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ZnTPY-chelated PbI2 nuclei effectively reduce the activation energy of perovskite crystallization resulting in higher conversion of PbI2 into uniform perovskite crystalline films, which ultimately improves the performance of perovskite solar cells.

The device efficiency of

Mixed-cation hybrid perovskite nanocrystal (HPNC) with high crystallinity, color purity, and tunable optical band gap offers a practical pathway toward next-generation displays. Herein, we present a two-step modified hot-injection combined with cation compositional engineering and surface treatment to synthesize high-purity Cs

Prion protein is composed of a structure-unsolved N-terminal domain and a globular C-terminal domain. Under limited trypsin digestion, mouse recombinant prion protein can be cleaved into two parts at residue Lys105. Here, we termed these two fragments as the N-domain (sequence 23-105) and the C-domain (sequence 106-230). In this study, the structural properties of the N-domain, the C-domain, and the full-length protein were explored using small-angle X-ray scattering, analytical ultracentrifugation, circular dichroism spectroscopy, and the 8-anilino-1-naphthalenesulfonic acid binding assay. The conformation and size of the prion protein were found to change sensitively under the solvent conditions. The positive residues in the sequence 23-99 of the N-domain were found to be responsible for the enhanced flexibility with the salt concentration reduced below 5 mM. The C-domain containing a hydrophobic patch tends to unfold and aggregate during a salt-induced structural collapse. The N-domain collapsed together with the C-domain at pH 5.2, whereas it collapsed independently at pH 4.2. The positively charged cluster (sequence 100-105) in the N-domain contributed to protecting the exposed hydrophobic surface of the C-domain.

Site-selectively chemical bioconjugation of peptides and proteins can improve the therapeutic exploration of modified protein drugs. Only 3.8% natural abundance of phenylalanine in protein and nearly 90% of proteins contain at least one phenylalanine residue in their sequenced, showing the potential in biopharmaceutical utility of the phenylalanine bioconjugation. However, the covalent bioconjugation of native phenylalanine is one of the most challenging problems in protein modification. Herein, an approach to protein modification is described that relies on a photoredox method for the site-selective bioconjugation of phenylalanine. This methodology has been validated on peptides as well as protein insulin using a straightforward and mild condition. In addition, based on characterization by near-UV CD spectroscopy and small angle X-ray scattering (SAXS), this pyrazole labeling approach permitted the insulin hexamer to completely dissociate into the monomeric form, thus making it a potential candidate for use as rapid-acting insulin for the treatment of diabetes.

Chitosan is a naturally derived biodegradable polymer with abundancy, sustainability, and ease of chemical modification. Polyurethanes are a family of elastic biocompatible polymers, and composites of polyurethanes have versatile properties and applications. Chitosan-polyurethane composites were recently developed but had insufficient strength and limited stretchability. In the current study, cellulose nanofibers (CNFs) were integrated in chitosan-polyurethane composites to prepare stretchable and anisotropic materials. A biodegradable polyurethane was first synthesized, end-capped with aldehyde to become dialdehyde polyurethane (DP) nanoparticles, and added with CNFs to prepare the DP-CNF composite crosslinker (DPF). The waterborne DPF crosslinker was then blended with chitosan solution to make polyurethane-CNF-chitosan (DPFC) composites. After blending, DPFC may form hydrogel in ~33 min at room temperature, which confirmed crosslinking. Composite films cast and dried from the blends showed good elongation (~420.2 %) at 60 °C. Anisotropic films were then generated by tension annealing with pre-strain. The annealed films with 200 % pre-strain exhibited large elastic anisotropy with ~4.9 anisotropic ratio. In situ SAXS/WAXS analyses unveiled that rearrangement and alignment of the microstructure during tension annealing accounted for the anisotropy. The anisotropic composite films had the ability to orient the growth of neural stem cells and showed the potential for biomimetic and tissue engineering applications.

