BINA

Direct detection of intrinsic defects in halide perovskites (HaPs) by standard methods utilizing optical excitation is quite challenging, due to the low density of defects in most samples of this family of materials (≤ 1015 cm− 3 in polycrystalline thin films and≤ 1011 cm− 3 in single crystals, except melt-grown ones). While several electrical methods can detect defect densities< 1015 cm− 3, such as deep level transient spectroscopy (DLTS) or thermally stimulated current (TSC), they require preparation of ohmic and/or rectifying electrical contacts to the sample, which not only poses a challenge by itself in the case of HaPs but also may create defects at the contact− HaP interface and introduce extrinsic defects into the HaP. Here, we show that low-energy photoelectron spectroscopy measurements can be used to obtain directly the energy position of gap states in Br-based wide-bandgap (Eg> 2 eV) HaPs. By measuring HaP layers on both hole-and electron-contact layers, as well as single crystals without contacts, we conclude that the observed deep defects are intrinsic to the Br-based HaP, and we propose a passivation route via the incorporation of a 2D-forming ligand into the precursor solution.

The papers in this volume were part of the technical conference cited on the cover and title page. Papers were selected and subject to review by the editors and conference program committee. Some conference presentations may not be available for publication. Additional papers and presentation recordings may be available online in the SPIE Digital Library at SPIEDigitalLibrary. org.

Ion migration and subsequent accumulation at interfaces, driven by the built-in potential (Vbi), are intrinsic properties of halide perovskite solar cells (PVSCs), which mostly decrease device performance. To address this issue, we constructed favorable ion accumulation in perovskite solar cell by illumination to improve quasi-2D PVSCs performance. This design dramatically improves the photo-carrier collection and enables significant device performance improvement from 14.6% to 19.05%, one of the best results for quasi-2D PVSCs. We argue that the light-triggered favorable ion accumulation originates from 1) photo-induced quasi-fermi level splitting that compensates the Vbi, so as to avoid the ion accumulation that decreases Vbi, and 2) the light intensity distribution-induced uneven ion potential further drives the segregation of mobile ions towards favorable ion accumulation, decreasing any I- gradient between …

A way of modulating the solid-state electron transport (ETp) properties of oligopeptide junctions is presented by charges and internal hydrogen bonding, which affect this process markedly. The ETp properties of a series of tyrosine (Tyr)-containing hexa-alanine peptides, self-assembled in monolayers and sandwiched between gold electrodes, are investigated in response to their protonation state. Inserting a Tyr residue into these peptides enhances the ETp carried via their junctions. Deprotonation of the Tyr-containing peptides causes a further increase of ETp efficiency that depends on this residue’s position. Combined results of molecular dynamics simulations and spectroscopic experiments suggest that the increased conductance upon deprotonation is mainly a result of enhanced coupling between the charged C-terminus carboxylate group and the adjacent Au electrode. Moreover, intra-peptide hydrogen …

Combinatorial material science crucially depends on robust, high-throughput characterization methods. While X-ray photoelectron spectroscopy (XPS) may provide detailed information about chemical and electronic properties, it is a time-consuming technique and, therefore, is not viewed as a high-throughput method. Here we present preliminary XPS data of 169 measurement spots on a combinatorial 72 × 72 cm² CuₓNi₁₋ₓOy compositional library to explore how characterization and evaluation routines can be optimized to improve throughput in XPS for combinatorial studies. In particular, two quantification approaches are compared. We find that a simple integration (of XPS peak regions) approach is suited for fast evaluation of, in the example system, the [Cu]/([Cu] + [Ni]) ratio. Complementary to that, the time-consuming (XPS peak-) fit approach provides additional insights into chemical speciation and oxidation state changes, without a large deviation of the [Cu]/([Cu] + [Ni]) ratio. This insight suggests exploiting the fast integration approach for ‘real time’ analysis during XPS data collection, paving the way for an ‘on-the-fly’ selection of points of interest (i.e., areas on the sample where sudden composition changes have been identified) for detailed XPS characterization. Together with the envisioned improvements when going from laboratory to synchrotron-based excitation sources, this will shorten the analysis time sufficiently for XPS to become a realistic characterization option for combinatorial material science.

