Halogen Composition Research Articles

Dynamic exciton-to-dopant energy transfer tuning of Mn2+-Doped perovskite nanocrystals by PBG effect

Cesium lead halide perovskite nanocrystals (CsPbX3 NCs) doped with Mn2+ brings attractive long-wavelength emission and flexible color tunability. However, modulating the exciton-to-Mn2+ energy transfer efficiency poses a challenge, particularly when relying on traditional methods such as changing halogen composition or incorporating external cations, which often complicate the process. In this work, a simple photonic bandgap (PBG)-modulation strategy is applied to modulate the exciton-to-Mn2+ energy transfer by constructing a sandwich “PC-Perovskite-PC” structure with two photonic crystal (PC) films and Mn2+ doped CsPb(ClBr)3 NPs. When the PBG and the host emission band change from deviation to coincidence, the lifetime of Mn2+ decreases from 0.54 ms to 0.36 ms owing to the enhancing energy transfer efficiency by PBG effect. Meanwhile, the ratios of orange and blue emissions (O/B) increase from 1.36 to 1.6. In addition, the back energy transfer also can be modulated. When the PBG matches well with the Mn2+ emission band, the lifetime of the host emission exhibits the largest value (1.25 ns) owing to back energy transfer from Mn2+ the host. Meanwhile, the O/B value shows the smallest value (0.52) attributed to the decreased spontaneous radiation of Mn2+ and the enhanced host emission. When PBG deviates from the Mn2+ emission band, the lifetime of the host emission decreases but O/B value increases gradually. This work provides new strategy for the modulation of energy transfer in Mn2+ doped CsPb(ClBr)3 NPs.

Heavy halogen compositions of peridotite massifs in the Ivrea-Verbano Zone and implications for strong modification of mantle rocks

The lithospheric mantle affected by metasomatism is an important reservoir for halogens and often preserves significant heterogeneity in halogen abundances. However, the halogen compositions of the non-metasomatized mantle rocks with depleted geochemical features have not been well studied, impeding a comprehensive understanding of the halogen distribution in the mantle. The Balmuccia (BM) and Baldissero (BD) peridotite massifs in the Ivrea-Verbano Zone, Italian Alps, represent fragments of the sub-continental lithospheric mantle (SCLM) that are fresh and devoid of subduction-related mantle metasomatism. Here we examine the heavy halogen contents of well-characterized spinel-facies mantle peridotites (n = 20) and pyroxenites (n = 16) from the BM and BD massifs. The results indicate significant variation in whole rock halogen contents of peridotites and pyroxenites, with chlorine (Cl) ranging from <30 to 244 μg/g, bromine (Br) from <0.10 to 0.94 μg/g, and iodine (I) from <0.015 to 0.12 μg/g. Some peridotites and pyroxenites show rather low halogen contents (below the detection limit), consistent with their depleted features. However, a large number of samples display halogen contents far higher than the depleted MORB mantle (i.e., Cl: 3–10 μg/g) and peridotite xenoliths from the strongly metasomatized mantle, although ∼30 % of the halogens were leached out by ultrapure water or dilute nitric acid. The data suggest variable halogen enrichment in many mantle rocks. The halogen contents of different types of mantle rocks do not vary with major elements and incompatible trace elements (e.g., Nb), indicating that halogen compositions are not controlled by magmatic processes such as melting and melt-peridotite reaction. Instead, secondary fluid inclusions are abundant and mainly distributed as trails within olivine and pyroxene in both peridotites and pyroxenites, which were likely trapped during the exhumation of these mantle rocks. Their elevated halogen/Nb ratios compared with MORB mantle and strong correlations with Ba/Nb support the effect of fluids. Micro-Raman analyses identify hydrous serpentines within fluid inclusions. Moreover, mass balance calculation indicates that halogen enrichment is mainly caused by secondary fluids (> 90 %). Together, our findings highlight that the fluid percolation in the mantle rocks during exhumation can intensely modify the halogens, to a similar degree as mantle metasomatism, suggesting the sensitivity of halogens to secondary modification.

