of which determine exciton diffusion and carrier mobilities, are key factors for the proper understanding and tuning of material performances. Using a combined experimental and theoretical approach, we investigate the excitonic properties of meso-tetraphenyl porphyrin-Zn(II) crystals. We find that several bands contribute to the optical absorption spectra, beyond the four main ones considered here as the analogue to the four frontier molecular orbitals of the Gouterman model commonly adopted for the isolated molecule. By using many-body perturbation theory in the GW and Bethe–Salpeter equation approach, we interpret the experimental large optical anisotropy as being due to the interplay between long- and short-range intermolecular interactions. In addition, both localized and delocalized excitons in the π-stacking direction are demonstrated to determine the optical response, in agreement with recent experimental observations reported for organic crystals with similar molecular packing.

Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel’s effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material.