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Functional assessment of stem cell‐mediated endogenous repair relies on animal studies. Here an in vitro assay is described that recapitulates important early steps of the in vivo skeletal muscle endogenous repair (MEndR) process. The assay is integrated with a custom semi‐automated image analysis pipeline to enable high‐content data analysis of donor‐derived muscle fiber content and morphology. Myotube sheets, generated by infiltrating a cellulose scaffold with myoblasts, are engrafted with muscle stem cells (MuSCs), injured to induce a regenerative microenvironment, and muscle repair is assessed. Significantly, the spatiotemporal dynamics of in vitro repair closely matched those observed in vivo, when both stem cells and injury are present. By exploiting the easy imaging geometry of the engineered tissue, cellular mechanisms of action driving the MuSC response to the regenerative template are explored. In vivo outcomes of two known modulators of MuSC‐mediated repair, measured by donor fiber production, MuSC niche repopulation, and response to a secondary injury, are phenocopied in the platform only when both the stem cells and injured 3D template are present. The MEndR platform represents a powerful opportunity to explore MuSC‐mediated repair and potentially compress the discovery pipeline by combining drug screening and validation in one step. [ABSTRACT FROM AUTHOR]

Self‐trapped exciton (STE) emission of low‐dimensional metal halides has witnessed explosive developments in both display and illumination, due to its intriguing photoluminescence properties. As one typical feature, STE emission energy is commonly independent of excitation wavelength. Herein, a rare phenomenon of inverse excitation‐dependent dual‐band emission is achieved on 0D Cs2InBr5·H2O. Under initial compression, the contraction of inhomogeneously coordinated InBr5O octahedra gives rise to blue‐shifted STE emission with the decreased Stokes shift. As the phase transition occurs under higher pressure, considerable octahedral distortions generate a new defect‐related localized exciton emission. Notably, the high‐energy emission from the intrinsic STE state is only observed under the low‐energy excitation, which is believed to originate from the excitation‐dependent multiple excited states in high‐pressure Cs2InBr5·H2O. [ABSTRACT FROM AUTHOR]

Highly efficient lead halide perovskites with tunable emission performance have become new candidate materials for light‐emitting devices and displays; however, the toxicity of lead and instability of halide perovskites greatly limits their application. Herein, rapid and large‐scale synthesis of highly emissive organic–inorganic manganese halide perovskites, (C5H6N)2MnBr4 and C5H6NMnCl3, are presented by a one‐pot solution‐based method, of which (C5H6N)2MnBr4 displays a high absolute photoluminescence quantum yield (95%) in the solid‐state. The developed (C5H6N)2MnBr4 perovskite noticeably exhibits high stability. Therefore both as‐synthesized green and red emissive manganese‐based phosphors with superior optical properties are used to fabricate blue light pumped white light‐emitting diodes (WLEDs), displaying excellent quality white light with a high color rendering index value of 91 and a correlated color temperature of 5331 K. This study not only presents the robust large‐scale production synthetic approach for organic–inorganic manganese halide perovskites, but also facilitates the development of high‐performance phosphors for future lighting and display technologies. [ABSTRACT FROM AUTHOR]

A first‐principles‐based effective Hamiltonian is developed and employed to investigate finite‐temperature structural properties of a prototype of perovskite halides, that is CsPbI3. Such simulations, when using first‐principles‐extracted coefficients, successfully reproduce the existence of an orthorhombic Pnma state and its iodine octahedral tilting angles around room temperature. However, they also yield a direct transformation from Pnma to cubic Pm3¯m upon heating, unlike measurements that reported the occurrence of an intermediate long‐range‐tilted tetragonal P4/mbm phase in‐between the orthorhombic and cubic phases. Such disagreement, which may cast some doubts about the extent to which first‐principle methods can be trusted to mimic hybrid perovskites, can be resolved by "only" changing one short‐range tilting parameter in the whole set of effective Hamiltonian coefficients. In such a case, some reasonable values of this specific parameter result in the predictions that i) the intermediate P4/mbm state originates from fluctuations over many different tilted states; and ii) the cubic Pm3¯m phase is highly locally distorted and develops strong transverse antiphase correlation between first‐nearest neighbor iodine octahedral tiltings, before undergoing a phase transition to P4/mbm under cooling. [ABSTRACT FROM AUTHOR]

