Small Cations Research Articles

Investigation of properties and performance of three novel highly concentrated ether-functionalised ionic liquid electrolytes for lithium metal batteries

Exploring highly concentrated (>50 mol% Li-salt) ionic liquids as electrolytes for lithium metal batteries can lead to the development of safer, high-performance batteries with increased energy density and improved cycling stability. However, at high concentrations of Li-salt, ionic liquid electrolytes can have high viscosity and slow ion transport kinetics. Here, we investigate the use of novel ether-functionalised cations as a promising approach for increasing fluidity and weakening Li+-anion interactions in highly concentrated ionic liquid electrolytes to facilitate faster transport of Li+. Three small ether-functionalised cations, namely 1-methoxymethyl-1,1,1-trimethylammonium ([N111,1O1]+), N-methoxymethyl-N-methylpiperidinium ([C1O1mpip]+) and N-methoxymethyl-N-methylmorpholinium ([C1O1mmor]+) are compared when paired with bis(fluorosulfonyl)imide ([FSI]−) anion at a 1:1 mol ratio with LiFSI. The study provides insights into the relationship between the structure of the ether-functionalised cations and the properties of the resulting electrolytes, including thermal behaviour, ionic conductivity, viscosity, ion diffusivity, Li plating/stripping behaviour and Li+-transference number. The performance of the electrolytes was tested in Li|LiFePO4 (LFP) cells (1.14 mAh cm−2) at 0.57 mA cm−2 (C/2) for 100 cycles at 50 °C. (LiFSI)0.5([C1O1mpip][FSI])0.5 and (LiFSI)0.5([N111,1O1][FSI])0.5, have high Li-transference numbers of 0.47 ± 0.02 and 0.37 ± 0.02, respectively, and both display 0.85 mAh cm−2 areal discharge capacity after 100 cycles, with capacity retention over 98.5% (in comparison to the first cycle after preconditioning cycles), demonstrating the feasibility of these electrolytes in Li-metal cells.

Reversible Intercalation of Protons in Tungsten Oxide Films for Multi-Transduction Sensor Applications

Tungsten oxide films under electrochemical bias, can form tungsten oxide bronzes (MxWO3 with M being small cations such as H+ or Li+) featuring high electronic conductivity and change in coloration to deep blue1. This doping process occurs through the reduction of W6+, as described by the following equation:WO3 + x H+ + xe- -> HxWO3The bronze phase can also be formed through exposure of tungsten oxide to H2 at high temperatures (> 200 oC) or in presence of catalysts2, as described by the following equation:WO3 + x/2 H2 -> HxWO3 Because of the significant changes in both optical and electrical proprieties of the films, electrochemical control of proton doping can be used as a strategy for the development of ion-gated transistors3,4, hydrogen sensors and smart windows5.In this work, we report the use of thin films prepared by sol-gel synthesis using polyperoxotungstic acid (PPTA) as a precursor. We used three different types of substrates (conductive transparent fluorine-doped tin oxide (FTO) glass, Si/SiO2 patterned with Au source-drain electrodes and Interdigitated electrodes patterned on transparent glass) to study the changes of color and conductivity following the formation of the bronze in both electrochemical and dry environments. In electrochemical environment, we show that gating by ionic liquid in transistor configuration can be used to propose an iontronic sensor to detect H2 and H2O6. In dry environment, we show that simultaneous monitoring of visible light transmittance and electrical conductivity can be used a double transducer for H2 sensors6.1 M. S. Whittingham, in Solid State Ionics, 2004, vol. 168, pp. 255–263.2 C. C. Chan, W. C. Hsu, C. C. Chang and C. S. Hsu, Sensors and Actuators, B: Chemical, 2011, 157, 504–509.3 M. Barbosa, X. Meng, F. Soavi, C. Santato and M. O. Orlandi, J Mater Chem C Mater, 2018, 6, 1980–1987.4 G. V. de Oliveira Silva, A. Subramanian, X. Meng, S. Zhang, M. S. Barbosa, B. Baloukas, D. Chartrand, J. C. Gonzáles, M. O. Orlandi, F. Soavi, F. Cicoira and C. Santato, J Phys D Appl Phys,5 G. Cai, J. Wang and P. S. Lee, Acc Chem Res, 2016, 49, 1469–1476.6 M. S. Barbosa, R. A. da Silva, C. Santato and M. O. Orlandi, Journal of Vacuum Science & Technology A, 2022, 40, 013202.