Control of magmatic halogen composition and redox state on the zonation of metal mineralization across active continental margins: Perspectives from the world-class South China metallogenic province

Active continental margins are the major sites of continental magmatism and associated hydrothermal ore deposits with a broad metal spectrum. Mineralization across active continental margins typically displays spatial zonation, with porphyry copper-(molybdenum‑gold) deposits in volcanic arcs and tin- and tungsten-dominated mineralization occurring further inland in a back-arc setting. Particularly, tin and tungsten commonly form separate deposits in back-arc regions, even though both metals exhibit similar lithophile behavior. The key factors governing this metallogenic zonation remain unclear. The world-class South China metallogenic province hosts over 50 % of the global tungsten resources, along with a significant amount of tin and copper resources distributed in different mineralization belts, making it an ideal location in which to study regional metal zonation. Here, we comprehensively integrate a very large dataset of the halogen volatile composition (F, Cl) and oxygen fugacity of granites related to tin, tungsten, and copper mineralization in the South China continental margin. Our compilation, derived from a substantial collection of zircon, apatite, mica, and whole-rock geochemistry data, suggests that lateral variations in granite magmatism (away from the trench), transitioning from chlorine-rich and oxic to fluorine-rich and reduced conditions, exert the primary control on copper versus tin‑tungsten mineralization in the arc and back-arc regions, respectively. Differences in oxygen fugacity have a minor impact on the decoupling of tin and tungsten mineralization despite tin granites being universally reduced (ΔFMQ = −1.8 to −0.1, where FMQ is the fayalite-magnetite-quartz redox buffer) and tungsten granites having a broader redox range (ΔFMQ = −1.5 to +1.2). Instead, the disparity in fluorine content plays a more crucial role in controlling the spatial separation of tin and tungsten mineralization observed in the back-arc setting. Nd-Hf and He-Ar isotopic modeling calculations suggest that magmas linked to tin mineralization have a more pronounced involvement of F-rich mantle components compared to those associated with tungsten. Elevated fluorine (ca. 650–8000 ppm) in tin-associated magmas allowed an extreme degree of magmatic differentiation and delayed fluid exsolution due to high H2O solubility in F-rich silicate melts, ensuring Sn enrichment in highly evolved melts. In contrast, early fluid exsolution under less F-rich conditions (ca. 100–700 ppm) led to early tin loss from the melts, ultimately resulting in tungsten-dominant mineralization. This work emphasizes the combined influence of halogen composition and redox state on the regional mineralization zonation in world-class metallogenic provinces, providing vectors for global metal exploration in both past and currently active continental margins.

Effects of halogens and alkali metals on guanidinium-ethylammonium hybrid-doped perovskite photovoltaic devices

Effects of substitution of halogen anions and addition of alkali metal cations for guanidinium (GA)-ethylammonium (EA) hybrid-doped perovskite solar cells were investigated by fabricating devices and comparing their photovoltaic properties. The halogen compositions of the additives were found to contribute to the improvement of preferred orientations of perovskite crystals, and the order of the effectiveness was I, Cl, and Br. In addition, the addition of alkali metal cations contributed to improvement of the conversion efficiencies, and 3 % addition of cesium at the CH3NH3 site was the most effective. It was also found that the short-circuit current densities and fill factors depended on the (100) preferred crystal orientation of the perovskite compounds.

Size and Polarizability of Boron Cluster Carriers Modulate Chaotropic Membrane Transport

AbstractPerhalogenated closo‐borates represent a new class of membrane carriers. They owe this activity to their chaotropicity, which enables the transport of hydrophilic molecules across model membranes and into living cells. The transport efficiency of this new class of cluster carriers depends on a careful balance between their affinity to membranes and cargo, which varies with chaotropicity. However, the structure–activity parameters that define chaotropic transport remain to be elucidated. Here, we have studied the modulation of chaotropic transport by decoupling the halogen composition from the boron core size. The binding affinity between perhalogenated decaborate and dodecaborate clusters carriers was quantified with different hydrophilic model cargos, namely a neutral and a cationic peptide, phalloidin and (KLAKLAK)2. The transport efficiency, membrane‐lytic properties, and cellular toxicity, as obtained from different vesicle and cell assays, increased with the size and polarizability of the clusters. These results validate the chaotropic effect as the driving force behind the membrane transport propensity of boron clusters. This work advances our understanding of the structural features of boron cluster carriers and establishes the first set of rational design principles for chaotropic membrane transporters.

Size and Polarizability of Boron Cluster Carriers Modulate Chaotropic Membrane Transport.