This chapter describes the experimental setups and measurement protocols used in the characterization of forward Brillouin scattering processes in optical fibers. The methods can be broadly classified in three categories: techniques in which forward Brillouin scattering is accumulated and integrated over the entire length of a fiber under test, point measurements at specific locations, and spatially distributed analysis of the scattering spectra as functions of position. Specific examples include the spontaneous scattering of probe waves within fiber interferometer loops, polarization rotation of probe waves, photoelastic perturbations of fiber Bragg gratings, coupling of power between forward Brillouin pump tones, and spatially distributed mapping of auxiliary backscattering processes such as Rayleigh or backward Brillouin. Lastly, the spatially distributed analysis of inter-modal scattering over polarization-maintaining …

Lignin derived bimetallic platinum group metal-free electrocatalysts for the oxygen reduction reaction in acid and alkaline media IRIS IRIS Home Sfoglia Macrotipologie & tipologie Dipartimento Autore Titolo Tipologia Settore Scientifico Disciplinare IT Italiano Italiano English English LOGIN 1.IRIS 2.Pubblicazioni 3.02 - Intervento a convegno Muhyuddin, M., Poli, F., Petri, E., Basile, F., Fasolini, A., Elbaz, L., et al. (2022). Lignin derived bimetallic platinum group metal-free electrocatalysts for the oxygen reduction reaction in acid and alkaline media. Intervento presentato a: 73rd Annual Meeting of the International Society of Electrochemistry - 23 - 28 October 2022 Xiamen, Fujian, China, Virtual, online. Lignin derived bimetallic platinum group metal-free electrocatalysts for the oxygen reduction reaction in acid and alkaline media M. Muhyuddin; C. Santoro 2022 Scheda breve Scheda completa Scheda completa (DC) SFX …

Aerogels are a very interesting group of materials owing to their unique physical and chemical properties. In the context of electrocatalysis, the focus has been on their physical properties, and they have been used primarily catalyst supports so far. In this work, we synthesized porphyrin aerogels containing Ni and NiFe mixed metal materials and studied them as catalysts for the oxygen evolution reaction (OER). Different Ni:Fe ratios were synthesized and studied in electrochemical cells, and DFT calculations were conducted in order to gain insight into their behavior. The activity trends were dependent on the metal ratios and differ from known NiFeOOH materials due to the change of the oxidation states of the metals to higher numbers. Herein, we show that Ni and Fe have a synergistic effect for OER, despite being structurally separated. They are connected electronically, though, through a large organic aromatic …

Atomic and molecular layer deposition (ALD and MLD) are techniques based on surface‐directed self‐limiting reactions that afford deposition of films controlled at the monolayer level and with extreme conformality, even on ultra‐high‐aspect‐ratio and porous substrates. These methodologies are typically used to deposit thin films with desirable physical properties and functionality. Here, the MLD process is harnessed to demonstrate the growth of molecularly thin chiral films that inherit a desirable chemical property directly from the source precursor: using this innovative technique, enantioselective nanosurfaces are managed to be grown. Specifically, the formation of a Zn/Cysteine nanostructure by MLD is demonstrated for both the l‐ and d‐ enantiomers. The reaction and growth mechanism of these chiral hybrid inorganic‐organic nanosurfaces are studied via various experimental procedures; their …

