Regulation of the Buried Interface to Achieve Efficient HTL-Free All-Inorganic CsPbIBr-Based Perovskite Solar Cells.

The large voltage loss () mainly stems from the mismatch between the perovskite film and electron transport layer in CsPbIBr-based all-inorganic perovskite solar cells (I-PSCs), which restricts the power conversion efficiency (PCE) of devices. To address this issue, potassium benzoate (BAP) is first introduced as a bifunctional passivation material to regulate the TiO/CsPbIBr interface, reduce the , and improve the photovoltaic performance of CsPbIBr-based I-PSCs. Eventually, the champion PCE of CsPbIBr-based I-PSCs without a hole transport layer modified by BAP (Target-PSCs) improves to 14.

Ultrafast Switching of Sliding Polarization and Dynamical Magnetic Field in van der Waals Bilayers Induced by Light.

Sliding ferroelectricity is a unique type of polarity recently observed in van der Waals bilayers with a suitable stacking. However, electric-field control of sliding ferroelectricity is hard and could induce large coercive electric fields and serious leakage currents that corrode the ferroelectricity and electronic properties, which are essential for modern two-dimensional electronics and optoelectronics. Here, we proposed laser-pulse deterministic control of sliding polarization in bilayer hexagonal boron nitride by first principles and molecular dynamics simulation with machine-learned force fields.

Multifunctional Acetaminophen Interlayer for High Efficiency and Durability Lead-Lean Perovskite Solar Cells.

Due to the easy oxidation of Sn, which leads to form tin vacancy defects and poor perovskite film quality, caused by the rapid crystallization rate in tin-based perovskite solar cells (PSCs), their efficiency lags far behind that of lead-based PSCs. To improve the photovoltaic (PV) performance and stability of FAPEASnI-based PSCs (T-PSCs), a small amount of Pb(SCN) is introduced into a perovskite precursor as an antioxidant, and acetaminophen (ACE) with various functional groups is used to modify a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/perovskite interface. The results show that the Pb(SCN) additive and ACE interfacial modification can not only optimize energy level alignment in T-PSCs but also inhibit Sn oxidation to reduce the trap-state density, resulting in promoted carrier transport.

Whole-body linear momentum control in two-foot running jumps in male basketball players.

Running jumps that depart the ground from two feet require momenta redirection upward from initial momenta that are primarily horizontal. It is not known how each leg generates backward and upward impulses from ground reaction forces to satisfy this mechanical objective when jumping to maximize height. We examined whole-body linear momentum control strategies during these two-foot running jumps by uncovering the roles of each leg in impulse generation.

Large valley polarization and the valley-dependent Hall effect in a Janus TiTeBr monolayer.

Ferrovalley materials hold great promise for implementation of logic and memory devices in valleytronics. However, there have so far been limited ferrovalley materials exhibiting significant valley polarization and high Curie temperature (). Using first-principles calculations, we predict that the TiTeBr monolayer is a promising ferrovalley candidate.

Performance Enhancement of Tin-Based Perovskite Photodetectors through Bifunctional Cesium Fluoride Engineering.

Tin halide perovskites are rising as promising candidates for next-generation optoelectronic materials due to their good optoelectronic properties and relatively low toxicity. However, the high defect density and the easy oxidation of Sn have limited their optoelectronic performance. Herein, we report the treatment of the FASnI (formamidinium tin, FA) perovskite film by a bifunctional cesium fluoride (CsF) additive, which improves the film quality and significantly enhances the photoelectric performance.

Structure and stability of La- and hole-doped hafnia with/without epitaxial strain.

The significance of hafnia in the semiconductor industry has been amplified following the unearthing of its ferroelectric properties. We investigated the structure and electrical properties of La- and hole-doped HfOwith/without epitaxial strain by first-principles calculations. It is found that the charge compensated defect with oxygen vacancy (LaHfVO) and uncompensated defect (LaHf), compared to the undoped case, make the ferroelectric orthorhombicPca21phase (phase) more stable.