Since the first report on 2D Ti SB 3 sb C SB 2 sb in 2011, an escalating number of studies have been targeting synthesis, compelling properties, and versatile applications of MXenes. The structural configuration in which transitional metal atoms are arranged in a layered fashion with carbon or nitrogen atoms, allows MXenes to enjoy extraordinary compositional diversity and adjustable properties. Nguyen et al. (article number 1909504) review the inherent advantages of MXenes in actuator devices, covering the structural and compositional superiority of MXenes with a focus on state-of-the-art photothermal, electrothermal, and humidity-responsive MXene-based actuators. [Extracted from the article]

Currently, the most popular way to manufacture white light‐emitting diodes (WLEDs) is based on blue‐emitting InGaN LED chips (440–460 nm) and yellow‐emitting phosphor coating (520–700 nm) to produce white light lighting. However, because conventional white WLEDs lack the uniformly distributed continuous emission spectrum compared to natural sunlight: "blue overshoot" (extra 440–460 nm blue‐light can cause damage to the retina) and "cyan gap" (470–520 nm wavelength range). Here, a novel strategy to "kill two birds with one stone" is reported: using the stable and bright polymer encapsulated perovskite nanocrystals (PNCs) composite films as the cyan color converters that efficiently absorb the "blue overshoot" and effectively emit the cyan light to fill the "cyan gap". A series of polymer‐encapsulated PNC films is achieved that can reach very high photoluminescence quantum yield (PL QY) of 90–95% under 450 nm blue‐light excitation. Importantly, both 370 nm UV‐excited WLED and 455 nm blue‐excited WLED devices are constructed that exhibit smoothly and evenly distributed white light without blue overshoot and cyan gap, which was not achieved before for blue‐excited cyan‐emissive materials. This study paves the way toward the application of PNC color converters in the next generation full‐visible‐spectrum WLED lighting that mimic the natural daylight. [ABSTRACT FROM AUTHOR]

The so-called hybrid improper ferroelectricity (HIF) mechanism allows to create an electrical polarization by assembling two nonpolar materials within a superlattice. It may also lead to the control of the magnetization by an electric field when these two nonpolar materials are magnetic in nature, which is promising for the design of novel magneto-electric devices. However, several issues of fundamental and technological importance are presently unknown in these hybrid improper ferroelectrics. Examples include the behaviors of its polarization and dielectric response with temperature, and the paths to switch both the polarization and magnetization under electric fields. Here, an effective Hamiltonian scheme is used to study the multiferroic properties of the model superlattice (BiFeO3)1/(NdFeO3)1. Along with the development of a novel Landau-type potential, this approach allows to answer and understand all the aforementioned issues at both microscopic and macroscopic levels. In particular, the polarization and dielectric response are both found to adopt temperature dependences, close to the phase transition, that agree with the behavior expected for first-order improper ferroelectrics. And most importantly, a five-state path resulting in the switching of polarization and magnetization under an electric field, via the reversal of antiphase octahedral tiltings, is also identified. [ABSTRACT FROM AUTHOR]

Rare-earth substitution in the multiferroic BiFeO3 (BFO) material holds promise for resolving drawbacks inherent to pure BFO, and for enhancing piezoelectric and magneto-electric properties via a control of structural and magnetic characteristics. Rare-earth-doped BFO solid solutions also exhibit unresolved features, such as the precise nature and atomic characteristics of some intermediate phases. Here, an effective Hamiltonian scheme is developed that allows the investigation of finite-temperature properties of these systems from an atomistic point of view. In addition to reproducing experimental results of Nd-doped BFO on structural and magnetic transitions with temperature and composition, this scheme also provides an answer (in form of nanotwins) to these intermediate phases. A striking magneto-electric effect-namely a paramagnetic-to-antiferromagnetic transition that is induced by an applied electric field-is further predicted near critical compositions, with the resulting structural path being dependent on the orientation of the electric field relative to the antiferroelectric vector. [ABSTRACT FROM AUTHOR]