There have been several studies on the catalytic activity of the hydrogen evolution reaction (HER) using ultralow loading of Pt catalysts or even Pt single atom catalysts. However, Pt single atom deposited on the surface of the carbon or metal oxide material has some drawbacks, such as high possibility of Pt desorption from the supported material in the electrolyte. Besides, from the reaction mechanism perspective, each Pt atom in this type of catalyst is too far to achieve high HER efficiency via the Tafel reaction pathway. In this work, gold nanodendrites (Au NDs) with high facet surface were chosen as the supported materials for studying the relation between the low loading amount of Pt atoms and the reaction mechanism of the HER activity. The atomic deposition of Pt atoms on the surface of Au NDs can be controlled effectively using a constant-current synthetic method. It was found that the HER electrocatalytic activity of ultralow Pt loading catalyst, with Pt atoms to total surface atoms of Au NDs (O-Pt on Au NDs) of 5.5%, could achieve high efficiency via the Tafel reaction pathway, showing a low overpotential of ∼18 mV at a current density of 10 mA cm−2 and a small Tafel slope of ∼31 mV dec−1, which is close to that of commercial Pt/C with 20 wt% Pt. As confirmed by Inductively Coupled Plasma Mass Spectrometry(ICP-MS), the Pt loading amount of O-Pt on Au NDs was ∼3.8 ± 0.2 μg cm−2 on a physical area of carbon fiber paper. The turnover frequency (TOF) of O-Pt on Au NDs was found to be 40.1 ± 2.5 H2 per s at 50 mV. This work provides a feasible approach to control the atomic deposition of Pt on a specific substrate as an active catalyst for various catalytic applications.

Rationally utilizing and developing synthetic units is of particular significance for the design of high-performance non-fullerene small-molecule acceptors (SMAs). Here, a thieno[3,2-b]pyrrole synthetic unit was employed to develop a set of SMAs (ThPy1, ThPy2, ThPy3 and ThPy4) by changing the number or the position of the pyrrole ring in the central core based on a standard SMA of IT-4Cl, compared to which the four thieno[3,2-b]pyrrole-based acceptors exhibit bathochromic absorption and upshifted frontier orbital energy level due to the strong electron-donating ability of pyrrole. As a result, the polymer solar cells (PSCs) of the four thieno[3,2-b]pyrrole-based acceptors yield higher open-circuit voltage and lower energy loss relative to those of the IT-4Cl-based device. What is more, the ThPy3-based device achieves a power conversion efficiency (PCE) (15.3%) and an outstanding fill factor (FF) (0.771) that are superior to the IT-4Cl-based device (PCE = 12.6%, FF = 0.758). The ThPy4-based device realizes the lowest energy loss and the smallest optical band gap, and the ternary PSC device based on PM6:BTP-eC9:ThPy4 exhibits a PCE of 18.43% and a FF of 0.802. Overall, this work sheds light on the great potential of thieno[3,2-b]pyrrole-based SMAs in realizing low energy loss and high PCE. Four heteroheptacene-based acceptors using thieno[3,2-b]pyrrole building block were developed for the first time, and all the four acceptors-based devices realized high performance and low energy loss. Funding Agencies|National Key Research and Development Program of China - Ministry of Science and Technology [2019YFA0705900]; Basic and Applied Research Major Programme of Guangdong Province [2019B030302007]; National Natural Science Foundation of China [91433202]; Shenzhen Technology and Innovation Commission through Shenzhen Fundamental Research Program [JCYJ20200109140801751]; Hong Kong Innovation and Technology Commission [ITC-CNERC14SC01]; Foshan-HKUST [FSUST19-CAT0202]; Hong Kong Research Grants Council (RIF project) [R6021-18]; Hong Kong Research Grants Council (CRF project) [C6023-19G]; Hong Kong Research Grants Council (GRF project) [16310019, 16310020]

The formation of helical assemblies from achiral supramacromolecules has been a highly mysterious process, but is of interest for the generation of a variety of structures and properties. Herein, novel hierarchical superhelices are developed from self-assembly of achiral dendron-jacketed block copolymers (DJBCPs). The presence of focal asymmetry in both the stereochemistry of the dendrons (donors) and interactive binding sites of the copolymer chains (acceptors) plays a pivotal role in generating a spontaneous symmetry breaking through tailored donor–acceptor matching via hydrogen bonding. The focal asymmetry, on a scale of several nanometers, propagates to helical twists of the achiral DJBCP hierarchical assemblies over hundreds of nanometers, such that the primary molecular asymmetry sequentially triggers a secondary helical conformation of the dendron-jacketed blocks, then tertiary supramolecular helical assemblies and eventually quaternary superhelices. The helical twisting power of the superhelices is tunable using the dendron grafting ratio, indicating that the magnitude of helical twisting can be quantitatively adjusted from local to entire structures.

