In this paper, wide-gap Cu (In,Ga)(S,Se)2 thin-film solar cells are studied in view of their performance, limitations, and opportunities for further optimization. To this end, a wide variety of properties is investigated. This includes the role of gallium gradients, grain size effects, electronic properties, doping metastabilities, and minority carrier lifetime. Particular emphasis is placed on the impact of alkali atoms. A comparison of surface, interface, and grain boundary chemistry shows systematic atomic accumulation and depletion effects. This leads to electronic modifications in the grain boundary regions of the absorber. Heavy alkali treatments also influence the device properties, giving a clear boost of open-circuit voltage. By the combination of different experimental results, this positive open-circuit voltage effect has been explained in terms of reduction of interface recombination. The latter effects are discussed in view of a possible alkali-indium-selenium bond formation at the interface between the absorber and the buffer layer. The properties of a 14.2%-efficient Cu (In,Ga)Se2-based device with [Ga]/([Ga] + [In]) = 0.8 and a wide optical band gap of 1.48 eV are investigated, also in view of further opportunities for improvement.

It has been argued that the Li7La3Zr2O12/Li hetero-interface in all-solid-state batteries is prone to decomposition and degradation during synthesis and cycling, leading to the formation of Li dendrites and their propagation inside the Li7La3Zr2O12 bulk. However, the exact formation mechanism of these dendrites, as well as their chemical composition, remains not fully understood until now due to the difficulty of quantifying the Li concentration within the battery materials. Therefore, in this work, we employed atom probe tomography in conjunction with advanced transmission electron microscopy to investigate the Li7La3Zr2O12 bulk in the vicinity of the Li7La3Zr2O12/Li heterointerface, a region prone to crack formation and propagation. We discovered that numerous Li-nanodendrites are present inside the LLZO bulk close to the Li/LLZO interface and that these nanodendrites appear similar to cracks being filled by Li. Therefore, this study raises a possible dilemma of causality between the crack formation and Li segregation in LLZO grains. Interestingly, advanced microscopy investigations prove the existence of a high density of dislocations within LLZO for some grains. Moreover, the finite element modeling suggests that the dislocations' cores can act as nucleation sites for strong Li segregation, leading to an increase in hydrostatic stress. This implies that this strong Li segregation at the dislocation cores and the resultant high hydrostatic stress might be the cause for the crack formation. Subsequently, Li can be further accumulated at the cracks, forming the Li-nanodendrites. It is without doubt that the presence of such microscopic Li-rich nanodendrites in the as-deposited state will lead to the growth and propagation of the well-known macroscopic Li dendrites during cycling.

Aluminum nitride III‐V semiconductor nanoparticles are prepared in the liquid phase via a two‐step synthesis. In a first step, a mixed amide‐imide intermediate is prepared in liquid ammonia. In a second step, the ammonolysis is completed by microwave heating at 300 °C in [BMIm][NTf 2 ] as an ionic liquid to obtain crystalline β‐AlN, which is usually known as a high‐pressure phase. The nanoparticles have a size of 3.7 ± 0.7 nm. Particle size and chemical composition are examined by transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, infrared spectroscopy, and X‐ray powder diffraction. According to UV–vis spectroscopy and a Tauc plot, a bandgap of 5.2 eV is determined. The AlN nanoparticles show photoluminescence with bluish white emission and a quantum yield of 15%, which is a typical value for core‐type semiconductor nanoparticles without a protecting shell. A liquid‐phase synthesis of crystalline AlN nanoparticles (<10 nm) showing visible emission at room temperature is reported for the first time.

Aluminum nanoparticles, Al(0), are prepared in toluene at room temperature (25 degrees C) by reduction of AlH3 with dilithium naphthalenide ([Li(2)Naph]). To dissolve the starting materials in toluene, AlH3 and [Li(2)Naph] are coordinated by N,N,N ',N '-tetramethylethylendiamin (TMEDA). The as-prepared Al(0) nanoparticles are monocrystalline and exhibit a uniform size of 11 +/- 3 nm with narrow size distribution. They are highly reactive, as indicated by reaction in air and even with nitrogen. Besides the formation of Al(0) nanoparticles, the [Li(2)Naph]-driven reduction of AlH3 results in the formation of LiAlH4 as a side phase, which can be removed but is difficult to remove due to its low solubility in solvents that do not react with the Al(0) nanoparticles (e.g., toluene, THF). The presence of LiAlH4 and the formation of a Al(0) nanoparticle/LiAlH4 composite, however, turned out to be advantageous in regard to H-2 sorption. After thermal transition of LiAlH4 to LiH (250 degrees C, vacuum), the resulting Al(0) nanoparticle/LiH composite shows promising H-2 sorption and H-2 uptake at 250 degrees C and 100 bar of H-2 with a gravimetric capacity of 3.8%. After modification of the Al(0) nanoparticles with 1 wt % Pd for activation, the H-2 uptake occurs at even a reduced temperature of 150 degrees C.

