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The parent compound of high-Tc superconducting cuprates is a unique Mott insulator consisting of layers of spin-1/2 ions forming a square lattice and with a record high in-plane antiferromagnetic coupling. Compounds with similar characteristics have long been searched for without success. Here, we use a combination of experimental and theoretical tools to show that commercial AgF₂ is an excellent cuprate analog with remarkably similar electronic parameters to La₂CuO₄ but larger buckling of planes. Two-magnon Raman scattering and inelastic neutron scattering reveal a superexchange constant reaching 70% of that of a typical cuprate. We argue that structures that reduce or eliminate the buckling of the AgF₂ planes could have an antiferromagnetic coupling that matches or surpasses the cuprates.

Real-time stimulation and recording of neural cell bioelectrical activity could provide an unprecedented insight in understanding the functions of the nervous system, and it is crucial for developing advanced in vitro drug screening approaches. Among organic materials, suitable candidates for cell interfacing can be found that combine long-term biocompatibility and mechanical flexibility. Here, we report on transparent organic cell stimulating and sensing transistors (O-CSTs), which provide bidirectional stimulation and recording of primary neurons. We demonstrate that the device enables depolarization and hyperpolarization of the primary neuron membrane potential. The transparency of the device also allows the optical imaging of the modulation of the neuron bioelectrical activity. The maximal amplitude-to-noise ratio of the extracellular recording achieved by the O-CST device exceeds that of a microelectrode array system on the same neuronal preparation by a factor of 16. Our organic cell stimulating and sensing device paves the way to a new generation of devices for stimulation, manipulation and recording of cell bioelectrical activity in vitro and in vivo . A transparent organic field-effect transistor allows the stimulation and recording of the bioelectrical activity of primary neural cells. The cells grow, differentiate and function on the device, which then provides the electrical stimulation, and enables the recording of extracellular current and optical imaging of the modulation of neuronal membrane potential.

The quality and the performance of hybrid perovskite (HP)’s films strongly depend on the complete conversion into MAPbI3 of a spin-coated solution of methylammonium iodide (MAI) and PbI2. Highly crystalline PbI2 on a substrate limits such a conversion and, consequently, the HP’s solar cell performances. We investigate for the first time the use of short-chain organic acids as additives in a non-complexing solvent like γ-butyrolactone (GBL), that can retard retard the crystallization of PbI2. Based on XRD analyses of the spin coated films, the acetic acid is the most effective additive in retarding the PbI2 crystallization, making Pb2+ available for a subsequent reaction with MAI. These results open a new experimental path for fabricating perovskite films by single or sequential step methods involving acid additives.

Due to their exceptional properties, the study of hybrid perovskite (HyP) structures and applications dominate current photovoltaic prospects. Methylammonium lead tri-iodide perovskite (MAPI) is the model compound of the HyP class of materials that, in a few years, achieved, in photovoltaics, a power conversion efficiency of 25%. The attention on HyP has recently moved to large single crystals as emerging candidates for photovoltaic application because of their improved stability and optoelectronic properties compared to polycrystalline films. To control the quality and symmetry of the large MAPI single crystals, we proposed an original method that consisted of adding short-chain carboxylic acids to the inverse temperature crystallization (ICT) of MAPI in γ-butyrolactone (GBL). The crystals were characterized by single-crystal X-ray diffraction (SC-XRD), X-ray powder diffraction (XRPD) and Raman spectroscopy. Based on SC-XRD analysis, MAPI crystals grown using acetic and trifluoroacetic acids adopt a tetragonal symmetry “I4cm”. MAPI grown in the presence of formic acid turned out to crystallize in the orthorhombic “Fmmm” space group demonstrating the acid’s effect on the crystallization of MAPI.

Solution‐processed organic and hybrid semiconductor materials have great potential for ionizing radiation direct detection, as they combine high sensitivity, low‐power consumption, and flexibility. There is, however, an open challenge related to the stability in ambient/operational conditions of this class of devices. In this work, an air‐stable, solution‐processed and flexible X‐ray detector is reported, based on the integration of hybrid perovskite and organic thin films used as active layer and functional interlayers, respectively. The diode architecture and the engineering of the interface between the hybrid perovskite and the organic hole transporting material (solvent‐modified poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate) is the key to achieve enhanced detector's air stability and performance. The unencapsulated flexible device, measured in air and in passive operation (0 V), shows a limit‐of‐detection of 0.37 ± 0.04 µGy s−1 and a sensitivity as high as 5.2 µC Gy−1 cm−2, which is retained within 25% after 42 days exposure to ambient conditions. An air‐stable, solution‐processed, and flexible X‐ray detector, based on hybrid perovskite and organic thin films incorporated in photodiode architecture, is reported. The unencapsulated flexible device, working in passive operation (0 V) and in ambient conditions, shows sensitivity as high as 5.2 µC Gy−1 cm−2 which is retained within 25% after 42 days in air.