For the development of electrolyte additives as an effective strategy to improve the performance of zinc‐ion batteries (ZIBs), most researchers focus on the functional groups but overlook the crucial molecular configuration. Herein, six stereoisomers of 2,3,4,5‐tetrahydroxyvaleraldehyde with identical groups but various spatial arrangements are studied as the electrolyte additive in ZIBs. Based on the experimental analysis and theoretical calculations, the adsorption with Zn (002) plane is found to be an important dominant for the stereoisomer to enhance the Zn anode performance. Among these stereoisomers, D‐Arabinose with preferential and strongest chemisorption effect modifies the anode/electrolyte interface most effectively, leading to the highest stability and reversibility of the Zn anode. The adsorbed D‐Arabinose shows multifunctional effects at the interface, which not only regulates the Zn2+ solvation structure and reconfigures the hydrogen bond framework, but also facilitates uniform Zn2+ deposition by promoting 3D Zn2+ diffusion and homogenizing the electric field. Therefore, with the D‐Arabinose additive in ZnSO4 electrolyte, the undesired Zn dendrite growth and side reactions including hydrogen evolution reaction, corrosion, and passivation are significantly limited during the Zn plating/stripping processes. This work proposes a new insight toward the optimal molecular configuration of additive designing for electrolyte engineering in stable ZIBs. [ABSTRACT FROM AUTHOR]

Silicon‐based materials are regarded as the most promising negative electrode materials for next‐generation high‐energy lithium ion batteries due to their high theoretical capacity, low lithiation plateau and low cost, but they still suffer from dramatic volume variation during charge/discharge and sluggish kinetics, substantially restricting their practical applications. Recently, 2D MXenes are demonstrated to improve the electrochemical performances of Si‐based materials owing to their metallic conductivity, large surface aspect ratio, rich surface chemistry, good mechanical strength, etc. Serving as conductive host, MXenes can alleviate the volume expansion of Si during lithiation, enhance the electronic conductivity of the composite and facilitate the electron/ion transport, thus making the resultant Si/MXene composites exhibit excellent performance as negative electrodes of secondary batteries. Herein, an overview toward the recent advances of Si/MXene nanocomposites is presented for lithium storage applications. The preparation strategies and structural characteristics of the Si/MXene nanocomposites are introduced. The applications of diverse Si/MXene nanostructures such as powders, 3D architectures, films and fibers, in lithium ion batteries with corresponding structure‐performance relationships are discussed. Finally, the challenges and perspectives for the future research of Si/MXene nanocomposites are highlighted, aiming to provide a fundamental reference in designing advanced Si/MXene nanocomposites for high‐energy lithium ion batteries. [ABSTRACT FROM AUTHOR]

BiFeO3 is recognized as the most important room temperature single phase multiferroic material. However, the weak magnetoelectric (ME) coupling remains as a key issue, which obstructs its applications. Since the magnetoelectric coupling in BiFeO3 is essentially hindered by the cycloidal spin structure, here efforts to improve the magnetoelectric coupling by destroying the cycloidal state and switching to the weak ferromagnetic state through symmetry modulation are reported. The structure is tuned from polar R3c to polar Pna21, and finally to nonpolar Pbnm by forming Bi1‐xNdxFeO3 solid solutions, where two morphotropic phase boundaries (MPBs) are detected. Greatly enhanced ferroelectric polarization is obtained together with the desired weak ferromagnetic characteristics in Bi1‐xNdxFeO3 ceramics at the compositions near MPBs. The change of magnetic state from antiferromagnetic (cycloidal state) to ferromagnetic (canted antiferromagnetic) is confirmed by the observation of magnetic domains using magnetic force microscopy. More interestingly, combining experiments and first‐principles‐based simulations, an electric field‐induced structural and magnetic transition from Pna21 back to R3c is demonstrated, providing a great opportunity for electric field‐controlled magnetism, and this transition is shown to be reversible with additional thermal treatment. Electric field‐controlled magnetism is achieved in Bi1‐xNdxFeO3 solid solutions by tuning the symmetry from polar R3c to polar Pna21. The electric field‐controlled magnetism is realized by an electric field‐induced structural and magnetic transition from Pna21 back to R3c, and this transition is shown to be reversible with additional thermal treatment. [ABSTRACT FROM AUTHOR]

