In the search for novel battery systems with high energy density and low cost, fluoride ion batteries have recently emerged as a further option to store electricity with very high volumetric energy densities. Among metal fluorides, CuF 2 is an intriguing candidate for cathode materials due to its high specific capacity and high theoretical conversion potential. Here, the reversibility of CuF 2 as a cathode material in the fluoride ion battery system employing a high F − conducting tysonite-type La 0.9 Ba 0.1 F 2.9 as an electrolyte and a metallic La as an anode is investigated. For the first time, the reversible conversion mechanism of CuF 2 with the corresponding variation in fluorine content is reported on the basis of X-ray photoelectron spectroscopy measurements and cathode/electrolyte interfacial studies by transmission electron microscopy. Investigation of the anode/electrolyte interface reveals structural variation upon cycling with the formation of intermediate layers consisting of i) hexagonal LaF 3 and monoclinic La 2 O 3 phases in the pristine interface;ii) two main phases of distorted orthorhombic LaF 3 and monoclinic La 2 O 3 after discharging; and iii) a tetragonal lanthanum oxyfluoride (LaOF) phase after charging. The fading mechanism of the cell capacity upon cycling can be explained by Cu diffusion into the electrolyte and side reactions due to the formation of the LaOF compound.

Use of lithium ion batteries is currently the method of choice when it comes to local stationary storage of electrical energy. In the search for an alternative system, fluoride ion batteries (FIBs) emerge as a candidate due to their high theoretical capacity, and no lithium is needed for its operation. To improve the cycling performance and lower the working temperature of a solid-state battery, one of the critical components is the electrolyte, which needs advanced performance. This paper aims at developing an electrolyte with enhanced ionic conductivity for fluoride ions, to be used in a FIB. Tysonite LaBaF (0 ≤ x ≤ 0.15) solid solutions were synthesized by a facile wet chemical method, and its ionic conductivity was analyzed using electrochemical impedance spectroscopy. A composition study shows that the conductivity reaches a maximum of 1.26 × 10 S·cm at 60 °C for the LaBaF pellet sintered at 800 °C for 20 h, which is 1 order of magnitude higher than that for the as-prepared pellet and 2 times higher than the conductivity of sintered ball-milled batches. The reason for this dramatic increment is the more efficient decrement of grain boundary resistance upon sintering. Morphological, chemical, and structural characterizations of solid electrolytes were studied by X-ray diffraction, scanning electron microscopy , energy dispersive X-ray spectroscopy, physisorption by the Brunauer-Emmett-Teller method, and transmission electron microscopy. Electrochemical testing was carried out for the FIB cell using LaBaF as electrolyte due to its highest conductivity among the compositions, Ce as anode, and BiF as a cathode. The cycling performance was found to be considerably improved when compared to our earlier work, which used the ball-milled electrolyte.

Metal trihalide perovskites are rapidly redefining the landscape of solid-state semiconductors utilized as active medium in photovoltaics and in light generation. Within this materials space, organic-inorganic hybrid formamidinium lead bromide (FAPbBr3) has arisen as a promising candidate for efferent light emitting devices, due to its capacity for sharp and bright green light emissions (530 nm). Herein we have applied a facile single-step ligand-mediated method for phasecontrolled synthesis of FAPbBr3 cube-and rod-shaped nanocrystals (NCs), starting from different ratios of precursor agents. Examining their structural and optoelectronic properties-using a combination of synchrotron X-ray diffraction, X-ray spectroscopy, scanning electron microscopy and steady-state and time-resolved photoluminescence (PL)-we reveal the two NC types to fundamentally differ. While the cube-shaped NCs exhibit properties aligning with that of bulk FAPbBr3, the nanorods exhibit a two-phase microstructure and the coexistence of both a typical cubic perovskite structure alongside the formation of a new low-symmetry monoclinic phase (P2/m). Further, the two-phase nanorods display a bright dual PL emission (peaks centered near 490 nm and 530 nm) and complex luminescence dynamics, properties characteristic of quasi-2D perovskites. The two phase nanorods generation can be assigned to the proton exchange in the presence of excess of FA + during the synthesis.

Semiconducting nanomaterials have been widely explored in diverse optoelectronic applications. Colloidal lead halide perovskite nanocrystals (NCs) have recently been an excellent addition to the field of nanomaterials, promising an enticing...

Lead halide perovskites are promising candidates for high-performance light-emitting diodes (LEDs); however, their applicability is limited by their structural instability toward moisture. Although a deliberate addition of water to the precursor solution has recently been shown to improve the crystallinity and optical properties of perovskites, the corresponding thin films still do not exhibit a near-unity quantum yield. Herein, we report that the direct addition of a minute amount of water to post-treated formamidinium lead bromide (FAPbBr3) nanocrystals (NCs) substantially enhances the stability while achieving a 95% photoluminescence quantum yield in a NC thin film. We unveil the mechanism of how moisture assists in the formation of an additional NH4Br component. Alongside, we demonstrate the crucial role of moisture in assisting localized etching of the perovskite crystal, facilitating the partial incorporation of NH4 +, which is key for improved performance under ambient conditions. Finally, as a proof-of-concept, the application of post-treated and water-treated perovskites is tested in LEDs, with the latter exhibiting a superior performance, offering opportunities toward commercial application in moisture-stable optoelectronics.

5‐Hydroxyindoles are privileged structures that form part of various bioactive compounds. The Nenitzescu reaction of quinones and enamines is one of the most powerful methods to obtain 5‐hydroxyindoles. In this work, we have applied the Nenitzescu reaction to 2‐(2‐chloropyrid‐3‐yl)benzoquinones. Mixtures of regioisomers were obtained that could be separated in the 4‐ and 6‐substituted analogues, and then cyclized separately in a metal‐free base‐catalyzed reaction, affording novel tetracyclic indole derivatives. These are indeed the first examples reported in the literature of the linear pyrido[3′,2′ : 4,5]furo[3,2‐b]indole and angular 1H‐pyrido[2′,3′ : 4,5]furo[2,3‐c]indole systems. The regioselectivity and the yield of the Nenitzescu reaction were found to be dependent on the N‐substituent at the enamine. Furthermore, we analyzed the UV‐Vis and PL spectra of the new systems, and this was supported by DFT calculations, allowing us to compare the properties of angular compared to linearly shaped compounds.

In the present work, Cerium Fluoride (CeF3) was selected as the host material because of its High density, fast response and high radiation resistance, efficient absorption and energy transfer by host (to activator). Rare earths have been used to show the process of Quantum Cutting (QC) via energy transfer process between Tb3+ and Yb3+ incorporated in CeF3. For the synthesis of CeF3 nanoparticles codoped with Tb3+ and Yb3+ ion, co-precipitation route was employed. Different doping concentrations were prepared to study the changes that take place in the luminescence spectra of the composition. Thus, concentration dependent study of the fluorescence of CeF3: Tb3+, Yb3+ was carried out. These materials have great applications in solar cell devices as quantum efficiencies up to 200 % can be achieved.

The addition of potassium thiocyanate (KSCN) to the FAPbBr 3 structure and subsequent post-treatment of nanocrystals (NCs) lead to high quantum confinement, resulting in a photoluminescent quantum yield (PLQY) approaching unity and microsecond decay times. This synergistic approach demonstrated exceptional stability under humid conditions, retaining 70% of the PLQY for over a month, while the untreated NCs degrade within 24 h. Additionally, the devices incorporating the post-treated NCs displayed 1.5% external quantum efficiency (EQE), a 5-fold improvement over untreated devices. These results provide promising opportunities for the use of perovskites in moisturestable optoelectronics.