We investigate magnetron-sputtered In2(OxS1−x)3 compounds acting as an alternative buffer system to the solution-grown CdS or Zn(O,S) buffer layers in Cu(In,Ga)Se2 (CIGS) thin-film solar cells. The influence of the oxygen content on the solar cell performance, microstructure of the mixed systems, bandgap, and band offsets to CIGS is investigated experimentally and also characterized by calculations based on density functional theory. Samples in a series with different chemical compositions ranging from In2S3 to In2O3 are either directly deposited from ceramic targets or from a pure In2S3 target by reactive sputtering by adding O2 in the Ar sputtering gas. The binary compounds In2S3 and In2O3 sputtered at 220 °C substrate temperature from ceramic targets exhibit a crystalline structure, whereas the ternary In2(O,S)3 compounds are either nanocrystalline in the case of In2(O0.25S0.75)3 or amorphous for In2(O0.5S0.5)3 and In2(O0.75S0.25)3. For [O]/([O] + [S]) ratios above 0.25, the cell efficiencies decrease drastically, mainly due to lower open-circuit voltages (VOC). This behavior can be explained by an increase of the negative conduction band offset between the CIGS absorber and the oxygen-rich In2(OxS1−x)3 or In2O3 buffer, resulting in pronounced VOC losses. Adding oxygen to In2S3 with optical bandgap energies of around 2 eV results in a bowing of the values to below 2 eV and finally reaching values of around 2.7 eV for In2O3 if an indirect band transition is assumed. In summary, our results reveal that pronounced oxygen incorporation in In2S3 is not beneficial in terms of CIGS device efficiency because oxygen is electronically inactive and poorly miscible.

A time-dependent reaction-diffusion model was elaborated to better understand the dynamical growth of contamination on surfaces illuminated by an electron beam. The goal of this work was to fully describe the flow of hydrocarbon molecules, denoted as contaminants, and their polymerization in the irradiated area with the number of parameters reduced to a minimum necessary. It was considered that the diffusion process of contaminants is driven by the gradient of their surface density generated by the impact of a circular homogeneous electron beam. The contribution of the residual gas atmosphere in the instrument was described by the tendency to reestablish the initial equilibrium surface density of contaminants before irradiation. The four unknown parameters of the model, the electron interaction cross-section, the diffusion coefficient, the initial surface density of contaminants, and the frequency of the supply of contaminants from the residual gas atmosphere were determined by comparing the modeled contamination growth with experimental results. The experiments were designed such that the influence of the single parameters could be unequivocally separated. To follow the dynamical evolution of the system and to generate time-resolved distinct experimental data, successive contamination measurements were performed at short time intervals up to 20 min. The local height and shape of the grown contamination were quantified by evaluating high-angle annular dark-field (HAADF) scanningtransmission- electron-microcopy (STEM) image intensities and corresponding Monte-Carlo simulations. Our model also applies to nonhomogeneous initial conditions like the reduced local surface density of contaminants after previous beam-showering. The dynamic analyses of this process might provide hints regarding the relative size of the contaminant molecules and also indicate some measures for the reduction of contamination growth.

