Physics

ABSTRACT The rapid development of self‐assembled monolayers (SAMs) has been instrumental in advancing the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs) to exceed 26%. However, benchmark SAMs are limited by stochastic assembly kinetics and weak interfacial coupling with the perovskite, which induce severe interfacial recombination and compromise device stability. Here, we developed an amino acid hydrochloride (AAH)‐mediated SAM to construct high‐performance PSCs. By systematically modulating the AAH alkyl spacer length, we elucidate an optimal steric profile that balances thermodynamic anchoring with kinetic intermolecular organization. This optimized AAH‐mediated SAM exhibits enhanced coverage, uniformity, and molecular packing density, stabilizing the interface via reduced defect density and refined energy level alignment. Moreover, the AAH terminal ammonium (–NH 3 + Cl − ) moieties establish a chemical bridge with the perovskite, effectively passivating interfacial defects and promoting stress‐free crystallization. Consequently, the devices based on AAH‐mediated SAMs delivered a champion PCE of 26.87% (certified at 26.33%) on a 0.058 cm 2 area and 25.90% on a 1‐cm 2 area. Encapsulated device exhibited excellent operational stability, retaining over 97.3% of its initial efficiency after 1100 h of continuous operation at the maximum power point in air.

ABSTRACT Understanding the role of intrinsic magnetic order on the oxygen evolution reaction (OER) requires careful consideration of the magnetic properties of both the catalytic surface and bulk under operating conditions. Because these often diverge from those of the pristine material, operando characterization that directly links magnetic behavior to catalytic activity is essential. Here, we investigate the magnetic properties of thin‐film OER catalysts using a combination of temperature‐dependent operando ferromagnetic resonance spectroscopy (FMR), ambient‐pressure X‐ray magnetic circular dichroism (XMCD), and operando X‐ray absorption spectroscopy (XAS). A direct correlation between changes in long‐range magnetic order and OER activity, with minimal changes in the catalyst's electronic state was observed. Non‐interacting ferromagnetic regions appear to contribute to enhanced activity at temperatures just above . The enhancement is further amplified when the thin film undergoes the bulk paramagnetic‐to‐ferromagnetic transition below . Our results suggest that interatomic spin‐exchange interactions, occurring within ferromagnetic regions and across the ferromagnetic bulk and between these atoms and adsorbates, dominate the observed OER enhancements, potentially augmented by short‐range spin‐polarized conduction effects. These findings highlight that local ferromagnetic order, governed by exchange interactions over a few unit‐cells, plays a crucial role in modulating surface reaction dynamics, offering mechanistic insight into spin‐dependent catalysis.

ABSTRACT In industrial alkaline water electrolysis (AWE), the long‐term operational stability of oxygen evolution reaction (OER) electrocatalysts under harsh conditions—including high current densities, concentrated alkaline electrolytes, and elevated temperatures—often takes precedence over intrinsic catalytic activity. Nevertheless, existing strategies aimed at enhancing catalyst stability remain insufficient. Herein, we propose a stability‐oriented alloy design strategy based on incorporating corrosion‐resistant Cr into a dual‐phase MnFeCoNiMo high‐entropy alloy. Notably, thermodynamically driven forces promote the spontaneous enrichment of Cr within the Mo‐rich domains. Subsequent selective dealloying enables the in situ formation of a self‐assembled, non‐occlusive 3D (Cr, M)O x ‐enriched protective network. Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) and electron probe microanalysis (EPMA) reveal the continuous self‐regenerating behavior and dynamic structural reorganization of this network during long‐term operation, which effectively reconciles the classic activity–stability trade‐off. As a result, the nanoporous (np) HEA‐CrMo electrode exhibits OER overpotentials of 184 mV at 10 mA cm −2 and 252 mV at 100 mA cm −2 , and sustains stable operation for over 5000 h at 1000 mA cm −2 in 6.0 M KOH. Furthermore, its scalability is demonstrated in a commercial alkaline water electrolyzer with an effective reaction area of 70.9 cm 2 during a 15‐day accelerated stress test.

Photocatalytic hydrogen peroxide (H₂O₂) production represents a promising pathway for solar-to-chemical energy conversion. Nevertheless, this process is constricted due to rapid recombination rate of photogenerated charge carriers. Herein, Nv-CNS/BiOBr-Pd heterojunction was constructed by integration of nitrogen vacancy carbon nitride (Nv-CNS), Bismuth oxybromide (BiOBr), and palladium nanoparticles. This ternary complex shows excellent H₂O₂ production performance, achieving a rate of 7990 μmol•g⁻¹•h⁻¹ under simulated sunlight irradiation. On the basis of the consequence of X-ray photoelectron spectroscopy and UV-vis diffuse reflection spectroscopy, the charge transfer mechanism conforms to a S-scheme heterojunction system, which is conducive to promote the separation and transfer of electrons while preserving excellent redox capacity. The existence of nitrogen vacancies provides active sites for reaction, and Pd nanoparticles strengths the response scope and absorption capacity of sunlight. This work establishes a reasonable strategy for catalyst applied to the photocatalytic hydrogen peroxide evaluation.