Pressure-Induced Topological Phase Transition and Large Rashba Effect in Halide Double Perovskite.

In general, hydrostatic pressure can suppress ferroelectric polarization and further reduce Rashba spin-splitting, considering the spin-orbit coupling effect. Here, we present the design of ferroelectric double perovskite CsSnSiI, which exhibits the anomalous enhancement of Rashba spin-splitting parameters by pressure-induced ferroelectric topological order. The Rashba effect is nonlinear with the decrease in polarization under pressure and reaches a maximum at the pressure-induced Weyl semimetal (WSM) state between the transition from a normal insulator (NI) to a topological insulator (TI).

Tunable and parabolic piezoelectricity in hafnia under epitaxial strain.

Piezoelectrics are a class of functional materials that have been extensively used for application in modern electro-mechanical and mechatronics technologies. The sign of longitudinal piezoelectric coefficients is typically positive but recently a few ferroelectrics, such as ferroelectric polymer poly(vinylidene fluoride) and van der Waals ferroelectric CuInPS, were experimentally found to have negative piezoelectricity. Here, using first-principles calculation and measurements, we show that the sign of the longitudinal linear piezoelectric coefficient of HfO can be tuned from positive to negative via epitaxial strain.

Strain-Induced Reversible Motion of Skyrmions at Room Temperature.

Magnetic skyrmions are topologically protected swirling spin textures with great potential for future spintronic applications. The ability to induce skyrmion motion using mechanical strain not only stimulates the exploration of exotic physics but also affords the opportunity to develop energy-efficient spintronic devices. However, the experimental realization of strain-driven skyrmion motion remains a formidable challenge.

In-plane charged antiphase boundary and 180° domain wall in a ferroelectric film.

The deterministic creation and modification of domain walls in ferroelectric films have attracted broad interest due to their unprecedented potential as the active element in non-volatile memory, logic computation and energy-harvesting technologies. However, the correlation between charged and antiphase states, and their hybridization into a single domain wall still remain elusive. Here we demonstrate the facile fabrication of antiphase boundaries in BiFeO thin films using a He-ion implantation process.

A Self-Assembled 3D/0D Quasi-Core-Shell Structure as Internal Encapsulation Layer for Stable and Efficient FAPbI Perovskite Solar Cells and Modules.

FAPbI perovskites have garnered considerable interest owing to their outstanding thermal stability, along with near-theoretical bandgap and efficiency. However, their inherent phase instability presents a substantial challenge to the long-term stability of devices. Herein, this issue through a dual-strategy of self-assembly 3D/0D quasi-core-shell structure is tackled as an internal encapsulation layer, and in situ introduction of excess PbI for surface and grain boundary defects passivating, therefore preventing moisture intrusion into FAPbI perovskite films.

Supramolecular Polyurethane "Ligaments" Enabling Room-Temperature Self-Healing Flexible Perovskite Solar Cells and Mini-Modules.

Flexible perovskite solar cells (F-PSCs) have emerged as promising alternatives to conventional silicon solar cells for applications in portable and wearable electronics. However, the mechanical stability of inherently brittle perovskite, due to residual lattice stress and ductile fracture formation, poses significant challenges to the long-term photovoltaic performance and device lifetime. In this paper, to address this issue, a dynamic "ligament" composed of supramolecular poly(dimethylsiloxane) polyurethane (DSSP-PPU) is introduced into the grain boundaries of the PSCs, facilitating the release of residual stress and softening of the grain boundaries.

Colossal Linear Magnetoelectricity in Polar Magnet Fe_{2}Mo_{3}O_{8}.

The linear magnetoelectric effect is an attractive phenomenon in condensed matters and provides indispensable technological functionalities. Here a colossal linear magnetoelectric effect with diagonal component α_{33} reaching up to ∼480  ps/m is reported in a polar magnet Fe_{2}Mo_{3}O_{8}. This effect can persist in a broad range of magnetic field (∼20  T) and is orders of magnitude larger than reported values in literature.