The large non-radiative recombination is the main factor that limits state-of-the-art organic solar cells (OSCs). In this work, two novel structurally similar oligomers (named 5BDTBDD and 5BDDBDT) with D-A-D-A-D and A-D-A-D-A configuration are synthesized for high-performance ternary OSCs with low energy loss. As third components, these PM6 analogue oligomers effectively suppress the non-radiative recombination in OSCs. Although the highest occupied molecular orbital (HOMO) levels of 5BDTBDD and 5BDDBDT are higher than that of PM6, the oligomers enabled ultra-high electroluminescence quantum efficiency (EQE

Electron donors and acceptors in organic solar cells (OSCs) shall strike a favorable vertical phase separation that acceptors and donors have sufficient contact and gradient accumulation near the cathodes and anodes, respectively. Random mixing of donors/acceptors at surface will result in charge accumulation and severe recombination for low carrier-mobility organic materials. However, it is challenging to tune the vertical distribution in bulk-heterojunction films as they are usually made from a well-mixed donor/acceptor solution. Here, for the first time, it presents with solid evidence that the commonly used 1-chloronaphthalene (CN) additive can tune the donor/acceptor vertical distribution and establish the mechanism. Different from the previous understanding that ascribed the efficiency enhancement brought by CN to the improved molecular stacking/crystallization, it is revealed that the induced vertical distribution is the dominant factor leading to the significantly increased performance. Importantly, the vertical distribution tunability is effective in various hot nonfullerene OSC systems and creates more channels for the collection of dissociated carriers at corresponding organic/electrode interfaces, which contributes the high efficiency of 18.29%. This study of the material vertical distribution and its correlation with molecular stacking offers methods for additives selection and provides insights for the understanding and construction of high-performance OSCs.

For undulator hard X-ray beamlines of a wide energy range, the beam intensity control is often needed to regulate the photon flux impinging on delicate detectors. Despite the capability of state-of-the-art X-ray pixel detectors being greatly advanced recently, the frontier undulator beamlines in synchrotron facilities often carry outstanding photon fluxes that are sometimes too high for certain measurements. Here, we report a developed protocol that allows intensity attenuation of an X-ray beam in the 4-23 keV energy range with flexible attenuation factors; a prototype is installed and tested on the 13A biological small-angle X-ray scattering beamline of the 3 GeV Taiwan Photon Source (TPS) of the National Synchrotron Radiation Research Center, Hsinchu, Taiwan. The intensity attenuation system is modified from a commercially available pneumatically actuated, vacuum-type precision X-ray attenuator of ADC ABS-300; the system provides beam attenuation factors covering 8 orders of intensity attenuation for an X-ray beam in 4-23 keV. This was achieved with selected combinations of 10 sets of metal foils comprising different thicknesses of Al, Ti, Cu, and Ta foils. A user-friendly protocol is established to automatically compare a subscribed attenuation factor with all the possible attenuation factors from the 1024 combinations of the 10 sets of foils in the X-ray energy used, and determine a set of the metal foils having a best-matched attenuation factor. Calculation of beam intensity attenuations with the selected foils is coded with Python and integrated into the Experimental Physics and Industrial Control System (EPICS). The input of an attenuation factor is done through a graphical display of the attenuator system based on the Control System Studio (CSS). The developed X-ray beam attenuation system provides a convenient and intuitive beam intensity control and has the potential to be adopted in future beamlines.