Improving the Nitrogen Reduction Reaction Activity of Ti2n Nitride Mxene through pH and Electrolyte Selection

Electrochemical nitrogen reduction reaction (NRR) is used to convert atmospheric nitrogen (N2) to ammonia (NH3) at ambient temperature and pressure. In general, acidic electrolytes are used to provide protons (H+) for the reduction process. However, this leads to a low NH3 selectivity because of H2 by-product formation via the hydrogen evolution reaction (HER). Recently, we showed that a Ti2N MXene is active and selective for NRR. We demonstrated that this catalyst works through a Mars-van Krevelen (MvK) mechanism rather than the conventional associative/dissociative mechanisms. However, the effect of pH and electrolyte on its catalytic activity and selectivity was not well understood. Here, we investigate these effects by performing experiments in varying electrolytic conditions and develop relations between pH, electrolyte choice, and performance. The Ti2N nitride MXene was synthesized via an oxygen-assisted molten salt fluoride etching technique and characterized through XRD and Raman and FTIR spectroscopies. Our findings showed that changing pH does not affect the NRR onset potential. We found that as pH increases, selectivity towards NH3 also increases presumably due to a lack of free H+ available to participate in HER. We also found that smaller cations with smaller solvation shells suppress HER activity, while smaller anions prevent catalyst poisoning during the NRR process, as evidenced by cyclic voltammetry before and after experimental conditions. We confirm production rates and the method of NH3 formation via NMR analytical techniques, including isotopic exchange. We plan to expand these findings to other materials and systems, and use the knowledge obtained from these studies to design optimal electrolytic conditions to produce NH3 through NRR.

“Ca2+-dependent regulation of the proton permeability of the inner membrane of lupine cotyledon mitochondria”

change in volume, and proton permeability of the inner membrane of mitochondria isolated from cotyledons of etiolated seedlings of narrow-leaved lupine (Lupinus angustifolius L.) was studied. The mitochondria used in the work were characterized by a strong coupling of oxidation and phosphorylation processes. The high functional activity of mitochondria was confirmed by their ability to generate a transmembrane gradient of protons on the inner membrane (membrane potential or ∆Ψ) during the oxidation of succinate and also sustainably maintain it for a long time , both due to the operation of the electron transport chain and due to ATP hydrolysis under conditions of anaerobiosis. It was shown that the presence of 60–120 µM CaCl2 in the mitochondrial incubation medium had no significant effect on the rate of succinate oxidation and the parameters of oxidative phosphorylation; however, it induced ∆Ψ dissipation under conditions of oxygen depletion in the incubation medium. The most complete removal Ca2+ from the medium in the presence of chelators (EGTA, EDTA) prevented the membrane potential dissipation. Ca2+-dependent depolarization of the inner membrane was inhibited by dithiothreitol, suggesting involvement in this process of reactive oxygen species. The reset of the membrane potential was not accompanied by swelling of mitochondria and was not sensitive to cyclosporine A. Using metallochromic Ca2+-indicator arsenazo III, it was shown that the mitochondria of lupine cotyledons are able to actively absorb exogenous Ca2+ and store it in the matrix. Ca2+-induced dissipation of ∆Ψ under conditions of anaerobiosis was accompanied by the release of Ca2+ from mitochondria, the rate of which sharply increased in the presence of calcium ionophore A23 (A23187). It is assumed that the accumulation of Ca2+ and an increase in the level of reactive oxygen species in the matrix induces reversible permeabilization of the inner mitochondrial membrane of lupine cotyledons under conditions of anaerobiosis, which is due to the opening of a pore of nonspecific permeability in a state of low conductivity permeable to protons and, possibly, to other small cations (Na+, K+, Ca2+).