Perhalogenated closo-borates represent a new class of membrane carriers. They owe this activity to their chaotropicity, which enables the transport of hydrophilic molecules across model membranes and into living cells. The transport efficiency of this new class of cluster carriers depends on a careful balance between their affinity to membranes and cargo, which varies with chaotropicity. However, the structure-activity parameters that define chaotropic transport remain to be elucidated. Here, we have studied the modulation of chaotropic transport by decoupling the halogen composition from the boron core size. The binding affinity between perhalogenated decaborate and dodecaborate clusters carriers was quantified with different hydrophilic model cargos, namely a neutral and a cationic peptide, phalloidin and (KLAKLAK)2. The transport efficiency, membrane-lytic properties, and cellular toxicity, as obtained from different vesicle and cell assays, increased with the size and polarizability of the clusters. These results validate the chaotropic effect as the driving force behind the membrane transport propensity of boron clusters. This work advances our understanding of the structural features of boron cluster carriers and establishes the first set of rational design principles for chaotropic membrane transporters.

Tunability of Photovoltaic Functions via Halogen Substitution [(Ade)2 CdX4](X = Cl, Br): A Class of Three-Dimensional Organic-Inorganic Hybrid Materials.

Two new three-dimensional organic-inorganic hybrid crystalline materials, [(Ade)2 CdCl4] (1) and [(Ade)2 CdBr4] (2), were obtained by the slow evaporation of adenine (Ade) and cadmium chloride in aqueous solution at room temperature with hydrochloric acid and hydrobromic acid used as halogen sources. The structural, thermal, optical, and electrical properties were characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, variable-temperature-variable-frequency dielectric constant analysis, and electrochemical tests. With increasing the substitution of Cl by Br, the composition of the material changed and the space group shifted from P-1 to P21/m, with a significant blue-shift in the fluorescence emission. Changing the temperature induced the deformation of the three-dimensional framework structure formed by hydrogen bonding interactions, leading to dielectric anomalies. Cyclic voltammetry tests showed the good reversibility of the electrolysis process. The structural diversity of the complexes was realized by modulating the halogen composition, and a new method for designing novel organic-inorganic hybrids with controllable photoelectric functionality was proposed.

Precise structure-tailoring of multicomponent nanocatalysts enabled by continuous flow-controlled flash nanoprecipitation technique

Nanostructured catalysts with diverse compositions offer an exciting prospect for various catalytic applications. The precise control of nanostructures allows to tune the physicochemical properties of nanocatalysts and improve their performance. However, most preparative methods rely on conventional batch systems, which require tedious procedures and cause low productivity. Herein, we reported a novel engineered flash nanoprecipitation (FNP) technique to synthesize well-structured nanocatalysts in a continuous-flow procedure with intelligent operation and high productivity, in which a series of multicomponent bismuth oxyhalides (BiOClxBr1-x) were demonstrated as the model catalysts. This method was established on the uninterrupted continuous synthesis of BiOClxBr1-x with precisely controlled microstructure by simply altering the flow rate ratio of precursor fluids in the reactor. The computational fluid dynamics (CFD) simulation showed that the automized flow setup could achieve the accurate control over the intensified fluid mixing. Significantly, a volcano relationship between the halogen compositions and catalytic activities toward photodegradation of tetracycline (TC) was observed, which indicated that the structural changes enabled band structure-dependent regulation. The FNP-processed BiOCl0.75Br0.25 possessed a balanced redox ability and light absorption, thus located at the peak of volcano with a five-fold enhancement of intrinsic photocatalytic activity. Overall, this work provides a promising prospect of continuous-flow technique in the engineered manufacturing of the advanced nanomaterials, offering fine-tuning of the nanostructures of materials with low cost and high productivity.

Hot-Injection Synthesis of Cesium Lead Halide Perovskite Nanowires with Tunable Optical Properties.

Metal halide perovskite semiconductors have emerged as promising materials for various optoelectronic applications due to their unique crystal structure and outstanding properties. Among different forms, perovskite nanowires (NWs) offer distinct advantages, including a high aspect ratio, superior crystallinity, excellent light absorption, and carrier transport properties, as well as unique anisotropic luminescence properties. Understanding the formation mechanism and structure-property relationship of perovskite NWs is crucial for exploring their potential in optoelectronic devices. In this study, we successfully synthesized all-inorganic halide perovskite NWs with high aspect ratios and an orthorhombic crystal phase using the hot-injection method with controlled reaction conditions and surface ligands. These NWs exhibit excellent optical and electrical properties. Moreover, precise control over the halogen composition through a simple anion exchange process enables the tuning of the bandgap, leading to fluorescence emission, covering a wide range of colors across the visible spectrum. Consequently, these perovskite NWs hold great potential for efficient energy conversion and catalytic applications in photoelectrocatalysis.