Rationally utilizing and developing synthetic units is of particular significance for the design of high-performance non-fullerene small-molecule acceptors (SMAs). Here, a thieno[3

Electrostatic compaction of double stranded DNA induced by a positively charged poly(amidoamine) (PAMAM) dendrimer of generation four (G4) was found to produce two unique types of DNA mesophases, in which the DNA bent into superhelices packed in a tetragonal or hexagonal lattice. The structure formed at a lower dendrimer charge density was three-dimensionally (3D) ordered, as characterized by the P41212 space group with a 41 screw axis in a tetragonal arrangement, showing that the weakly bent DNA superhelices with a pitch length of ca. 5.0 nm possessed both identical handedness and phase conservation. The 3D ordered structure transformed into a 2D mesophase at a higher dendrimer charge density, wherein the strongly bent superhelices with a pitch length of ca. 4.0 nm organized in a hexagonal lattice without lateral coherence of helical trajectory. The counterion valency of the protonic acid that is used to charge the dendrimer was found to influence the phase diagram. Under a given dendrimer charge density, the complex with a multivalent acid-protonated dendrimer tended to form structures with less curved DNA, attesting that the driving force of charge matching was reduced by increasing the counterion valency of the dendrimer.

Sub-monolayer Pt-modified Au dendrites (Au-Ds) were successfully synthesized and characterized using several techniques. The resulting Pt-modified Au-Ds effectively combined component catalytic properties and plasmonic optical properties. Results obtained from comprehensive kinetics experiments revealed that Pt-modified Au-Ds serve as an ideal photoelectocatalyst for the formic acid oxidation reaction (FAOR). Electro- and photoelectrocatalytic FAOR was carried out via the same dehydrogenation pathway on a high-efficiency Pt-modified Au-D surface with a low activation energy of 35.4 kJ mol−1. The contribution from the photo-enhanced electrocatalytic effect reached 68% in the Tafel region. Photoelectrocatalysis and the photo-thermal effect synchronously boosted the FAOR on Pt-modified Au-Ds under illumination. Chronoamperometry results indicated that Pt-modified Au-Ds exhibit excellent stability and long-term durability for the FAOR.

Long term success of metallic fusion cages depends on mechanobiological processes through the bone incorporation and rich osseointegration. An optimal configuration of porous titanium-aluminum-vanadium (Ti 6Al 4V) implant fabricated via the additive manufacturing was evaluated in complimentary structure examinations to investigate the growth of autologous osseous at multi-length scales. X-ray microcomputed tomography (micro-CT) and transmission X-ray microscopy (TXM) using newly-built analysis method indicate the porous Ti 6Al 4V is much better for bone ingrowth compared to commercially non-porous titanium (Ti) and porous tantalum (Ta) implants at the ultramicrostructural level. The evolution of bone formation and remodeling acquired by nano X-ray Laue diffraction mapping exhibits the isotropic orientation and low crystallinity of all newly formed bone whereas mature bone in Ti 6Al 4V discloses the preferential alignment and higher crystallinity volumes of constituent hydroxyapatite (HA) crystallites. The high degree in mineral crystallinity of the fully mature bone suggests additive manufactured Ti 6Al 4V pores enhance the collagen-regulated mineralization.

This study proposes the prototype of a wrist pulse acquisition device with three-dimensional pulse image (3DPI) obtained at the radial artery. The proposed prototype is designed with mechanical and electronic circuit hardware as well as the control and data acquisition software to have fourteen degrees of movement freedom against the sophisticated geometry of the wrist radial artery for accurate pulse-taking. Three robot fingers with nine degrees of movement freedom and a wrist fixer with two degrees of rotation freedom and one degree of manual movement freedom are designed to mimic the fine pulse-taking skill of a Chinese medicine physician. The customer-designed array sensors with $5\times5$ -1 sensing elements in an array are attached on the robot fingertips to get 3DPI with spatial information for direct translation of pulse feeling patterns in Chinese medicine texts, in addition to being compatible with 1D pulse wave analysis. To check reliability of the prototype, adopted is SphygmoCor with pulse data correlation. Consequently, the prototype passes safety tests and has high correlation of pulse data (waveform and peripheral augmented index) with those obtained by SphygmoCor. The automatic multi-depth pulse-taking with robot fingers attached array sensors on their tips can get acceptably repeatable pulse data with coefficient of variation less than 10%. By simultaneous pulse-taking at Cun-Guan-Chi positions, 3DPIs demonstrate great different stereoscopic waveshapes against almost unchanged single temporal pulse waveshape. Hence, the proposed prototype may be a useful tool to perform array pulse-taking for Chinese medicine pulse diagnosis and pulse wave analysis for cardiovascular examination.