Zerovalent scandium, zirconium, hafnium, and manganese nanoparticles are prepared by reduction of ScCl3, ZrCl4, HfCl4, and MnCl2 with lithium or sodium naphthalenide in a one-pot, liquid-phase synthesis. Small-sized monocrystalline nanoparticles are obtained with diameters of 2.4 +/- 0.2 nm (Sc), 4.0 +/- 0.9 nm (Zr), 8.0 +/- 3.9 nm (Hf) and 2.4 +/- 0.3 nm (Mn). Thereof, Zr(0) and Hf(0) nanoparticles with such size are shown for the first time. To probe the reactivity and reactions of the as-prepared Sc(0), Zr(0), Hf(0), and Mn(0) nanoparticles, they are exemplarily reacted in the liquid phase (e.g., THF, toluene, ionic liquids) with different sterically demanding, monodentate to multidentate ligands, mainly comprising O-H and N-H acidic alcohols and amines. These include isopropanol ((HOPr)-Pr-i), 1,1 '-bi-2-naphthol (H(2)binol), N,N '-bis(salicylidene)ethylenediamine (H(2)salen), 2-mercaptopyridine (2-Hmpy), 2,6-diisopropylaniline (H(2)dipa), carbazole (Hcz), triphenylphosphane (PPh3), N,N,N ',N '-tetramethylethylenediamine (tmeda), 2,2 '-bipyridine (bipy), N,N '-diphenylformamidine (Hdpfa), N,N '-(2,6-diisopropylphenyl)-2,4-pentanediimine ((dipp)(2)nacnacH), 2,2 '-dipydridylamine (Hdpa), and 2,6-bis(2-benzimidazolyl)pyridine (H(2)bbp). As a result, 22 new compounds are obtained, which frequently exhibit a metal center coordinated only by the sterically demanding ligand. Options and restrictions for the liquid-phase syntheses of novel coordination compounds using the oxidation of base-metal nanoparticles near room temperature are evaluated.

Porous organic materials have received increasing attention due to their potential applications, such as gas storage, gas separation, and catalysis. In this work, we present a series of aromatic, polyazide-containing building blocks that enable the formation of a new class of amorphous porous organic materials. The azide precursors are obtained in moderate to good yields following an easy synthesis procedure. By thermal decomposition, self-inflating porous structures named Azide Thermolysis Frameworks (ATFs) can be obtained. Modified thermogravimetric analysis is used to determine the onset temperature at which the azides decompose and the frameworks are formed. The frameworks are further investigated via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas adsorption measurements. Specific surface areas and pore sizes are determined by nitrogen adsorption measurements at 77 K using the Brunauer-Emmett-Teller method (BET) to give surface areas of up to 677 m2/g for the ATF resulting from the thermolysis of TPB-Azide at 450 degrees C, which can compete with early Covalent Organic Frameworks (COFs). The specific surface area can be tuned by varying the thermolysis temperature. A selection of aromatic azides is synthesized and thermolyzed to obtain self-inflating Azide Thermolyzed Frameworks (ATFs). ATFs with preferential 2D or 3D growth directions are obtained depending on the building blocks ' geometry. The molecular composition and properties of the ATFs are determined by BET, thermogravimetric analysis, IR, elemental analysis, and single electron microscopy.image

The design of a Cd-free and wider-bandgap buffer layer is stringent for future Cu(In,Ga)Se2 (CIGSe) thin-film solar cell applications. For that, an In2S3 buffer layer alloyed with a limited amount of O (well below 25 mol%) has been proposed as a pertinent alternative solution to CdS or Zn(O,S) buffers. However, the chemical stability of the In2S3/CIGSe heterointerface when O is added is not completely clear. Therefore, in this work, the buffer/absorber interface for a series of sputter-deposited In2S3 buffers with and without O is investigated. It is found that the solar cell with the highest open-circuit voltage is obtained for the O-free In2S3 buffer sputtered at 220 degrees C. This improved open-circuit voltage could be explained by the presence of a 20 nm-thick ordered vacancy compound (OVC) at the absorber surface. A much thinner OVC layer (5 nm) or even the absence of this layer is found for the cell with In2(O0.25S0.75)3 buffer layer where O is inserted. The volume fraction of the OVC layer is directly linked with the magnitude of Cu diffusion from the CIGSe surface into the In2(OxS1-x)3 buffer layer. The O addition strongly reduces the Cu diffusion inside the buffer layer up to complete suppression for very high O contents in the buffer. Finally, it is discussed that the presence of the OVC layer may lower the valence band maximum, thereby forming a hole barrier, suppressing charge carrier recombination at the In2(OxS1-x)3/CIGSe interface, which could result in an increased open-circuit voltage.

Journal Article Microstructure – Mechanical Property Relationship in Pristine and Aged Forsterite as a New Support Material for Solid Oxide Fuel Cells Get access Manuel Grudenik, Manuel Grudenik Materials Research Institute (IMFAA) — Aalen University, Aalen, Germany Search for other works by this author on: Oxford Academic Google Scholar Pinar Kaya, Pinar Kaya Materials Research Institute (IMFAA) — Aalen University, Aalen, Germany Corresponding author: pinar.kaya@hs-aalen.de Search for other works by this author on: Oxford Academic Google Scholar Matthias Meffert, Matthias Meffert Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany Search for other works by this author on: Oxford Academic Google Scholar Dagmar Gerthsen, Dagmar Gerthsen Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany Search for other works by this author on: Oxford Academic Google Scholar Piero Lupetin, Piero Lupetin Robert Bosch GmbH, Corporate Sector Research and Advance Engineering, Renningen, Germany Search for other works by this author on: Oxford Academic Google Scholar Michael J Hoffmann, Michael J Hoffmann Institute of Applied Materials — Ceramic Materials and Technologies (IAM-KWT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany Search for other works by this author on: Oxford Academic Google Scholar Volker Knoblauch Volker Knoblauch Materials Research Institute (IMFAA) — Aalen University, Aalen, Germany Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 29, Issue Supplement_1, 1 August 2023, Pages 1452–1453, https://doi.org/10.1093/micmic/ozad067.746 Published: 22 July 2023