The large‐scale deployment of aqueous Zn‐ion batteries is hindered by Zn anode instability including surface corrosion, hydrogen gas evolution, and irregular Zn deposition. To tackle these challenges, a polyhydroxylated organic molecular additive, trehalose, is incorporated to refine the solvation structure and promote planar Zn deposition. Within solvation structure regions involving trehalose, the hydroxy groups participate in the reconstruction of hydrogen bond networks, which increases the overpotential for water decomposition reaction. Moreover, at the Zn metal–molecule interface, the chemisorption of trehalose onto the surface of the zinc anode enhances corrosion resistance and facilitates the deposition of zinc in a planar manner. The optimized electrolyte significantly improves Zn striping/plating reversibility and maintains stable potentials over 1600 h at 5 mA cm−2 with a cutoff capacity of 1 mA h cm−2 in symmetric cells. When combined with the MnO2 cathode, the assembled coin cell retains ≈89% of its capacity after 1000 cycles. This organic molecule additive, emphasizing the role of polyhydroxylated organic molecules in fine‐tuning solvation structures and anode/electrolyte interfaces, holds promise for enhancing various aqueous metal batteries. [ABSTRACT FROM AUTHOR]

Zn anode is a promising candidate for aqueous batteries, but suffers from the dendrite growth and side reaction issues, leading to short cycling life and unsatisfactory reversibility. Herein, a Cu‐modified Ti3C2Cl2 MXene (Cu‐MXene) with high zincophilic and hydrophobic property is prepared with a one‐step molten salt etching method. Serving as a protective coating on Zn anode, the Cu‐MXene can provide massive nucleation sites and uniformize the charge distribution, leading to homogenous Zn deposition. Moreover, the hydrophobic coating can prevent the Zn anode from the aqueous electrolyte, beneficial for suppressing the side reactions such as hydrogen evolution reaction and corrosion. Therefore, the stable and reversible Zn plating/stripping is achieved for the Zn anode coated by the Cu‐MXene, which delivers an extended cycling life of over 1000 h with a low polarization within 120 mV at 10 mA cm−2, and a high coulombic efficiency of over 99.6% for 1100 cycles, indicating excellent stability and reversibility of Zn stripping/plating. The practical full cell coupled with NaV3O8·1.5H2O cathode also displays stable performance for 1000 cycles. The proposed Cu‐MXene coating reveals a promising prospect for designing highly stable Zn anode, which can also be extended to other energy storage systems based on metal anodes. [ABSTRACT FROM AUTHOR]

Multiferroic materials are currently attracting a lot of interest because of the cross-coupling between their electrical and magnetic properties, which has the potential to lead to novel devices. There is a relatively small number of multiferroics and, hence, various strategies have been proposed to design materials possessing both ordered electric and magnetic dipoles. However, one strategy that has been scarcely investigated so far is the application of hydrostatic pressure because such external factor has the tendency to suppress, rather than enhance or create, electrical polarization. Here, first-principles calculations are used to demonstrate that hydrostatic pressure can, in fact, stabilize a novel polar and magnetic - and thus multiferroic - phase; the occurrence of such a phase seems very general, as it is found in many presently investigated RMnO3 compounds, where R is a rare-earth ion. The predicted structure features original pseudo Jahn-Teller effects that induce a spontaneous electrical polarization via a previously unknown structural coupling of a rather convenient form. Such a discovery opens a new route to create multiferroics and tunable electronic devices. [ABSTRACT FROM AUTHOR]