The combination of a bulk 3D perovskite layer and a reduced dimensional perovskite layer (perovskite quantum wells (PQWs)) is demonstrated to enhance the performance of perovskite solar cells (PSCs) significantly in terms of stability and efficiency. This perovskite hierarchy has attracted intensive research interest; however, the in-depth formation mechanism of perovskite quantum wells on top of a 3D perovskite layer is not clearly understood and is therefore the focus of this study. Along with ex situ morphology and photophysical characterization, the time-resolved grazing-incidence wide-angle X-ray scattering (TS-GIWAXS) technique performed in this study provides real-time insights on the phase-transition during the organic cation (HTAB ligand molecule) coating and PQWs/3D architecture formation process. A strikingly strong ionic reaction between the 3D perovskite and the long-chain organic cation leads to the quick formation of an ordered intermediate phase within only a few seconds. The optimal PQWs/3D architecture is achieved by controlling the HTAB casting, which is assisted by time-of-flight SIMS characterization. By controlling the second ionic reaction during the long-chain cation coating process, along with the fluorinated poly(triarylamine) (PTAA) as a hole-transport layer, the perovskite solar cells demonstrate efficiencies exceeding 22% along with drastically improved device stability.

Hypothesis Multistage silicate self-organization into light-weight, high-strength, hierarchically patterned diatom frustules carries hints for innovative silica-based nanomaterials. With sodium silicate in a biomimetic sol-gel system templated by a tri-surfactant system of hexadecyltrimethylammonium bromide, sodium dodecylsulfate, and poly(oxyethylene-b-oxypropylene-b-oxyethylene) (P123), mesoporous silica nanochannel plates with perpendicular channel orientation are synthesized. The formation process, analogous to that of diatom frustules, is postulated to be directed by an oriented self-assembly of the block copolymer micelles shelled with charged catanionic surfactants upon silication. Experiments The postulated formation process for the oriented silica nanochannel plates was investigated using time-resolved small-angle X-ray and neutron scattering (SAXS/SANS) and freeze fracture replication transmission electron microscopy (FFR-TEM). Findings With fine-tuned molar ratios of the anionic, cationic, and nonionic surfactants, the catanionic combination and the nonionic copolymer form charged, prolate ternary micelles in aqueous solutions, which further develop into prototype monolayered micellar plates. The prolate shape and maximized surfactant adsorption of the complex micelles, revealed from combined SAXS/SANS analysis, are of critical importance in the subsequent micellar self-assembly upon silicate deposition. Time-resolved SAXS and FFR-TEM indicate that the silicate complex micelles coalesce laterally into the prototype micellar nanoplates, which further fuse with one another into large sheets of monolayered silicate micelles of in-plane lamellar packing. Upon silica polymerization, the in-plane lamellar packing of the micelles further transforms to 2D hexagonal packing of vertically oriented silicate channels. The unveiled structural features and their evolution not only elucidate the previously unresolved self-assembly process of through-thickness silica nanochannels but also open a new line of research mimicking free-standing frustules of diatoms.

The terpolymers based on indacenodithiophene dicyanindenone derivative, named as PTer-N10, PTer-N25 and PTer-N50, were designed and synthesized by incorporating naphthalenediimide derivative with 10%, 25% and 50% molar ratios as another electron-withdrawing unit, respectively. These terpolymers were used as the acceptors to prepare all-polymer solar cells (all-PSCs) with o-xylene as the solvent and 2-methylnaphthalene as the additive without any annealing treatment, which showed high power conversion efficiency (PCE). The terpolymer PTer-N25 possesses the highest light harvest, the best morphology, the highest and most balanced charge mobilities in blend film, so the all-PSC based on PM6: PTer-N25 achieved the highest PCE of 11.94%. This study indicates that ternary polymerization is an efficient strategy to obtain green-solvent processing polymeric acceptors, which can achieve high-performance all-PSCs.