Quantifying and Reducing Ion Migration in Metal Halide Perovskites through Control of Mobile Ions.

The presence of intrinsic ion migration in metal halide perovskites (MHPs) is one of the main reasons that perovskite solar cells (PSCs) are not stable under operation. In this work, we quantify the ion migration of PSCs and MHP thin films in terms of mobile ion concentration (No) and ionic mobility (µ) and demonstrate that No has a larger impact on device stability. We study the effect of small alkali metal A-site cation additives (e.g., Na+, K+, and Rb+) on ion migration. We show that the influence of moisture and cation additive on No is less significant than the choice of top electrode in PSCs. We also show that No in PSCs remains constant with an increase in temperature but μ increases with temperature because the activation energy is lower than that of ion formation. This work gives design principles regarding the importance of passivation and the effects of operational conditions on ion migration.

Unraveling the Mechanism of Alkali Metal Fluoride Post-Treatment of SnO2 for Efficient Planar Perovskite Solar Cells.

The facile synthesis and beneficial properties of tin oxide have driven the development of efficient planar perovskite solar cells (PSCs). To increase the PSC performance, alkali salts are used to treat the SnO2 surface to minimize the defect states. However, the underlying mechanism of alkali cations' role in the PSCs needs further exploration. Herein the effect of alkali fluoride salts (KF, RbF, and CsF) on the properties of SnO2 and PSC performance is investigated. The results show different alkali have significant roles depending on their nature. Larger cations Cs+ preferably locate at the SnO2 film surface to passivate surface defects and enhance conductivity, while smaller cations like Rb+ or K+ cations tend to diffuse into the perovskite layer to reduce trap density of the material. The former effect leads to enhanced fill factor while the latter effect increases the open circuit voltage of the device. It is then demonstrated that a dual cation post-treatment of the SnO2 layer with RbF and CsF achieves PSC with a significantly higher power conversion efficiency (PCE) of 21.66% compared to pristine PSC with a PCE of 19.71%. This highlights the significance of defect engineering of SnO2 using selective multiple alkali treatment to improve PSC performance.

Front-contact passivation through 2D/3D perovskite heterojunctions enables efficient bifacial perovskite/silicon tandem solar cells

•Non-uniform formation of n = 2 is more dominant for iso-BAI-passivated perovskite •Bifacial perovskite/Si tandem devices exhibited power generation density >27 mW cm−2 •Shorter spacer iso-BA reduced the charge accumulation at thinner quantum wells •Branched BA-based 2D perovskite formation resulted in JSC as high as 22.8 mA cm−2 Surface passivation by thin-slab 2D perovskites is an effective method to suppress interfacial carrier recombination of 3D metal halide perovskite photoabsorbers. However, improving device performance by integrating such 2D/3D perovskite heterojunctions in the sunward, transparent contacts of perovskite solar cells is not evident due to the high exciton binding energies of phase-pure 2D perovskites, which may result in inefficient free-carrier generation and collection. Here, we overcome this challenge by tuning the dimensionality of 2D perovskites via structural isomers of butylammonium (BA) as a small organic cation, occupying the A-site of the 2D perovskite lattice. The discontinuous iso-BA-based 2D crystals on the 3D perovskite surface yield improved interfacial passivation and enhanced hole extraction. Besides an increased open circuit voltage, this remarkably leads to an enhanced photocurrent (∼1 mA cm−2) compared with control perovskite solar cells, resulting in bifacial perovskite/silicon tandem solar cells with power generation densities >27 mW cm−2. Surface passivation by thin-slab 2D perovskites is an effective method to suppress interfacial carrier recombination of 3D metal halide perovskite photoabsorbers. However, improving device performance by integrating such 2D/3D perovskite heterojunctions in the sunward, transparent contacts of perovskite solar cells is not evident due to the high exciton binding energies of phase-pure 2D perovskites, which may result in inefficient free-carrier generation and collection. Here, we overcome this challenge by tuning the dimensionality of 2D perovskites via structural isomers of butylammonium (BA) as a small organic cation, occupying the A-site of the 2D perovskite lattice. The discontinuous iso-BA-based 2D crystals on the 3D perovskite surface yield improved interfacial passivation and enhanced hole extraction. Besides an increased open circuit voltage, this remarkably leads to an enhanced photocurrent (∼1 mA cm−2) compared with control perovskite solar cells, resulting in bifacial perovskite/silicon tandem solar cells with power generation densities >27 mW cm−2.