Indium sulphide has been extensively investigated as a component for different kind of photovoltaic devices (organic-inorganic hybrid devices, all inorganic, dye sensitized cells). In this paper, we have optimised the growth conditions of indium sulphide thin films by means of a low cost, versatile deposition technique, like spray pyrolysis. The quality of the deposited films has been characterised by micro-Raman, vis-UV spectroscopy, and atomic force microscopy. Substrate deposition temperature and different postdeposition annealing conditions have been investigated in order to obtain information about the quality of the obtained compound (which crystalline or amorphous phases are present) and the morphology of the deposited films. We have shown that the deposition temperature influences strongly the amount of amorphous phase and the roughness of the indium sulphide films. Optimised postdeposition annealing treatments can strongly improve the final amount of the beta phase almost independently from the percentage of the amorphous phase present in the as deposited films.

The basic concept for efficiency improvement in dye-sensitized solar cells (DSSC) is limiting the electron-hole recombination. One way to approach the problem is to improve the photogenerated charge carriers lifetime and consequently reduce their recombination probability. We are reporting on a facile posttreatment of the mesoporous photoanode by using a colloidal solution of TiO2 nanoparticles. We have investigated the outcome of the different sintering temperature of the posttreated photoanodes on their morphology as well as on the conversion efficiency of the DSSC. The DSSCs composed of posttreated photoanodes at 450°C showed an increase in J SC and consequently an increase in efficiency of 10%. Investigations were made to determine the electron recombination via the electrolyte by the OCVD technique. We found that the posttreatment has the effect of reducing the surface trap states and thus increases the electron lifetime, which is responsible for the increase of the overall cell efficiency.

Among solution-processable metal oxides, zinc oxide (ZnO) nanoparticle inks are widely used in inverted organic solar cells for the preparation, at relatively low temperatures (<120 °C), of highly efficient electron-transporting layers. There is, however, a recent interest to develop more sustainable and less impacting methods/strategies for the preparation of ZnO NPs with controlled properties and improved performance. To this end, we report here the synthesis and characterization of ZnO NPs obtained using alternative reaction solvents derived from renewable or recycled sources. In detail, we use (i) recycled methanol (r-MeOH) to close the loop and minimize wastes or (ii) bioethanol (b-EtOH) to prove the effectiveness of a bio-based solvent. The effect of r-MeOH and b-EtOH on the optical, morphological, and electronic properties of the resulting ZnO NPs, both in solution and thin-films, is investigated, discussed, and compared to an analogous reference material. Moreover, to validate the properties of the resulting materials, we have prepared PTB7:PC71BM-based solar cells containing the different ZnO NPs as a cathode interlayer. Power conversion efficiencies comparable to the reference system (≈7%) were obtained, validating the proposed alternative and more sustainable approach.

Skin disorders are widespread around the world, affecting people of all ages, and oxidative stress represents one of the main causes of alteration in the normal physiological parameters of skin cells. In this work, we combined a natural protein, fibroin, with antioxidant compounds extracted in water from pomegranate waste. We demonstrate the effective and facile fabrication of bioactive and eco-sustainable films of potential interest for skin repair. The blended films are visually transparent (around 90%); flexible; stable in physiological conditions and in the presence of trypsin for 12 days; able to release the bioactive compounds in a controlled manner; based on Fickian diffusion; and biocompatible towards the main skin cells, keratinocytes and fibroblasts. Furthermore, reactive oxygen species (ROS) production tests demonstrated the high capacity of our films to reduce the oxidative stress induced in cells, which is responsible for various skin diseases.

The quality and the performance of hybrid perovskite (HP)’s films strongly depend on the complete conversion into MAPbI[sub.3] of a spin-coated solution of methylammonium iodide (MAI) and PbI[sub.2] . Highly crystalline PbI[sub.2] on a substrate limits such a conversion and, consequently, the HP’s solar cell performances. We investigate for the first time the use of short-chain organic acids as additives in a non-complexing solvent like γ-butyrolactone (GBL), that can retard retard the crystallization of PbI[sub.2] . Based on XRD analyses of the spin coated films, the acetic acid is the most effective additive in retarding the PbI[sub.2] crystallization, making Pb[sup.2+] available for a subsequent reaction with MAI. These results open a new experimental path for fabricating perovskite films by single or sequential step methods involving acid additives.