One‐Step Fabrication of New PCPNs with Unique Optical Responses for Ultra‐Stable Anti‐Counterfeiting Labels

AbstractConstructing a library of stable phosphors with unconventional fluorescence (FL) and room temperature phosphorescence (RTP) color combination is an effective approach to enhance anti‐counterfeiting strength, but remains a challenge. Herein, a one‐step strategy is proposed to fabricate ultra‐stable CsPbX3/carbon dots (CDs) @NH4AlP2O7 (X = Cl, Br, and I) nanocomposites (PCPNs) with full‐spectrum FL emission and constant short‐wavelength blue RTP emission, breaking the conventional luminescent properties that RTP generally exhibit obvious wavelength red‐shifts compared with FL. The enhanced full‐color (457–612 nm) FL emissions are implemented by adjusting halogen compositions, which is attributed to CsPbX3 as the dominant FL center. Owing to the RTP emission of CDs, constant long‐lived blue RTP emission lasting 12 s is observed from PCPNs. Additionally, the PCPNs exhibit remarkable tolerance to prolonged ultraviolet irradiation and erosion by solutions with various pH and solvents, supported by NH4AlP2O7 inert shell stabilizing the perovskite structure and triplet state. When the anti‐counterfeiting ink based on PCPNs is printed on various substrates, fine anti‐counterfeiting labels with unconventional emission combinations of FL and RTP are formed and show excellent solvent resistance and mechanical stability. This study provides fresh perspectives on the development of anti‐counterfeiting labels with enhanced security strength and long‐term effects.

The Tunable Electronic and Optical Properties of Two-Dimensional Bismuth Oxyhalides.

Two-dimensional (2D) bismuth oxyhalides (BiOX) have attracted much attention as potential optoelectronic materials. To explore their application diversity, we herewith systematically investigate the tunable properties of 2D BiOX using first-principles calculations. Their electronic and optical properties can be modulated by changing the number of monolayers, applying strain, and/or varying the halogen composition. The band gap shrinks monotonically and approaches the bulk value, the optical absorption coefficient increases, and the absorption spectrum redshifts as the layer number of 2D BiOX increases. The carrier transport property can be improved by applying tensile strain, and the ability of photocatalytic hydrogen evolution can be obtained by applying compressive strain. General strain engineering will be effective in linearly tuning the band gap of BiOX in a wide strain range. Strain, together with halogen composition variation, can tune the optical absorption spectrum to be on demand in the range from visible to ultraviolet. This suggests that 2D BiOX materials can potentially serve as tunable novel photodetectors, can be used to improve clean energy techniques, and have potential in the field of flexible optoelectronics.

Apatite evidence for a fluid-saturated, crystal-rich magma reservoir forming the Quellaveco porphyry copper deposit (Southern Peru)

Large volume, intermediate-felsic magma reservoirs are the source of melt and mineralising fluids which generate porphyry copper deposits. Cooling and crystallisation of hydrous magmas drives the exsolution and expulsion of a magmatic volatile phase—a process which remains challenging to constrain in porphyry Cu systems where the record of magma volatile compositions is rarely preserved. Here, we use the halogen compositions of apatite inclusions shielded as inclusions within zircon to constrain volatile evolution in magma reservoirs which pre-date and are synchronous with porphyry Cu mineralisation at Quellaveco, Southern Peru. Geochemical and textural data confirm that the zircon-included apatites escaped re-equilibration with hydrothermal fluids, unlike apatites found in the groundmass of the same rocks. We, therefore, recommend that future studies attempting to reconcile magmatic volatile budgets using apatite in porphyry Cu systems should focus on apatite inclusions in zircon. By combining the apatite inclusion data with numerical modelling, we find evidence that the magma reservoir sourcing porphyry Cu mineralisation remained fluid-saturated for the entire period recorded by apatite crystallisation. By contrast, the pre-mineralisation batholith shows more variable, potentially fluid-undersaturated behaviour. Our modelling suggests that in order to attain the porphyry melt volatile compositions inferred from apatite, the magma reservoir must have exsolved a large proportion of its volatile budget, consistent with having been held at high crystallinity (40–60% crystals). This crystallisation interval coincides with peak chlorine and copper extraction from intermediate-felsic magmas, and would have permitted efficient fluid migration and accumulation at the roof of the system. We suggest that the storage of large-volume, long-lived, crystal-rich magma reservoirs in magmatic arcs may be a critical step in generating world-class porphyry copper deposits.