Polyamines and Physical Activity in Musculoskeletal Diseases: A Potential Therapeutic Challenge.

Autophagy dysregulation is commonplace in the pathogenesis of several invalidating diseases, such as musculoskeletal diseases. Polyamines, as spermidine and spermine, are small aliphatic cations essential for cell growth and differentiation, with multiple antioxidant, anti-inflammatory, and anti-apoptotic effects. Remarkably, they are emerging as natural autophagy regulators with strong anti-aging effects. Polyamine levels were significantly altered in the skeletal muscles of aged animals. Therefore, supplementation of spermine and spermidine may be important to prevent or treat muscle atrophy. Recent in vitro and in vivo experimental studies indicate that spermidine reverses dysfunctional autophagy and stimulates mitophagy in muscles and heart, preventing senescence. Physical exercise, as polyamines, regulates skeletal muscle mass inducing proper autophagy and mitophagy. This narrative review focuses on the latest evidence regarding the efficacy of polyamines and exercise as autophagy inducers, alone or coupled, in alleviating sarcopenia and aging-dependent musculoskeletal diseases. A comprehensive description of overall autophagic steps in muscle, polyamine metabolic pathways, and effects of the role of autophagy inducers played by both polyamines and exercise has been presented. Although literature shows few data in regard to this controversial topic, interesting effects on muscle atrophy in murine models have emerged when the two "autophagy-inducers" were combined. We hope these findings, with caution, can encourage researchers to continue investigating in this direction. In particular, if these novel insights could be confirmed in further in vivo and clinical studies, and the two synergic treatments could be optimized in terms of dose and duration, then polyamine supplementation and physical exercise might have a clinical potential in sarcopenia, and more importantly, implications for a healthy lifestyle in the elderly population.

Reactivity of Rare-Earth Oxides in Anhydrous Imidazolium Acetate Ionic Liquids

Rare-earth metal sesquioxides (RE2O3) are stable compounds that require high activation energies in solid-state reactions or strong acids for dissolution in aqueous media. Alternatively, dissolution and downstream chemistry of RE2O3 have been achieved with ionic liquids (ILs), but typically with additional water. In contrast, the anhydrous IL 1-butyl-3-methylimidazolium acetate [BMIm][OAc] dissolves RE2O3 for RE = La–Ho and forms homoleptic dinuclear metal complexes that crystallize as [BMIm]2[RE2(OAc)8] salts. Chloride ions promote the dissolution without being included in the compounds. Since the lattice energy of RE2O3 increases with decreasing size of the RE3+ cation, Ho2O3 dissolves very slowly, while the sesquioxides with even smaller cations appear to be inert under the applied conditions. The Sm and Eu complex salts show blue and red photoluminescence and Van Vleck paramagnetism. The proton source for the dissolution is the imidazolium cation. Abstraction of the acidic proton at the C2-atom yields an N-heterocyclic carbene (imidazole-2-ylidene). The IL can be regenerated by subsequent reaction with acetic acid. In the overall process, RE2O3 is dissolved by anhydrous acetic acid, a reaction that does not proceed directly.