2D MXenes have emerged as promising supercapacitor electrode materials due to their metallic conductivity, pseudo‐capacitive mechanism, and high density. However, layer‐restacking is a bottleneck that restrains their ionic kinetics and active site exposure. Herein, a carbon dots‐intercalated strategy is proposed to fabricate flexible MXene film electrodes with both large ion‐accessible active surfaces and high density through gelation of calcium alginate (CA) within the MXene nanosheets followed by carbonization. The formation of CA hydrogel within the MXene nanosheets accompanied by evaporative drying endow the MXene/CA film with high density. In the carbonization process, the CA‐derived carbon dots can intercalate into the MXene nanosheets, increasing the interlayer spacing and promoting the electrolytic diffusion inside the MXene film. Consequently, the carbon dots‐intercalated MXene films exhibit high volumetric capacitance (1244.6 F cm−3 at 1 A g−1), superior rate capability (662.5 F cm−3 at 1000 A g−1), and excellent cycling stability (93.5% capacitance retention after 30 000 cycles) in 3 m H2SO4. Additionally, an all‐solid‐state symmetric supercapacitor based on the carbon dots‐intercalated MXene film achieves a high volumetric energy density of 27.2 Wh L−1. This study provides a simple yet efficient strategy to construct high‐volumetric performance MXene film electrodes for advanced supercapacitors. [ABSTRACT FROM AUTHOR]

Deterministic control of substitution sites is the holy grail of chemical engineering in materials science. The substitution of the dopants in the host crystal lattice usually obeys the empirical Hume‐Rothery rules, in which the mismatch of atomic size must be small and thus site‐specific. Herein, we report an unconventional case of mixed‐site substitution in highly‐strained BiFeO3 thin films. Driven by the delicate balance between chemical strain and epitaxial strain energies, the solid‐solution system demonstrates a self‐regulation behavior in dopant site occupancy to minimize the total free energy. This proposed mechanism offers valuable insight into the chemical substitution pathway in epitaxial thin films and provides a potential route to selectively control the substitution sites. [ABSTRACT FROM AUTHOR]

Lattice dynamics are often regarded as signatures of the underlying crystal structure. Here, a first‐principle‐based effective Hamiltonian method combined with molecular dynamics simulations is used to study dynamical behaviors of CsPbI3 perovskite across temperature and structural phase transitions. A single (short‐range tilting) parameter in this effective Hamiltonian is varied in order to make the temperature range of the intermediate tetragonal P4/mbm phase, existing in‐between the cubic Pm3¯m and orthorhombic Pnma phases, either broader than observed or completely disappearing. Comparing the dynamics of these different cases allows one to conclude that real CsPbI3 perovskite should have i) two iodine‐octahedral‐tilt related modes that differ in frequency but both significantly soften as the temperature decreases within the cubic phase toward the Pm3¯m‐to‐P4/mbm transition; and ii) one mode that maintains a very low frequency (of the order of 1.0 cm−1) in the entire region of P4/mbm stability, as a result of the temporal exploration of various structural states. Such latter sub‐THz mode mixes fluctuations of antiphase iodine tiltings and Cs antipolar motions because of a trilinear energetic coupling. [ABSTRACT FROM AUTHOR]