Magnetic particle imaging (MPI) is a powerful and rapidly growing tomographic imaging technique that allows for the non-invasive visualization of superparamagnetic nanoparticles (NPs) in living matter. Despite its potential for a wide range of applications, the intrinsic quantitative nature of MPI has not been fully exploited in biological environments. In this study, a novel NP architecture that overcomes this limitation by maintaining a virtually unchanged effective relaxation (Brownian plus Néel) even when immobilized is presented. This superparamagnetic magnetite architecture made of phenolic resin hollow spheres coated with Eu(III) containing silica nanoparticles (SMARTH RHESINs) was synthesized and studied. Magnetic particle spectroscopy (MPS) measurements confirm their suitability for potential MPI applications. Photobleaching studies show an unexpected photodynamic due to the fluorescence emission peak of the europium ion in combination with the phenol formaldehyde resin (PFR). Cell metabolic activity and proliferation behavior are not affected. Colocalization experiments reveal the distinct accumulation of SMART RHESINs near the Golgi apparatus. Overall, SMART RHESINs show superparamagnetic behavior and special luminescent properties without acute cytotoxicity, making them suitable for bimodal imaging probes for medical use like cancer diagnosis and treatment. SMART RHESINs have the potential to enable quantitative MPS and MPI measurements both in mobile and immobilized environments.

The topological charge m of vortex electrons spans an infinite-dimensional Hilbert space. Selecting a two-dimensional subspace spanned by m=±1, a beam electron in a transmission electron microscope (TEM) can be considered as a quantum bit (qubit) freely propagating in the column. A combination of electron optical quadrupole lenses can serve as a universal device to manipulate such qubits at the experimenter's discretion. We set up a TEM probe forming lens system as a quantum gate and demonstrate its action numerically and experimentally. High-end TEMs with aberration correctors are a promising platform for such experiments, opening the way to study quantum logic gates in the electron microscope.

Zerovalent chromium nanoparticles (2.2. 0.2 nm in size) are prepared in the liquid phase (THF) by reduction of CrCl2 with lithium naphthalenide ([LiNaph]). The deep black Cr(0) nanoparticle suspensions in THF are colloidally and chemically highly stable. On the other hand, the Cr(0) nanoparticles are highly reactive, e. g., when in contact to O-2, H2O, or other oxidizing agents. To probe the reactivity of the Cr(0) nanoparticles in the liquid phase near room temperature (50-80 degrees C), they are reacted with different coordinatively demanding, N H, S H or O H acidic reactants. This includes the amines 2,2 '-dipyridylamine (HDPA), 2-(1H-imidazol-2-yl)pyridine (HImPy) and carbazole (HCbz), the thiol 2-mercaptopyridine (HMPy), and benzoic acid (HBz) as a carboxylate. As a result, the five novel compounds [Cr(DPA)(3)], [Cr(ImPy)(3)] center dot HImPy, [Cr(MPy)(3)] center dot 0.5 Tol (Tol: toluene), [Na2Cr(Cbz)(4)(THF)(3)], and [Cr-2(Bz)(4)(THF)(2)] are obtained. [Cr(DPA)(3)] and [Cr(ImPy)(3)] center dot HImPy show Cr(III) coordinated by nitrogen only; [Cr(MPy)(3)] center dot 0.5 Tol shows a coordination of Cr(III) by both N and S atoms. [Na2Cr(Cbz)(4)(THF)(3)] and [Cr-2(Bz)(4)(THF)(2)] contain Cr(II) and exhibit an infinite chain-like structure and pairs of chromium atoms with fourfold binding.

Analytical TEM study of the rare-earth element (REE) intermixing between different REBa 2 Cu 3 O 7− δ samples with embedded BaHfO 3 nanoparticles. REEs with smaller ionic radii are incorporated with higher concentrations in BaHfO 3 .