Ion Effects on the Performance of the Single‐Layer Organic Light‐Emitting Devices Based on Adding Salt Additives

The single‐layer organic light‐emitting devices provide a promising way for low‐cost, large‐area displays. Iridium (III) complex may play an important role to achieve this target due to its unique ionic characteristics. To achieve high‐performance single‐layer devices, blending the salt additives into the active layer is an effective strategy. However, the effects of different cation and anion additives on the device's performance are still unclear. Herein, the single‐layer light‐emitting devices are fabricated by using solution‐processed iridium (III) complex mixed with various molecular salts. It is implied in the results that the improvement of the device luminescence and recombination efficiency is owing to the enhanced carrier injection and improved carrier balance in the emitting layer by the ion‐additive‐induced electrical double layer at the interface. The smaller cation can improve the carrier injection of the device more efficiently due to the stronger ion mobility and the anion with the smaller association coefficient shows a better device performance since the stronger dissociation ability of the ions can lead to a better ion migration ability. In addition, the introduction of poly (methyl methacrylate) into the active film can improve the single‐layer device performances by reducing leak current in bulk.

Superior ferroelectricity and nonlinear optical response in a hybrid germanium iodide hexagonal perovskite

Abundant chemical diversity and structural tunability make organic–inorganic hybrid perovskites (OIHPs) a rich ore for ferroelectrics. However, compared with their inorganic counterparts such as BaTiO3, their ferroelectric key properties, including large spontaneous polarization (Ps), low coercive field (Ec), and strong second harmonic generation (SHG) response, have long been great challenges, which hinder their commercial applications. Here, a quasi-one-dimensional OIHP DMAGeI3 (DMA = Dimethylamine) is reported, with notable ferroelectric attributes at room temperature: a large Ps of 24.14 μC/cm2 (on a par with BaTiO3), a low Ec below 2.2 kV/cm, and the strongest SHG intensity in OIHP family (about 12 times of KH2PO4 (KDP)). Revealed by the first-principles calculations, its large Ps originates from the synergistic effects of the stereochemically active 4s2 lone pair of Ge2+ and the ordering of organic cations, and its low kinetic energy barrier of small DMA cations results in a low Ec. Our work brings the comprehensive ferroelectric performances of OIHPs to a comparable level with commercial inorganic ferroelectric perovskites.

Evaluation of Molecular Fragmentation in Polycyclic Aromatic Hydrocarbons by Time-of-Flight Secondary Ion Mass Spectrometry

In time-of-flight secondary ion mass spectrometry (TOF-SIMS), ionized molecules and molecular fragments (secondary ions) are generated in collisions of high-energy ions (primary ions) with a solid sample surface. Mass spectra of the emitted secondary ions are typically used to identify molecular species and to determine their spatial distribution on the sample surface. Here, we extend this application in a TOF-SIMS study of a series of polycyclic aromatic hydrocarbons (PAHs) where we focus on the fragmentation of these molecules, with the purpose of better understanding the fragmentation patterns of heavy aromatic molecules in petroleum. For all PAHs, the collision process generated (i) a series of smaller cation fragments and (ii) cations close in size to the original PAH (molecular cations). Stark differences are measured for various PAHs regarding the abundance of smaller fragments versus molecular cations. Observation of hydrogen-deficient (H-deficient) cation fragments indicates the formation of polyynes and allenes. For PAHs producing higher fractions of small cation fragments, these ions are surprisingly hydrogen rich (H-rich). The H/C ratio of fragments does not scale with the fraction of Clar sextet carbon, nor with energies of low-lying electronic transitions. Free radical cation fragments tend to be suppressed. For sufficiently large fragments, aromatic cations appear to be formed and include some free radical aromatics. There is ample production of molecular ions with loss of a single carbon atom or a methine group, which corresponds to the reduction of a 6-membered aromatic ring to a 5-membered ring. There is some enhancement of free radical molecular cations due to the corresponding formation of neutral polyynes. Fragment anions are also produced with a strong preference for very H-deficient carbon clusters, in some cases being the same as carbon cluster anions observed in space. Comparisons of PAH TOF-SIMS spectra with those of asphaltenes are discussed in detail.