We present an overview of the role of generating functions in quantum mechanical contexts, mainly in the modern theory of polarization and in the study of quantum phase transitions. Generating functions enable the derivation of moments and cumulants, quantities which characterize the fluctuations of an underlying probability distribution. In all of the cases we review, the fluctuations are those of a quantum system. We show that the original formalism for geometric phases, in which a quantum system is taken around an adiabatic cycle, can be extended to the case when degeneracy points are encountered along the cycle (quasiadiabatic cycles). The essential tool for this extension is a generalized Bargmann invariant which plays the role of a generating function. From the cumulants generated this way one can form ratios according to the Binder cumulant scheme in statistical mechanics. Such geometric Binder cumulants are sensitive to gap closure, as such, they are useful in identifying metal-insulator, localization, and quantum phase transitions. We present example calculations on simple model systems whose localization properties are well known to validate to approach. We also complement our geometric Binder cumulant calculations with results for the fidelity susceptibility, a quantity directly related to the quantum geometry of the parameter space. CONTENTS I. Introduction 2 II. Basic ingredients 4 A. The problem of the polarization in crystalline systems 4 B. Generating functions, moments, cumulants 5 C. The excess kurtosis and the Binder cumulant 6 D. Berry phases 7 1. The Berry phase 7 2. The open path Berry phase (Zak phase) 8 3. The single point Berry phase 9 E. The generating function in quantum geometry 9 III. Generating functions in crystalline systems 9 A. Periodic probability distributions 10 B. The modern polarization theory for crystalline many-body systems 11 C. Gauge invariant cumulants 12 D. Generating functions for the Berry phase 12 E. Constructing the geometric Binder cumulant for quantum cycles 14 IV. Demonstrative examples 14 A. The Fermi sea 15 B. The Su-Schrieffer-Heeger model 16 C. Localization in the Aubry-André model 17 D. The Aubry-André transition through the fidelity suscebtibility 19 V. Conclusion 19.

The Su-Schrieffer-Heeger (SSH) model describes a tight-binding one-dimensional (1D) lattice with alternating nearest-neighbor amplitudes. Despite its mathematically simple and physically intuitive structure, the SSH model is capable of supporting a 1D topological phase that is characterized by the presence of zero energy eigenstates (zero modes) localized at each end of the lattice. For this reason, many studies in the area of topological phases of matter often consider the SSH model as a subject for various extensions that give rise to more sophisticated topological phenomena. The purpose of this article is to review, in sufficient detail, existing approaches to extending the SSH model. This includes extensions by increasing the dimensionality of the lattice, enlarging the size of its unit cell, or adding extra terms that represent various physical effects. For each approach, some extended SSH models studied in relevant existing literature are discussed as case studies. Noteworthy properties of such models, which are of topological origin, are further comprehensively elaborated.

We study the electronic band structure of low-buckled silicene, germanene, and stanene with triangular defects in the superhoneycomb arrangement by performing first-principles calculations within the framework of density functional theory. Our calculation results show that low buckling structures with triangular defects can generate flat bands. However, these flat bands have partial energy overlap with the adjacent bands. To address this issue, we introduced spin-orbit coupling, aiming to decouple the flat bands from the adjacent bands. Subsequent calculations confirmed that this method successfully produced isolated flat bands. It is particularly noteworthy that by introducing spin-orbit coupling, we have obtained the highest valence band with a bandwidth of only 0.005 eV in stanene with a specific configuration, which fully demonstrates the great potential of this system in achieving ultra-flat bands. This study successfully demonstrates that introducing periodic triangular defects and incorporating spin-orbit coupling in low-buckled silicene, germanene, and stanene is an effective strategy for generating isolated flat bands and achieving precise modulation of electronic states, providing a systematic theoretical pathway for the design of two-dimensional flat band materials.