Direct binding of calcium ions (Ca2+) to phospholipid membranes is an unclarified yet critical signaling pathway in diverse Ca2+-regulated cellular phenomena. Here, high-pressure-liquid-chromatography, small-angle X-ray scattering (SAXS), UV–vis absorption, and differential refractive index detections are integrated to probe Ca2+-binding to the zwitterionic lipid membranes in nanodiscs. The responses of the membranes upon Ca2+-binding, in composition and conformation, are quantified through integrated data analysis. The results indicate that Ca2+ binds specifically into the phospholipid headgroup zone, resulting in membrane charging and membrane swelling, with a saturated Ca2+-lipid binding ratio of 1:8. A Ca2+-binding isotherm to the nanodisc is further established and yields an unexpectedly high binding constant K = 4260 M–1 and a leaflet potential of ca. 100 mV based on a modified Gouy–Chapman model. The calcium-lipid binding ratio, however, drops to 40% when the nanodisc undergoes a gel-to-fluid phase...

Membrane thinning that resulted from peptide-binding is observed via temperature dependent small-angle X-ray scattering (SAXS). The result reveals a mean thermal thinning rate of 0.038 Å K-1 for the neat unilamellar vesicles (ULVs) of a zwitterionic phospholipid of 1,2-dieicosenoyl-sn-glycero-3-phosphocholine (diC20:1PC) in the temperature range of 285-312 K. The thinning effect promotes greatly the association between a model antimicrobial peptide melittin and the ULV. Scaling the observed isothermal melittin-ULV bilayer thinning to that measured using low-angle X-ray diffraction from the melittin-multilamellar membranes of defined peptide-to-lipid ratios establishes temperature-dependent binding isotherms χb of the peptide-ULV as a function of free peptide concentration in solution. From the binding isotherms, temperature-dependent peptide-membrane binding constant K(T) is extracted on the basis of a modified Gouy-Chapman model. Changes in K(T) follow the linearized van't Hoff equation ln K(T) ∝ -ΔHT-1 with a constant enthalpy change ΔH = 9.6 kcal mol-1, suggesting an entropy-driven binding process prior to membrane pore formation. Correspondingly, a five-fold enhancement of K is observed in the temperature range studied. The peptide-binding strength is found to follow the growth trend of the membrane thermal thinning rate better than the lipid chain length of the three phosphocholine-based ULVs of diCn:1PC with n = 18, 20, and 22.

In eukaryotes, the compaction of chromatin fibers composed of nucleosome core particles (NCPs) connected by a linker DNA into chromosomes is highly efficient; however, the underlying folding mechanisms remain elusive. We used small angle X-ray scattering (SAXS) to investigate the influence of linker DNA length on the local structure and the interparticle interactions of the NCPs. In the presence of the linker DNA of 30 bp or less in length, the results suggest partial unwrapping of nucleosomal DNA on the NCP irrespective of the linker DNA length. Moreover, the presence of 15 bp linker DNA alleviated the electrostatic repulsion between the NCPs and prevented the formation of an ordered columnar hexagonal phase, demonstrating that the linker DNA plays an active role in chromatin folding. MOE (Min. of Education, S’pore) Accepted version

A new class of additive materials bis(pentafluorophenyl) diesters (BFEs) where the two pentafluorophenyl (C6F5) moieties are attached at the both ends of a linear aliphatic chain with tunable tether lengths (BF5, BF7, and BF13) were designed and synthesized. In the presence of the BF7 to restrict the migration of fullerene by hand-grabbing-like supramolecular interactions induced between the C6F5 groups and the surface of fullerene, the P3HT:PC61BM:BF7 device showed stable device characteristics after thermal heating at 150 oC for 25 h. The morphologies of the active layers were systematically investigated by OM, GISAXS, and AFM. The tether length between the two C6F5 groups plays a pivotal role in controlling the intermolecular attractions. BF13 with long and flexible tether might form a BF13-fullerene sandwich complex that fails to prevent fullerene’s movement and aggregation, while BF5 with too short tether length decreases the possibility of interactions between the C6F5 groups and the fullerenes. BF7...