Cooling dynamics of energized naphthalene and azulene radical cations.

Naphthalene and azulene are isomeric polycyclic aromatic hydrocarbons (PAHs) and are topical in the context of astrochemistry due to the recent discovery of substituted naphthalenes in the Taurus Molecular Cloud-1 (TMC-1). Here, the thermal- and photo-induced isomerization, dissociation, and radiative cooling dynamics of energized (vibrationally hot) naphthalene (Np+) and azulene (Az+) radical cations, occurring over the microsecond to seconds timescale, are investigated using a cryogenic electrostatic ion storage ring, affording "molecular cloud in a box" conditions. Measurement of the cooling dynamics and kinetic energy release distributions for neutrals formed through dissociation, until several seconds after hot ion formation, are consistent with the establishment of a rapid (sub-microsecond) Np+ ⇌ Az+ quasi-equilibrium. Consequently, dissociation by C2H2-elimination proceeds predominantly through common Az+ decomposition pathways. Simulation of the isomerization, dissociation, recurrent fluorescence, and infrared cooling dynamics using a coupled master equation combined with high-level potential energy surface calculations [CCSD(T)/cc-pVTZ], reproduce the trends in the measurements. The data show that radiative cooling via recurrent fluorescence, predominately through the Np+ D0 ← D2 transition, efficiently quenches dissociation for vibrational energies up to ≈1eV above dissociation thresholds. Our measurements support the suggestion that small cations, such as naphthalene, may be more abundant in space than previously thought. The strategy presented in this work could be extended to fingerprint the cooling dynamics of other PAH ions for which isomerization is predicted to precede dissociation.

P2X receptors in GtoPdb v.2023.1

P2X receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on P2X Receptors [49, 146]) have a trimeric topology [118, 128, 144, 197] with two putative TM domains per P2X subunit, gating primarily Na+, K+ and Ca2+, exceptionally Cl-. The Nomenclature Subcommittee has recommended that for P2X receptors, structural criteria should be the initial basis for nomenclature where possible. X-ray crystallography indicates that functional P2X receptors are trimeric and three agonist molecules are required to bind to a single trimeric assembly in order to activate it [118, 144, 95, 103, 177]. Native receptors may occur as either homotrimers (e.g. P2X1 in smooth muscle) or heterotrimers (e.g. P2X2:P2X3 in the nodose ganglion [280], P2X1:P2X5 in mouse cortical astrocytes [162], and P2X2:P2X5 in mouse dorsal root ganglion, spinal cord and mid pons [53, 234]. P2X2, P2X4 and P2X7 receptor activation can lead to influx of large cationic molecules, such as NMDG+, Yo-Pro, ethidium or propidium iodide [211]. The permeability of the P2X7 receptor is modulated by the amount of cholesterol in the plasma membrane [193]. The hemi-channel pannexin-1 was initially implicated in the action of P2X7 [212], but not P2X2, receptors [41], but this interpretation is probably misleading [215]. Convincing evidence now supports the view that the activated P2X7 receptor is immediately permeable to large cationic molecules, but influx proceeds at a much slower pace than that of the small cations Na+, K+, and Ca2+ [66].

Analysis of gene expression related to polyamine concentration and dimorphism induced in ornithine decarboxylase (odc) and spermidine synthase (spd) Ustilago maydis mutants