The theoretically predicted Chern insulators have highlighted the potential of easy-axis kagome ferromagnets to host the quantum anomalous Hall effect. Similar topological phases may also arise from in-plane ferromagnetism through the breaking of certain mirror symmetries in kagome materials. In this work, we show that the interplay between magnetism and mirror symmetries makes ferromagnetic kagome systems a versatile platform for realizing nontrivial topological phases, with the orientation of magnetic moments m̂(θ, ϕ) at lattice sites serving as a key tuning parameter. We construct a symmetry-adapted minimal tight-binding model for kagome ferromagnets that includes intrinsic spin-orbit coupling (SOC) and the intrinsic Rashba SOC permitted by broken out-of-plane mirror symmetry between nearest-neighbor kagome sites, enabling us to capture the resulting topological phase diagram as a function of m̂(θ,ϕ). In particular, the restoration of in-plane mirror symmetry for specific values of ϕ drives a topological phase transition upon varying the in-plane orientation of the moments m̂(θ = 90◦ , ϕ). In contrast, for fixed ϕ, the transitions driven by varying θ originate from the competition between Rashba SOC and intrinsic SOC. Density functional theory calculations for the ferromagnetic kagome monolayer Co₃Pb₃S₂, a representative compound belonging to the family Co₃X₃Y₂(X = Sn, Pb; Y = S, Se), corroborate our predictions based on the proposed minimal tight-binding model.

This article reports an ab initio molecular dynamics investigation of the static 
structure, microscopic dynamics, transport coefficients and electronic properties of the 
liquid Fe$_{0.85}$Ni$_{0.15}$, Fe$_{0.90}$Ni$_{0.10}$ and 
Fe$_{0.79}$Ni$_{0.05}$S$_{0.16}$ alloys which have both geophysical and technological (Invar alloys) interest. 
The motivation is twofold: first, to provide a first-principles description of atomic-scale structure and 
dynamics in these alloys, for which experimental data on some transport properties remain scarce; and 
second, to investigate the influence of sulfur on the local order, 
collective excitations, and viscosity.
The calculated total static structure factors show excellent agreement with available neutron scattering
experiments, validating the fidelity of the simulations. 
Self-diffusion coefficients for Fe and Ni in the binary alloys are found to be nearly identical and in good agreement
with quasielastic neutron scattering data; the addition of sulfur substantially enhances diffusivity and reduces viscosity.
The collective dynamics exhibit propagating acoustic modes, from which adiabatic sound velocities are derived. 
Analysis of transverse current correlation spectra
uncovers, for the first time, the emergence of three distinct transverse branches in the dispersion relation of
the minority Ni component at low wavevectors; this is a phenomenon not previously observed in liquid metals and 
prompts further theoretical investigation. 
The electronic density of states confirms metallic behavior and provides evidence of S(3p)-Fe(3d) hybridization.

This study designs and synthesizes a novel asymmetric bis-heterocyclic compound: 3-(5-methyl-1,2,4-oxadiazol-3-yl)-5-(dinitromethyl)-1,2,4-oxadiazole and its ionic salts. The molecule is based on a rigid 3,3′-bis(1,2,4-oxadiazole) skeleton, with its two 5-positions substituted by complementary electron-donating methyl and strong electron-withdrawing dinitromethyl energetic groups, thereby constructing a unique “push–pull” electronic system. Among them, compounds 5–7 exhibit high thermal stability (177–271 °C) and favorable detonation performance (7019–7769 m s–1; 20.2–23.8 GPa), coupled with low mechanical sensitivity [friction sensitivity (FS) ≥ 320 N; impact sensitivity (IS) ≥ 32 J]. Notably, compound 6 demonstrates superior overall performance (Tdec = 208 °C, D = 7769 m s–1, P = 23.81 GPa, FS > 360 N, IS > 40 J). The unique structural design provides a valuable candidate platform for the future development of novel energetic materials or functional molecules. This work offers an effective strategy for the synthesis of asymmetric bis(1,2,4-oxadiazole) derivatives.

Topological isomerism between 2D and 3D networks in hydrogen-bonded organic frameworks (HOFs) has rarely been shown. Here, we show that a conformationally flexible tetracarboxylic acid PBQX assembles into either a 3D cds or two 2D sql networks, depending on the guest solvent used in crystallization. PBQX possesses a quinoxaline core with heterotype peripheral arms, 4-carboxyphenyl and 4-carboxybiphenyl groups. Single-crystal X-ray diffraction analysis revealed that bending distortions of the arm units and hydrogen bonding motifs allow the molecules to construct both 2D and 3D networks. Guest exchange of these crystals induced structural transformations without a loss of crystallinity, generating two additional isomers. Only the sql network preserved its topology during the transformation, indicating that the cds network is stabilized by interactions with specific guest molecules. Interaction energy calculations also confirmed that these guest–framework interactions compensate for the weaker framework stacking in the cds network. To probe the structure-topology correlation, we further synthesized an analogue, PBBrPQ, which possesses the same heterotype arms on a dibromopyrazinoquinoxaline core. PBBrPQ also gives two sql forms, but, in contrast to PBQX, does not access the cds network. These results indicate that “heterotype arm modulation” is an effective molecular design strategy to increase framework conformational flexibility and expand the structural diversity of HOFs.