The performance of quasi-2D perovskite light emitting diodes (LEDs) with mixed small cations, cesium and formamidinium (FA), is significantly affected by their ratio. The best devices obtained for Cs:FA ratio of 1:1 exhibit a maximum external quantum efficiency (EQE) of 12.1%, maximum luminance of 15 070 cd m−2 and maximum current efficiency of 46.1 cd A−1, which is significantly higher (about 3 times) compared to devices with FA only (maximum EQE of 4.1%, maximum luminance of 4521 cd m−2) and Cs-only (maximum EQE of 4.0%, maximum luminance of 4886 cd m−2). The photoluminescence quantum yield of the Cs:FA 1:1 sample is similarly enhanced, 21.3% compared 5.4% and 6%, for FA-only and Cs-only samples, respectively. It can be observed that the Cs:FA ratio significantly affects the crystallization of the perovskite, with the optimal 1:1 ratio resulting in the formation of tetragonal Cs0.5FA0.5PbBr3 phase (different from cubic FAPbBr3 and orthorhombic CsPbBr3) with pronounced preferential orientation as well as a significant reduction in the trap density, which leads to a substantial improvement in the light- emitting performance.

Conversion-type electrodes generally feature unstable cycling stability as an anode for Li ion batteries. In this work, however, we suggest that the weird capacity increase after initial decay during cycling is likely a common feature for the electrode materials undergoing high-rate conversion reaction. The cycling with α-Fe2O3 anodes at the current density of 500 mA g−1 or more could effectively trigger the typical capacity increase with cycle number after its initial degradation. Its morphological and structural evolutions during cycling are comprehensively characterized here by synchrotron X-ray scattering, X-ray absorption and photoelectron spectroscopies, and electron microscopy. The investigation demonstrates that enough fast conversion reaction tends to reduce the crystallite size of α-Fe2O3 significantly as a result of the electrochemical grinding and the continuous cycling can generate the Fe-Fe-Fe medium-range ordering terminated by long Fe-O bonds, which exploits a facile conversion reaction route catalyzing the dissociation of Li2O toward lower redox potential and faster kinetics. In details, higher heterogeneity, larger stress/strain and thinner solid-electrolyte interphase layer accompanied by fast conversion reaction in α-Fe2O3 can make its pristine crystallites smaller, finally extending the proportion of Fe-Fe-Fe ordering and thereby facilitating the conversion reaction for higher capacity during the following charge/discharge. Most importantly, the new structure enables excellent performance for the full cell, in contrast to the catastrophic failure of the pristine oxides. The structural evolution addressed in the study updates the understanding of conversion reactions and sheds light on novel types of conversion-type electrodes towards the full-cell application of conversion-reaction electrodes.

Low-dimensional perovskites have been widely studied as a promising candidate for realizing stable light-emitting diodes (LEDs). However, blue-light-emitting devices generally possess low stability associated with gradually red-shifted emission. To overcome this issue, the effect of zinc bromide (ZnBr2) addition on the regulation of the crystal structures of phenethylammonium and bromine-chlorine mixed inorganic perovskites (PEA-CsPbBrxCl3-x) is investigated. With the ZnBr2 addition, low-dimensional perovskite structures undergo morphological changes, such as thickening of their crystal structures and higher degree of crystal arrangement. Stoichiometric selective characterization reveals that perovskite bonding forces changed from Van der Waals with PEA to ionic with ZnBr2. Meanwhile, ZnBr2 can effectively address the ion defect filling and dimensional structure property switching. Consequently, the optimized ZnBr2-assisted PEA-CsPbBrxCl3-x LED is shown to deliver a high luminance of 1245 cd/m2 along with a high external quantum efficiency of 1.30%. Furthermore, this blue LED exhibits excellent spectral stability, for which only 3-nm red-shift on external excitation (0.1 to 5.0 mA) is observed. Our result clearly shows that ZnBr2 addition effectively improves the stability of blue light-emitting perovskites.