Polyamines are ubiquitous small organic cations, and their roles as regulators of several cellular processes are widely recognized. They are implicated in the key stages of the fungal life cycle. Ustilago maydis is a phytopathogenic fungus, the causal agent of common smut of maize and a model system to understand dimorphism and virulence. U. maydis grows in yeast form at pH 7 and it can develop its mycelial form in vitro at pH 3. Δodc mutants that are unable to synthesize polyamines, grow as yeast at pH 3 with a low putrescine concentration, and to complete its dimorphic transition high putrescine concentration is require. Δspd mutants require spermidine to grow and cannot form mycelium at pH 3. In this work, the increased expression of the mating genes, mfa1 and mfa2, on Δodc mutants, was related to high putrescine concentration. Global gene expression analysis comparisons of Δodc and Δspd U. maydis mutants indicated that 2,959 genes were differentially expressed in the presence of exogenous putrescine at pH 7 and 475 genes at pH 3. While, in Δspd mutant, the expression of 1,426 genes was affected by exogenous spermine concentration at pH 7 and 11 genes at pH 3. Additionally, we identified 28 transcriptional modules with correlated expression during seven tested conditions: mutant genotype, morphology (yeast, and mycelium), pH, and putrescine or spermidine concentration. Furthermore, significant differences in transcript levels were noted for genes in modules relating to pH and genotype genes involved in ribosome biogenesis, mitochondrial oxidative phosphorylation, N-glycan synthesis, and Glycosylphosphatidylinositol (GPI)-anchor. In summary, our results offer a valuable tool for the identification of potential factors involved in phenomena related to polyamines and dimorphism.

Controlled Growth of Hybrid Halide Perovskites by Crown Ether Complexation for Perovskite Solar Cells

AbstractHost‐guest complexation has demonstrated potential for controlling hybrid organic‐inorganic metal halide perovskite materials. In particular, crown ethers have been used due to their capacity to interact with metal cations (e. g., Pb2+) and small organic cations (e. g., methylammonium (MA)), which can affect hybrid perovskite materials and their solar cells. However, this strategy has been underexploited in perovskite photovoltaics, and the underlying mechanisms are not well understood. In this study, we investigate the influence of 15‐crown‐5 (15C5) and its benzannulated derivative (benzo‐15‐crown‐5, B15C5), as well as amino‐functionalized analogues (15‐crown‐5)‐2‐methylamine, 2A‐15C5, and 4′‐aminobenzo‐15‐crown‐5, 4A‐B15C5, on MAPbI3 perovskite crystallization and inverted solar cell performance. We demonstrate the propensity of crown ether modulators to interact with Pb2+ cations at the perovskite interface by density functional theory calculations. This has been shown to facilitate oriented crystal growth and homogeneous film formation, as revealed by X‐ray diffraction analysis complemented by scanning electron microscopy. As a result, we demonstrate an increase in the power conversion efficiency of the solar cells of interest to advancing hybrid photovoltaics.

Structural Insights into Layered Tetrahalocuprates(II) Based on Small Unsaturated and Cyclic Primary Ammonium Cations.

Layered hybrid halometallates represent a promising class of multifunctional materials, yet with many open challenges regarding the interaction between building blocks. In this work, we present a synthetic and analytical methodology for the efficient synthesis and structural analysis of a series of novel tetrahalocuprate(II) hybrids based on small alkylammonium cations. Observed robustness in geometrical motifs provided a platform for crystal structure determination, even from the complex laboratory powder diffraction data. The slight differences in inorganic layer geometry and severe differences in organic bilayer packing are quantified using well-established descriptors for these materials, and dependences of geometric parameters on anion and cation choice are accounted for. Temperature dependence of structural parameters for one of the tetrachlorocuprate hybrids that was chosen as a model unveils a possible geometrical origin of thermochromism in these materials.

Efficiency enhancement of dye-sensitized solar cell with PVdF-HFP:MPII:NaI quasi-solid-state electrolyte

Quasi-solid-state polymer electrolyte (QSSPE) based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) was prepared using sodium iodide (NaI) salt, 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid, propylene carbonate (PC) and 1,2-dimethoxyethane (DME) plasticizers. This paper discusses the effects of using a binary mixture of large (MPII) and small (NaI) cation alkaline salts on enhancing the performance of DSSCs with gel polymer electrolytes. The amount of NaI was varied while the other components were kept constant to study the dependence of dye-sensitized solar cell (DSSC) performance on NaI amount. The incorporation of NaI in PVdF-HFP-MPII-PC-DME has enhanced the efficiency of DSSC. DSSC with 0.6 M MPII and 0.4 M NaI showed the highest efficiency of 4.16 % and short circuit current density (J sc) of 13.63 mAcm−2. Additionally, the roles of TBP and GuSCN as co-additives in the electrolytes were also discussed in this paper. The presence of 4-tert-butylpyridine (TBP) and guanidine thiocyanate (GuSCN) further enhanced the efficiency from 4.16 to 6.95 %.