Graphite anodes show great potential for potassium storage, however, their capacity fades quickly owing to substantial interlayer expansion/shrinkage (i.e., up to 60%) induced structural degradation. Here, Ti3C2Tx MXene nanosheets are used as a fast electron/potassium‐ion dual‐function conductor to construct the framework of all‐integrated graphite nanoflake (GNF)/MXene (GNFM) electrodes. The continuous MXene framework constructs a 3D channel for fast electron/potassium‐ion transfer and endows GNFM electrodes with a high structural stability. Owing to this unique MXene framework, GNFM electrodes exhibit much enhanced potassium storage performances than that of the conventional polymer‐bonded electrodes even at high mass loadings. Moreover, GNFM electrodes also show impressive cyclability in non‐flammable electrolytes and are further used as anodes to assemble novel non‐flammable potassium‐ion capacitors that show an excellent cyclability and high energy/power densities (113.1 Wh kg–1 and 12.2 kW kg–1). New insights into phase transition mechanism in GNFM electrodes are verified by operando XRD. Density functional theory calculations demonstrate that MXene can promote electron transfer and potassium diffusion in the heterointerface between GNF and MXene. Therefore, the results demonstrate that all‐integrated GNFM electrodes designed with MXene as multifunctional frameworks provide a new paradigm for producing efficient potassium storage anodes. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries with a theoretical energy density of 2567 Wh kg−1 are very promising next‐generation energy storage systems, but suffer from the insulativity of sulfur and Li2S, the shuttle effect due to the dissolution and migration of polysulfides, and the lithium dendrite issue. MXenes, a family of 2D transition metal carbides/nitrides, which have metallic conductivity, structural variety, strong chemical adsorption ability to polysulfides, effective catalytic effect for fast kinetics, and inducing effect for uniform growth of Li, exhibit promising potential for high‐performance Li–S batteries. In this review, the recent progress and achievements of MXene‐based Li–S batteries are summarized, including the use of MXenes in sulfur cathode, interlayer between cathode and separator, and Li anode. The architecture construction and chemical modification of MXenes, as well as hybridization with other materials are demonstrated. The enhancement on electrochemical performance and the related mechanisms of MXenes and MXene‐based composites are discussed. Finally, challenges and perspectives of MXenes for Li–S battery application are also given. [ABSTRACT FROM AUTHOR]

MXenes with metallic conductivity, high pseudo‐capacitance and 2D structure, are promising flexible electrode materials for supercapacitors, but suffer from the restacking issue, which hinders ion accessibility and causes sluggish ion kinetics. Herein, a simple in situ ice template strategy is proposed to fabricate free‐standing, flexible 3D porous Ti3C2Tx/carbon nanotubes (CNTs) film (3D‐PMCF) by freeze‐drying Ti3C2Tx‐based hydro‐films without any postprocessing. During the freeze‐drying process, small ice grains are in situ transformed from the residual water molecules in the Ti3C2Tx interlayer and then act as a self‐sacrifice template to construct a 3D porous network. CNTs introduced in the hydro‐film increase the amount of interlayer water and the resultant porosity. The 3D structure of Ti3C2Tx significantly increases the exposed surface active sites and accelerates the ion transport, meanwhile maintaining good flexibility. Consequently, the flexible 3D‐PMCF film delivers a capacitance of 375 F g−1 at 5 mV s−1 and retains 251.2 F g−1 at 1000 mV s−1 with excellent cycling stability, much superior to the conventional densely stacked Ti3C2Tx film. Being assembled into a symmetric supercapacitor, an energy density of 9.2 Wh kg−1 is realized. This work demonstrates a simple and efficient route for constructing high‐performance and flexible 3D MXene film electrodes for supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: Simultaneously integrating efficient optical gain and high charge carrier mobility in organic semiconductors for multifunctional optoelectronic applications is challenging. Here, a new thiophene/phenylene derivative, 5,5′‐bis(2,2‐diphenylvinyl)‐bithiophene (BDPV2T), containing an appropriate butterfly molecular configuration in a π‐conjugated structure, is designed to achieve both solid‐state emission and charge transport properties. The prepared BDPV2T crystals exhibit excellent light‐emitting characteristics with a photoluminescence quantum yield of 30%, low light‐amplification threshold of 8 kW cm−2, high optical net gain up to 70 cm−1, and high charge carrier mobility up to 1 cm2 V−1 s−1 in their J‐aggregate single crystals. These BDPV2T single crystal characteristics ensure their application potential for photodetectors, field‐effect transistors, and light‐emitting transistors. High optoelectronic performances are achieved with photoresponsivity of 2.0 × 103 A W−1 and light on/off ratio of 5.4 × 105 in photodetectors, and efficient ambipolar charge transport (µh: 0.14 cm2 V−1 s−1, µe: 0.02 cm2 V−1 s−1) and electroluminescence characteristics in light‐emitting transistors. The remarkably integrated optoelectronic properties of BDPV2T suggest it is a promising candidate for organic multifunctional and electrically pumped laser applications. [ABSTRACT FROM AUTHOR]