Guanidium iodide treatment of size-controlled CsPbI3 quantum dots for stable crystal phase and highly efficient red LEDs

The optoelectronic properties of lead-halide perovskite quantum dots (QDs) can be tuned according to their halogen composition ratio and quantum size effect. However, the pure red emission of CsPbI3 QDs exhibits poor phase stability, thereby resulting in a phase transition to a nonphotoactive yellow phase at room temperature. These phase instabilities are accompanied by crystal strain and instability of the QD surface, which induce ion diffusion and desorption. Herein, we demonstrate the precise size control and postsynthetic guanidinium iodide (GAI) treatment to stabilize the crystal phase of CsPbI3 QDs. These synergistic effect results in higher ambient photoluminescence stability and photostability than those of pristine QDs. More importantly, the CsPbI3 QD light-emitting diodes achieve excellent external quantum efficiency of 22.5% and longer operational stability of over 10 h by the synergy effect of QD size control and GAI treatment.

Photo- and Thermal-Induced Ion Migration and Phase Separation in Mn-Doped Two-Dimensional PEA2PbX4 Perovskite.

Ion migration and phase separation in perovskite materials have negatively affected the solid-state lighting and display. Studying photo- and thermal-induced degradation is considered as a promising approach to understanding the luminescence mechanism and promoting practical applications. Herein, the Mn-doped two-dimensional PEA2PbX4 (X = Cl, Br, I) microcrystals with changing halogen composition were synthesized by an acid-assisted post-processing strategy. Then, photo- and thermal-induced degradation was studied by using steady-state and time-resolved photoluminescence (PL) spectroscopy. The band edge exciton PL peak of Mn-doped 2D PEA2PbX4 microcrystals was adjusted from 397 to 500 nm. The reduced Mn PL lifetime (1.37 to 0.21 ms) was monitored under ion exchange from Cl to Br to I. The degradation mechanism could be divided into two cases: (i) The halide ion migration in Mn-doped 2D perovskite under continuous illumination was revealed, suggesting that the migration of Cl ions was more accessible than that of Br and I. (ii) The PL redshift and lifetime reduction were observed after annealing at 420 K, which means that thermally induced aggregation of Mn ions resulted in the formation of Mn2+-Mn2+ dimers. In addition, the experimental results indicated that the induced B-site phase separation at high temperature annealing made the mixed perovskite phase of Pb and Mn ultimately transform into pure PEA2PbBr4 and PEA2MnBr4.

Apatite chemistry in shoshonitic magmas: Insights into the volatile evolution at La Fossa volcano (Vulcano Island, Aeolian Arc, Italy)

Apatite, which has demonstrated to be useful for tracking volatile evolution in magmatic systems, is a common accessory in La Fossa active volcano (Vulcano island, Italy) products. We performed in situ geochemical (major and trace elements, Cl, F, S) analyses on apatite of La Fossa, and used the data to track the pre-eruptive magmatic volatile evolution for the La Fossa shoshonitic suite, to provide insights on magma evolution in the plumbing system and to investigate volatile fluxing. Our results confirm that apatite volatile chemistry is a valuable tool to give constraints on pre-eruptive volatile contents of magmas. For specific compositions, however, we obtained an underestimation of the water contents with respect to those estimated with plagioclase-liquid hygrometer in previous works. Vulcano apatite halogen composition also indicates that water saturation and pre-eruptive exsolution of a hypersaline aqueous fluid phase occurred when the magma reached rhyolitic composition. The high As, Bi and Cd contents found in apatite crystals belonging to shoshonite and high-K trachyte suggest that the magma reservoirs feeding these eruptions were affected by a deep volatile fluxing which was able to carry these trace elements up to shallow levels. This is in agreement with the occurrence of the deep degassing already demonstrated at La Fossa volcano on the basis of petrological and geochemical data, and supports the apatite geochemical approach to track deep volatile fluxing.