Color induction in nitrogen-contaminated diamonds was carried out via various procedures that involve irradiation, thermal treatments (annealing), and more. These treatments affect vacancy defect production and atom orientation centers in the diamond lattice. Natural diamonds underwent color enhancement treatments in order to produce green, blue, and yellow fancy diamonds. The aim of this study was to follow the changes occurring during the treatment, mainly by EPR spectroscopy, which is the main source for the determination of the effect of paramagnetic centers (carbon-centered radicals) on the color centers produced via the treatments, but also via visual assessment, fluorescence, UV-vis, and FTIR spectroscopy. The results indicate that diamonds containing high levels of nitrogen contamination are associated with high carbon-centered radical concentrations. Four paramagnetic center structures (N1, N4, and P2/W21) were generated by the treatment. It is suggested that the N4 structure correlates with the formation of blue color centers, whereas yellow color centers are attributed to the presence of N1 species. While to produce blue and yellow colors, a thermal treatment is needed after irradiation, for treated green diamonds, no thermal treatment is needed (only irradiation).

Proteinoid nanoparticles composed of l‐lysine and l‐phenylalanine were prepared and showed enantioselective adsorption of l‐amino acids at various pH values, emphasizing the chiral nature of the particles. The adsorption was examined using circular dichroism, isothermal titration calorimetry and ζ‐potential measurements. Positively charged ammonium moieties on the proteinoid surface are most likely responsible for the enantioselective adsorption owing to their chirality which originates from l‐lysine. Accordingly, a higher enantiomeric excess was found for amino acids such as alanine with a more negative charge.

Controlling nerve cells to form pre‐designed 3D neural networks that recapitulate the intricate neural interconnectivity in the brain is essential for developing neuronal interfaces and new regeneration approaches. Here, nerve cells within 3D biomaterials are dynamically localized using nano‐based magnetic manipulations. Nerve cells are transformed into magnetic units and their organizational layout is manipulated using external magnetic field gradients. Iron oxide nanoparticles are incorporated into both Pheochromocytoma cell‐line 12 (PC12) cells and primary mice cortical neurons and the magnetized cells are subjected to multiple magnetic fields using pre‐designed magnetic arrays. Their movement is controlled inside multi‐layered 3D collagen scaffolds, which simulate the innate properties of in‐vivo tissue structures. Via these magnetic manipulations, functional 3D microarchitectures of neural networks are …

Recent research points to mesenchymal stem cells’ potential for treating neurological disorders, especially drug addiction. We examined the longitudinal effect of placenta-derived mesenchymal stromal-like cells (PLX-PAD) in a rat model for cocaine addiction. Sprague–Dawley male rats were trained to self-administer cocaine or saline daily until stable maintenance. Before the extinction phase, PLX-PAD cells were administered by intracerebroventricular or intranasal routes. Neurogenesis was evaluated, as was behavioral monitoring for craving. We labeled the PLX-PAD cells with gold nanoparticles and followed their longitudinal migration in the brain parallel to their infiltration of essential peripheral organs both by micro-CT and by inductively coupled plasmaoptical emission spectrometry. Cell locations in the brain were confirmed by immunohistochemistry. We found that PLX-PAD cells attenuated cocaine-seeking behavior through their capacity to migrate to specific mesolimbic regions, homed on the parenchyma in the dentate gyrus of the hippocampus, and restored neurogenesis. We believe that intranasal cell therapy is a safe and effective approach to treating addiction and may offer a novel and efficient approach to rehabilitation.

Atomic and molecular layer deposition (ALD and MLD) are techniques based on surface‐directed self‐limiting reactions that afford deposition of films controlled at the monolayer level and with extreme conformality, even on ultra‐high‐aspect‐ratio and porous substrates. These methodologies are typically used to deposit thin films with desirable physical properties and functionality. Here, the MLD process is harnessed to demonstrate the growth of molecularly thin chiral films that inherit a desirable chemical property directly from the source precursor: using this innovative technique, enantioselective nanosurfaces are managed to be grown. Specifically, the formation of a Zn/Cysteine nanostructure by MLD is demonstrated for both the l‐ and d‐ enantiomers. The reaction and growth mechanism of these chiral hybrid inorganic‐organic nanosurfaces are studied via various experimental procedures; their …