Organic single crystals have a great potential in the field of organic optoelectronics because of their advantages of high carrier mobility and high thermal stability. However, the application of the organic single crystals in light-emitting devices (OLEDs) has been limited by single-layered structure with unbalanced carrier injection and transport. Here, fabrication of a multilayered-structure crystal-based OLED constitutes a major step toward balanced carrier injection and transport by introducing an anodic buffer layer and electron transport layer into the device structure. Three primary color single-crystal-based OLEDs based on the multilayered structure and molecular doping exhibit a maximum luminance and current efficiency of 820 cd cm−2 and 0.9 cd A−1, respectively, which are the highest performance to date for organic single-crystal-based OLEDs. This work paves the way toward high-performance organic optoelectronic devices based on the organic single crystals. [ABSTRACT FROM AUTHOR]

The molecular crystals of acridonyl-tetraphenylethene (AD-TPE) exhibit an intriguing turn-on and color-tuned luminescence in response to mechanical grinding and hydrostatic compression. On the basis of in-depth experimental and computational studies, it is hypothesized that the origin of the piezochromic behavior from the D-phase to the B-phase is the change of the intramolecular geometrical conformation, especially for the torsion angle between the TPE and AD moiety. The different molecular conformation in the two distinctive solid phases causes the substantial switching of the intra­molecular charge transfer (ICT) process, which can be directly correlated with the subsequent fluorescence from locally excited (LE) state and ICT state in both phases. The AD-TPE molecular system presents a very rare example of high-contrast reversible fluorescence tuning driven by a switching of the excited state in the solid state under the mechanical stimuli, and thus provides a novel mechanism of the piezochromic behavior. [ABSTRACT FROM AUTHOR]

Hard carbon (HC) is a promising anode material for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs), but the volume change during the insertion/extraction of Na+ or K+ limits the cycle life, especially for PIBs due to the large ion size of K+. Moreover, the conventional anodes fabricated through the coating method cannot satisfy the requirement of flexible devices. Here, it is shown that 2D carbide flakes of Ti3C2Tx MXene can be used as multifunctional conductive binders for flexible HC electrodes. The use of MXene nanosheets eliminates the need for all the electrochemically inactive components in the conventional polyvinylidene fluoride–bonded HC electrode, including polymer binders, conductive additives, and current collectors. In MXene‐bonded HC electrodes, conductive and hydrophilic MXene 2D nanosheets construct a 3D network, which can effectively stabilize the electrode structure and accommodate the volume expansion of HC during the charge/discharge process, leading to an enhanced electrode capacity and excellent cycle performance as anodes for both SIBs and PIBs. Benefiting from the 3D conductive network, the MXene‐bonded HC film electrodes also present improved rate capability, indicating MXene is a very promising multifunctional binder for next‐generation flexible secondary rechargeable batteries. [ABSTRACT FROM AUTHOR]

Turn‐on and color‐tuned piezochromic luminescence of acridonyl‐tetraphenylethene(AD‐TPE) with high‐contrast is obtained by B. Xu, W. Tian, and colleagues in response to external mechanical stimuli. The results on page 4005 indicate that the unique behavior is driven by a switching of the excited state in solid state from localized excited (LE) state to intramolecular charge transfer (ICT) state under mechanical stimuli, which will inspire a new approach to realize the piezochromic luminescent materials and give a new insight into the nature of the piezochromic behavior. [ABSTRACT FROM AUTHOR]