Unusual isostructural Br/I substitution effect on the crystal structure and optical properties of hybrid halobismuthates

The gradual change of the optical properties of solid solutions by variation of the halogen composition is shown.

Heavy halogen compositions of lamprophyres derived from metasomatized lithospheric mantle beneath eastern North China Craton

Abstract Halogens and other volatiles are widely recycled into the deep mantle by subduction and are key components to metasomatize the sub-continental lithospheric mantle (SCLM). Lamprophyres are well known to be rich in volatiles and are important for understanding the halogen characteristics of the meta-somatized SCLM and/or the mobilization of halogens during the ascent of such volatile-rich, low-degree partial melts. The North China Craton (NCC) hosts lamprophyre dikes coeval with extensive thinning of the eastern NCC in the Mesozoic and generated from lithosphere metasomatized by multiple-stage subduction components. Here we report bulk-rock heavy halogens (Cl, Br, and I) of 16 lamprophyres from the eastern NCC. The bulk-rock halogen concentrations are overall very low (Cl = 58–170 μg/g, Br = 285–559 ng/g, and I &amp;lt;5 ng/g), comparable with depleted Mid-Ocean ridge basalts (N-MORBs). Volatile-rich minerals (e.g., amphibole and biotite) are abundant (20–30 vol%) in these lamprophyres, however, electron probe microanalyses (EPMA) data indicate that amphiboles are mainly rich in OH and F but display very low Cl concentrations (0.01–0.04 wt%). The bulk rock and amphibole data consistently indicate low abundances of heavy halogens in the lamprophyres, which is difficult to reconcile with the remarkable enrichment of fluid-mobile large ion lithophile elements such as Ba, Rb, and K. Based on low Cl/Nb and Br/Nb but high Ba/Nb and K/Nb ratios, the low halogen concentrations likely resulted from extensive volatile loss (&amp;gt;90%) during melt ascent. The low Cl concentrations in early-stage amphiboles (Mg# 60–64) further indicate that such loss would have occurred before amphibole crystallization at a depth of ~15 km. We thus propose that crystallization of early olivines and pyroxenes and reaction with surrounding mantle rocks likely induced volatile saturation and exsolution, leading to strong partitioning of the halogens into the exsolved aqueous volatile phases and thus the extensive loss of halogens from the rising melt. These results reveal that significant volatile loss of halogens not only occurs during surficial low-pressure eruption but also at much deeper levels in the crust, as also identified for some kimberlites. Consequently, it would be difficult to constrain the primitive halogen components of the mantle sources via lamprophyres or similar magmas.

(Invited, Digital Presentation) Surface Engineering of Fluorescent CsPbBr3 and Carbon Quantum Dots By Perfluorocarboxylic Acid

CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) are an extremely attractive material with a narrow fluorescence peak and tunable emission color by halogen composition. Surface ligands have a variety of effects, including control of size and shape, uniform dispersion through good affinity with solvents and matrices, elimination of quenching sites due to surface defect capping effects and subsequent improvement of luminescent properties, and improvement of stability through surface protection. CsPbX3 QDs can be synthesized by hot injection and room temperature precipitation methods, using oleic acid (OA) and oleylamine (OLA) as surface ligands. One of the problems with these QDs is their low stability; the mechanism of degradation of QDs is the easy proton transfer between the carboxylate groups of OA and the ammonium groups of OLA on the surface of the QDs, resulting in the desorption of OA and OLA from the QD surface. Ligand desorption creates halogen vacancies, which act as trap levels that cause nonradiative recombination; therefore, it is important to design ligands that hardly desorb from the QD surface to suppress degradation of the QDs. In this talk, we will introduce our results on surface ligand of perfluorocarboxylic acid that improves thermal stability of CsPbBr3 QDs [1].Fluorescent carbon quantum dots (CQDs) are attracting attention as an alternative material to toxic QDs. In order to synthesize CQDs with a variety of fluorescent colors, it is effective to select aromatic compounds as carbon sources. The fluorescence color of CQDs changes depending on the polarity of the dispersant. This fluorescence solvatochromism is attributed to the change in the HOMO-LUMO energy gap of CQDs through the dipolar and hydrogen bonding interactions between CQDs and the dispersant molecules. In this talk, we will show that fluorescence solvatochromism of CQDs synthesized from p-phenylenediamine can be modulated by surface modification with perfluorocarboxylic acid [2].[1] D. Sato, Y. Iso, T. Isobe, ACS Omega, 5, 1178-1187 (2020).[2] K. Sato, R. Sato, Y. Iso, T. Isobe, Chem. Commun., 56, 2174-2177 (2020).