Chiral surfaces, developed in the last decade, serve as media for enantioselective chemical reactions. Until today, they have been based mostly on developments in silica templating, and are made mainly from imprints of silicate materials developed a long time ago. Here, a chiral porous activated carbon surface was developed based on a chiral ionic liquid, and the surface chemistry and pore structure were studied to lay a new course of action in the field. The enantioselectivities of surfaces are examined by using variety of methods such as circular dichroism, linear sweep voltammetry and catalysis. These techniques revealed a 28.1% preference for the D enantiomer of the amino acid proline, and linear sweep voltammetry confirmed chirality recognition by another probe. An aldol surface chiral catalytic reaction was devised and allowed to determine the root of the enantiomeric excess. These results affirm the path …

In a wide spectrum of neurodegenerative diseases, self-assembly of pathogenic proteins to cytotoxic intermediates is accelerated by the presence of metal ions such as Cu2+. Only low concentrations of these early transient oligomeric inter-mediates are present in a mixture of species during fibril formation, and hence information on the extent of structuring of these oligomers is still largely unknown. Here, we investigate dimers as the first intermediates in the Cu2+-driven aggrega-tion of a cyclic D,L-α-peptide architecture. The unique structural and functional properties of this model system recapitu-late the self-assembling properties of amyloidogenic proteins including β-sheet conformation and cross-interaction with pathogenic amyloids. We show that a histidine-rich cyclic D,L-α-octapeptide binds Cu2+ with high affinity and selectivity to generate amyloid-like cross-β-sheet structures. By taking advantage of …

Practical implementation of anion exchange membrane fuel cells mainly relies on the choice of highly active and stable oxygen reduction reaction (ORR) catalysts. Transition metal oxides based on Group 4 and 5 are well known for their chemical stability and corrosion‐resistance and they are earth‐abundant too. Among them, zirconia (ZrO2) has exceptional chemical stability, but its poor conductivity and less active sites hinder the application of zirconia‐based materials toward ORR. In order to bring out the best activity from ZrO2, careful site engineering without losing the phase purity and chemical stability is essential. In this context, nitrogen doping on tetragonal zirconia (t‐ZrO2) as a viable method to obtain a highly active ORR catalyst is adopted. The temperature for the phase pure synthesis of t‐ZrO2 is optimized by crystallographic study. The nitrogen doping in the zirconia lattice is confirmed by various …

Methods: Using high-throughput RNA sequencing data from human islets and EndoC-βH1 cells exposed to IFNα or IFNγ/IL1β, we evaluated the role of ADAR1 in human pancreatic β cells and determined the impact of the type 1 diabetes pathophysiological environment on ADAR1-dependent RNA editing.Results: We show that both IFNα and IFNγ/IL1β stimulation promote ADAR1 expression and increase the A-to-I RNA editing of Alu-Containing mRNAs in EndoC-βH1 cells as well as in primary human islets.Discussion: We demonstrate that ADAR1 overexpression inhibits type I interferon response signaling, while ADAR1 silencing potentiates IFNα effects. In addition, ADAR1 overexpression triggers the generation of alternatively spliced mRNAs, highlighting a novel role for ADAR1 as a regulator of the β cell transcriptome under inflammatory conditions.

Herein, centrosymmetric aluminum plasmonic structures composed of triangular cavities are studied and their long‐range coupling by cathodoluminescence nanoscopy are visualized. Four different plasmonic structures containing the same subunit are studied. The plasmonic modes of the individual triangular subunits are localized at the triangle sides rather than at the vertices, in agreement with other studies. Yet, upon strong interaction between the cavities, a redistribution of the electromagnetic field is observed such that it delocalizes around the cavities in the form of a contour, providing a mode enhancement and a pronounced nonlinear response as observed by second harmonic generation. Comparison between plasmonic structures made of either silver or aluminum reveals that the metal dielectric function plays an important role in the interaction between the cavities. This work provides a rationale for …