Ferrimagnetic Ordering and Spin-Glass State in Diluted GdFeO3-Type Perovskites (Lu0.5Mn0.5)(Mn1-xTix)O3 with x = 0.25, 0.50, and 0.75.

ABO3 perovskite materials with small cations at the A site, especially those with ordered cation arrangements, have attracted a great deal of interest because they show unusual physical properties and deviations from the general characteristics of perovskites. In this work, perovskite solid solutions (Lu0.5Mn0.5)(Mn1-xTix)O3 with x = 0.25, 0.50, and 0.75 were synthesized by means of a high-pressure, high-temperature method at approximately 6 GPa and approximately 1550 K. All the samples crystallize in the GdFeO3-type perovskite structure (space group Pnma) and have random distributions of the small Lu3+ and Mn2+ cations at the A site and Mn4+/3+/2+ and Ti4+ cations at the B site, as determined by Rietveld analysis of high-quality synchrotron X-ray powder diffraction data. Lattice parameters are a = 5.4431 Å, b = 7.4358 Å, c = 5.1872 Å (for x = 0.25); a = 5.4872 Å, b = 7.4863 Å, c = 5.2027 Å (for x = 0.50); and a = 5.4772 Å, b = 7.6027 Å, c = 5.2340 Å (for x = 0.75). Despite a significant dilution of the A and B sublattices by non-magnetic Ti4+ cations, the x = 0.25 and 0.50 samples show long-range ferrimagnetic order below TC = 89 K and 36 K, respectively. Mn cations at both A and B sublattices are involved in the long-range magnetic order. The x = 0.75 sample shows a spin-glass transition at TSG = 6 K and a large frustration index of approximately 22. A temperature-independent dielectric constant was observed for x = 0.50 (approximately 32 between 5 and 150 K) and for x = 0.75 (approximately 50 between 5 and 250 K).

A2Zr2O7 (A=La/Gd/Yb): Grain growth effect on phase stability properties at 1300°C

The present study aims to investigate the influence of grain growth during heat treatment on the phase stability of AZO: A2Zr2O7 compounds at 1300°C. To this end, three cations of La3+, Gd3+, and Yb3+ (corresponding to large, medium and small cations, respectively) were placed in the A-site of the AZO compounds through co-precipitation–calcination technique at 1000°C for 3 h to achieve LaZO: La2Zr2O7, GdZO: Gd2Zr2O7, and YbZO: Yb2Zr2O7, respectively. The phase stability of LaZO, GdZO, and YbZO was assessed under 50 h of heat treatment at 1300°C. Characterization techniques such as conventional and high-temperature XRD, Raman and Fourier transform infrared (FTIR) spectroscopies, simultaneous thermal analysis (DTA/TG), and field-emission scanning electron microscopy (FESEM) were employed to assess the synthesized compounds. FESEM results of LaZO, GdZO and YbZO calcinated powders indicated orderly particles, uniform in shape and size, with a relative tendency of agglomeration and with an average particle size of less than ∼100 nm. XRD results of LaZO and YbZO powders after calcination indicated the formation of pyrochlore and defect fluorite structures, respectively. The placement of Gd3+ (GdZO) led to the formation of a dual pyrochlore-defect fluorite structure. The current research also indicated an enhancement in the tendency to form pyrochlore structure in GdZO and YbZO compounds along with the growth of the grains after 20 (mean grain size of ∼250 nm) and 50 h (mean grain size of ∼800 nm) of exposure to the temperature of 1300°C, respectively.