Mutually Tuned Dual Additive Engineering Synergistically Enhances the Photovoltaic Performance of Tin-Based Perovskite Solar Cells.

Tin-based perovskite solar cells (T-PSCs) have become the star photovoltaic products in recent years due to their low environmental toxicity and superior photovoltaic performance. However, the easy oxidation of Sn and the energy level mismatch between the perovskite film and charge transport layer limit its efficiency. In order to regulate the microstructure and photoelectric properties of tin-based perovskite films to enhance the efficiency and stability of T-PSCs, guanidinium bromide (GABr) and organic Lewis-based additive methylamine cyanate (MAOCN) are introduced into the FAPEASnI-based perovskite precursor.

Controllable Skyrmionic Phase Transition between Néel Skyrmions and Bloch Skyrmionic Bubbles in van der Waals Ferromagnet Fe GeTe.

The van der Waals (vdW) ferromagnet Fe GeTe has garnered significant research interest as a platform for skyrmionic spin configurations, that is, skyrmions and skyrmionic bubbles. However, despite extensive efforts, the origin of the Dzyaloshinskii-Moriya interaction (DMI) in Fe GeTe remains elusive, making it challenging to acquire these skyrmionic phases in a controlled manner. In this study, it is demonstrated that the Fe content in Fe GeTe has a profound effect on the crystal structure, DMI, and skyrmionic phase.

Significantly Improved Efficiency and Stability of Pure Tin-Based Perovskite Solar Cells with Bifunctional Molecules.

Tin-based perovskite solar cells (TPSCs) have become one of the most prospective photovoltaic materials due to their remarkable optoelectronic properties and relatively low toxicity. Nevertheless, the rapid crystallization of perovskites and the easy oxidization of Sn to Sn make it challenging to fabricate efficient TPSCs. In this work, a piperazine iodide (PI) material with -NH- and -NH- bifunctional groups is synthesized and introduced into the PEAFASnI-based precursor solution to tune the microstructure, charge transport, and stability of TPSCs.

All-ferroelectric implementation of reservoir computing.

Reservoir computing (RC) offers efficient temporal information processing with low training cost. All-ferroelectric implementation of RC is appealing because it can fully exploit the merits of ferroelectric memristors (e.g.

Electrical switching of ferro-rotational order in nanometre-thick 1T-TaS crystals.

Hysteretic switching of domain states is a salient characteristic of all ferroic materials and the foundation for their multifunctional applications. Ferro-rotational order is emerging as a type of ferroic order that features structural rotations, but control over state switching remains elusive due to its invariance under both time reversal and spatial inversion. Here we demonstrate electrical switching of ferro-rotational domain states in the charge-density-wave phases of nanometre-thick 1T-TaS crystals.

Antiferromagnetic to Ferrimagnetic Phase Transition and Possible Phase Coexistence in Polar Magnets (FeMn)MoO (0 ≤ ≤ 1).

In the present work, the magnetic properties of a single crystal (FeMn)MoO (0 ≤ ≤ 1) have been studied by performing extensive measurements. A detailed magnetic phase diagram is built up, in which the antiferromagnetic state dominates for ≤ 0.25 and the ferrimagnetic phase arises for ≥ 0.

Two-Dimensional Ultrahigh Unconventional Piezoelectricity Driven by Charge Screening.

In the past decade, piezoelectricity has been explored in a series of two-dimensional (2D) materials for nanoelectromechanical applications, while their piezoelectric coefficients are mostly much lower than those of prevalent piezoceramics. In this paper, we propose an unconventional approach of inducing 2D ultrahigh piezoelectricity dominated by charge screening instead of lattice distortion and show the first-principles evidence of such piezoelectricity in a series of 2D van der Waals bilayers, where the bandgap can be remarkably tuned via applying a moderate vertical pressure. Their polarizations can switch between the screened and unscreened state by a pressure-driven metal-insulator transition, which can be realized via tuning interlayer hybridization or inhomogeneous electrostatic potential by substrate layer to change the band splitting or tuning the relative energy shift between bands utilizing the vertical polarization of the substrate layer.