Energy-dispersive X-ray spectroscopy (EDXS) in a transmission electron microscope is frequently used for the chemical analysis of Cu(In,Ga)Se2 (CIGS) solar cells with high spatial resolution. However, the quantification of EDXS data is complicated due to quantification errors and artifacts. This work shows how quantitative EDXS analyses of CIGS-based solar cells with Zn(O,S) buffer and ZnO-based window layers can be significantly improved. For this purpose, CIGS-based solar cells and a reference sample with a stack of Zn(O,S) layers with different [O]/[S] ratios were analyzed. For Zn(O,S), the correction of sample-thickness-dependent absorption of low-energy O–Kα X-rays significantly improves the results of quantitative EDXS. Absorption of characteristic X-rays in CIGS is less relevant. However, for small transmission electron microscopy (TEM) sample thicknesses, artifacts can occur due to material changes by focused-ion-beam (FIB)-based preparation of TEM samples, electron-beam-induced damage, and oxidation of the sample surface. We also show that a Pt-protection layer, deposited on the sample surface before FIB preparation of TEM lamellae, can induce artifacts that can be avoided by first depositing a carbon layer.

The cover shows chromium nanoparticles for reactions with different O−H, S−H or N−H acidic ligands in the liquid phase (THF) near room temperature (<100 °C) to obtain novel coordination compounds. (DOI: 10.1002/zaac.202300137)

In functional ceramics, the impact of dopants on bulk crystals is generally well understood. Their impact on grain boundaries is less well known. The present study investigates the impact of acceptor dopants on grain growth in strontium titanate. Scanning electron microscopy and analytical (scanning) transmission electron microscopy have been used to gain knowledge on Fe segregation behavior, grain sizes, and grain size distributions of SrTiO3. While undoped microstructures show normal grain growth at low temperatures (<1350 degrees C), doped micro-structures evolve bimodally. With increasing acceptor dopant concentration, an increasing population of small grains develops. It is shown that Fe segregates to the grain boundaries due to its negative charge and a positive boundary potential. Thus, the experimental findings seem to be well explained by the theory of solute drag: The diffusion of segregated defects ('solutes') at grain boundaries can retard grain boundary migration.

Short-wave infrared (SWIR) fluorescence could become the new gold standard in optical imaging for biomedical applications due to important advantages such as lack of autofluorescence, weak photon absorption by blood and tissues, and reduced photon scattering coefficient. Therefore, contrary to the visible and NIR regions, tissues become translucent in the SWIR region. Nevertheless, the lack of bright and biocompatible probes is a key challenge that must be overcome to unlock the full potential of SWIR fluorescence. Although rare-earth-based core-shell nanocrystals appeared as promising SWIR probes, they suffer from limited photoluminescence quantum yield (PLQY). The lack of control over the atomic scale organization of such complex materials is one of the main barriers limiting their optical performance. Here, the growth of either homogeneous (α-NaYF 4 ) or heterogeneous (CaF 2 ) shell domains on optically-active α-NaYF 4 :Yb:Er (with and without Ce 3+ co-doping) core nanocrystals is reported. The atomic scale organization can be controlled by preventing cation intermixing only in heterogeneous core-shell nanocrystals with a dramatic impact on the PLQY. The latter reached 50% at 60 mW/cm 2 ; one of the highest reported PLQY values for sub-15 nm nanocrystals. The most efficient nanocrystals were utilized for in vivo imaging above 1450 nm.

FIB-SEM measurements of as-processed Ni-YSZ solid oxide fuel cell (SOFC) anodes are conducted. Based on the reconstructed volume as initial condition, multiphase-field simulations of nickel coarsening are performed to investigate the microstructure under operating conditions. The effect of the wettability of nickel on YSZ is discussed to span a possible range of different operating conditions. Effective properties including nickel particle size distributions, mean particle diameters, tortuosities and triple-phase boundary lengths (TPBL) serve as quantitative indicators for possible degradation and failure. The resulting data is used in a transmission-line model (TLM) to estimate anode performance and long-term stability. Generally, the simulations show that Ni coarsening at 750°C takes place mainly in the first 100 hours. It is found that nickel coarsening is enhanced when nickel shows dewetting on YSZ. Among other findings, the TPBL decreases significantly during the simulations for all parameter sets and is insusceptible to variations in wetting angle. The TLM considers the reduction of TPBL as the main factor for degradation. Loss of nickel connectivity can lead to a further significant drop in anode performance occurring predominantly for low wettability of nickel on YSZ.