How Halide Sub-Lattice Affects Li Ion Transport in Antiperovskites

Li-based antiperovskites (LiAP, Li3-x OH x X, X = Cl, Br) are an emergent class of Li-ion conductors that are potential candidates for electrolytes in all-solid-state batteries. As a material class, pLiAP shows vast compositional design freedom; however, the resulting properties are susceptible to synthesis and processing methodologies. For example, proton incorporation and halide mixing stabilize the perovskite cubic phase near room temperature, and halides mixtures near the eutectic points drive the solid-state reaction temperature down, allowing for faster synthesis and processing conditions (< 1 h). The mixed halogen compositions, such as Li2OHCl0.37Br0.63, also show a 30-fold improvement in room temperature ionic conductivity of a single halide structure, 1.5 x 10-6 vs. 4.9 x 10-8 S cm-1 (Li2OHCl). Despite the growing interest in these materials, important questions remain about LiAPs on the structure-property correlation upon halide substitution and the correlations between the OH/halide dynamics and the Li-ion transport. We thus attempted to deconvolute how proton dynamics and halide substitution enhance or impede ionic conduction in pLiAP at compositions near the halide salts' eutectic points.We combined infrared spectroscopy and nuclear magnetic resonance (NMR) with first-principles density functional theory (DFT) calculations to deconvolute halide mixing effects from local proton dynamics on Li-ion transport. The NMR results and ab initio molecular dynamics suggest that Li+ transport is more strongly correlated with halide dynamics. While the hydroxide does stabilize the highly conductive cubic structure, it limits correlative ionic transport and thus lowers Li+ conductivity.Experiment design, data analysis, and manuscript preparation (RLS) were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering. Synthesis (THB and JN) were supported by Asst. Secretary, Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program. P. J. acknowledges partial support by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-96ER45579. H. F. was supported from U.S. Department of Energy (Award No. DE-EE0008865). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The NMR characterization part of the work is supported by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, and Basic Energy Sciences. The NMR work was performed at the W. R. Wiley Environmental Molecular Sciences Laboratory, a DOE User Facility sponsored by the Office of Biological and Environmental Research, located at Pacific Northwest National Laboratory. Figure 1

Scalable synthesis of efficiently luminescent and color-tunable CsPbX3 (X=Cl, Br, I) nanocrystals by regulating the reaction parameters

All-inorganic CsPbX3 (X=Cl, Br, I) perovskite nanocrystals (NCs) exhibit attractive optoelectronic properties for lighting and displays application but suffer from the lack of profound insights into their reaction kinetics. Herein, a modified ligand-assisted reprecipitation (LARP) method was developed to synthesize high-quality CsPbBr3 NCs by utilizing oleic acid (OA) and n-octylamine (OTAm) as surface ligands, and the effect of Cs/Pb ratio, precursors and ligands concentration on the structure, morphology and fluorescence properties was systematically investigated. The monodisperse CsPbBr3 NCs with cubic shape and average particle size of 13.7 nm are obtained by optimizing the reaction parameters. Appropriately increasing the Cs/Pb ratio and precursors concentration to 0.5 and 1.0 mM are favorable for forming a more complete crystal structure with lower defect states density, which can significantly enhance the PL intensity. Notably, the surface defect states of CsPbBr3 NCs are effectively passivated by the coordinated OA and OTAm ligands, and the maximum photoluminescence quantum yield (PLQY) can reach to 85.2%. Importantly, the effective synthesis of high-quality CsPbBr3 NCs can be amplified up to 50 times of reaction volume after finely optimizing the reaction parameters. Based on a facile anion exchange process, the CsPbX3 NCs with variable halogen composition exhibit tunable emission of 443.3∼649.1 nm and a wide color gamut of 117% NTSC standard. This work provides profound sights on the reaction kinetics of perovskite NCs, and further promotes its practical application in optoelectronic field.