Gelation and crystallization are two distinct yet interrelated molecular self-assembly manifestations. Despite both originating from the same molecular building blocks and relying upon weak noncovalent interactions, they represent orthogonal outcomes because the conditions that promote one pathway may not necessarily favor the other. This divergence in pathways stems from the manner in which the molecular interactions are expressed in space and time, the differences in molecular packing, and the relative influence of kinetic versus thermodynamic control of self-assembly. Physicochemical environment and stimuli triggers, such as temperature change, variation in solvent polarity, pH, mechanical agitation, and concentration, play vital roles in dictating which self-assembly pathway dominates and whether one pathway can be controlled or selectively manipulated with respect to the other. While orthogonality is evident, there is also a degree of interdependence and mutual influence of these pathways on one another. Gels can act as scaffolds or templates for crystallization by providing a uniform and ambient nucleation environment, thus giving rise to crystal outputs with desirable properties. In the case of molecules that are practically important but inherently challenging to crystallize via conventional methods, formation of a metastable gel state can even act as a precursor for the crystallization process. Thus, understanding the interplay between gelation and crystallization is not only limited to laboratory research but extends beyond it for applications ranging from the design of soft materials to pharmaceutical formulations and polymorph control of drug molecules. This review aims to bridge the long-standing gap between the realms of crystallization and gelation, highlighting the significance of studying the gel–crystal interface.

Herein, we investigate the solid-state structure of N,N′-diarylbenzamidines in their neutral and cation states. Depending on the conditions, all three possible conformations were observed. Specifically, the E/Z form was observed in the neutral state, the sterically unfavorable Z/Z form was commonly observed in the halide salts, and the E/E form was dominant in the carboxylate salts because of the discrete salt bridge formation. The rigid H-shaped structure of the E/E form of bis(N,N′-diaryl)benzdiamidine created highly solvated crystals combined with carboxylic acids.

Rational design of functional crystalline materials through molecular-level control remains a pivotal challenge in materials chemistry. While cation engineering has been extensively studied, the systematic exploitation of anion geometry as a structural “template” to modulate macroscopic optical anisotropy remains underexplored. Herein, we implement an anion-driven structural evolution strategy by pairing a high-polarizability organic cation, [C10H8NO2]+, with anions of divergent geometries: spherical (Cl–), planar (NO3–), and polyhedral (SiF62–). This evolution in the anionic configuration successfully steers the crystal packing from large-angle staggered to perfectly parallel alignment. Consequently, three novel UV birefringent crystals─[C10H8NO2]Cl·H2O (1), [C10H8NO2]NO3 (2), and [C10H8NO2]2SiF6·2H2O (3)─were synthesized. Notably, compound 3 exhibits a giant birefringence of 0.79 at 550 nm, significantly outperforming compounds 1 (0.31) and 2 (0.33) while maintaining a short UV cutoff edge (354 nm). Structural-property analysis reveals that the dimensional evolution of anions effectively modulates the alignment of optically active groups and the intermolecular stacking, thereby governing the macroscopic optical anisotropy. This work provides a quantitative mechanism-driven framework for the targeted design of high-performance optical materials via anion engineering.

Chiral resolution of racemic mixtures stems from the stereospecific interaction between chiral counterparts of the interacting species. Unlike diastereomeric resolution, resolution achieved by an achiral agent depends on the spontaneity introduced by nucleation free energy barriers of the enantiopure and racemic crystals. The spontaneous resolution during crystallization via conglomeration of racemic salts of Raloxifene Mandelate is the first instance of a salt-based resolution of (±)mandelic acid with Raloxifene free base as the achiral resolving agent. Various analytical techniques are employed to substantiate the formation of the racemate and the conglomerate. Comparative Hirshfeld surface analysis and solubility studies are reported to correlate the structure–property relationships of the solid phases obtained. The chiral resolution of the racemic mandelate salt is achieved through seeded isothermal preferential crystallization, resulting in an enantiopurity of 86% under ambient conditions. The in vitro cytotoxic activity of Raloxifene Mandelate salts is evaluated across a dual panel of phenotypically distinct breast cancer cell lines under different stereochemical compositions, indicating a relatively better stereospecific competence for Raloxifene-(R)-Mandelate compared to -(S)- form and the marketed hydrochloride salt formulation.