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Tensile-strained Mxene/carbon nanotube (CNT) porous microspheres were developed as an electrocatalyst for the lithium polysulfide (LiPS) redoxr eaction. The internal stress on the surface results in lattice distortion with expanding TiÀTi bonds,e ndowing the Mxene nanosheet with abundant active sites and regulating the d-band center of Ti atoms upshifted closer to the Fermi level, leading to strengthened LiPS adsorbability and accelerated catalytic conversion. The macroporous framework offers uniformed sulfur distribution, potent sulfur immobilization, and large surface area. The composite interwoven by CNT tentacle enhances conductivity and prevents the restacking of Mxene sheets.This combination of tensile strain effect and hierarchical architecture design results in smooth and favorable trapping-diffusion-conversion of LiPS on the interface.T he Li-S battery exhibits an initial capacity of 1451 mAh g À1 at 0.2 C, rate capability up to 8C,and prolonged cycle life.

Bismuth-based double perovskite Cs2AgBiBr6 is regarded as a potential candidate for low-toxicity, high-stability perovskite solar cells. However, its performance is far from satisfactory. Albeit being an indirect bandgap semiconductor, we observe bright emission with large bimolecular recombination coefficient (reaching 4.5 ± 0.1 × 10−11 cm3 s−1) and low charge carrier mobility (around 0.05 cm2 s−1 V−1). Besides intermediate Fröhlich couplings present in both Pb-based perovskites and Cs2AgBiBr6, we uncover evidence of strong deformation potential by acoustic phonons in the latter through transient reflection, time-resolved terahertz measurements, and density functional theory calculations. The Fröhlich and deformation potentials synergistically lead to ultrafast self-trapping of free carriers forming polarons highly localized on a few units of the lattice within a few picoseconds, which also breaks down the electronic band picture, leading to efficient radiative recombination. The strong self-trapping in Cs2AgBiBr6 could impose intrinsic limitations for its application in photovoltaics.

The optoelectronic properties of lead halide perovskites strongly depend on their underlying crystal symmetries and dynamics, sometimes exhibiting a dual photoluminescence (PL) emission via Rashba-like effects. Here we exploit spin-and temperature-dependent PL to study single crystal APbBr3 (A= Cs and methylammonium; CH3NH3) to evaluate peak energy, intensity and linewidth evolutions of the dual emissions. Both materials are identified to have two temperature regimesabove and below approximately 100 Kbeing governed by different carrier scattering and radiative recombination dynamics. With increasing temperature, high-energy optical phonons (>11 meV) are found to drive energy splitting of the dual bands and electron-longitudinal-optical-phonon coupling dominates the linewidth broadening, with a stronger coupling constant inferred in CsPbBr3 for the spin-split indirect bands (78 meV) compared to the direct one (54 meV). We find the unusual thermal evolution of all-inorganic CsPbBr3 and hybrid MAPbBr3 perovskites are comparablesuggesting A-site independence and dominance of dynamic spin-splitting effectsand are best understood within a framework which accounts for bulk Rashba-like effects. The interest for solution-processable lead halide perovskites within efficient solar cells 1,2 stems from their promising optoelectronic response to the solar photons and high tolerance to defects 3,4. This family of semiconductors are increasingly being considered as "soft" solid-state materials 5-7 , whereby the fate of photo-generated charges primarily rely on the fundamental carrier-lattice interaction dynamics. For instance, polaron formationvia carrier-longitudinaloptical-phonon (Fröhlich) interactionswithin the lattice has been linked to several favourable qualities, like long carrier lifetimes and diffusion lengths 8-10. Recent indications of spin splitting and indirect tail state formation in lead halide perovskites 11-16 due to Rashba-like effects 17 motivate a reconsideration of how electron-phonon coupling can exist within its perturbed electronic band structure. Universally, for the application of any polar metal halide perovskite, the properties of the free charge carriers and phonon scattering mechanisms are central to its optoelectronic performance at room temperature (RT).

Lithium-sulfur (Li-S) batteries present one of the most promising energy storage systems owing to their high energy density and low cost. However, the commercialization of Li-S batteries is still hindered by several technical issues; the notorious polysulfide shuttling and sluggish sulfur conversion kinetics. In this work, unique hierarchical Fe 3-x C@C hollow microspheres as an advanced sulfur immobilizer and promoter for enabling high-efficiency Li-S batteries is developed. The porous hollow architecture not only accommodates the volume variation upon the lithiation-delithiation processes, but also exposes vast active interfaces for facilitated sulfur redox reactions. Meanwhile, the mesoporous carbon coating establishes a highly conductive network for fast electron transportation. More importantly, the defective Fe 3-x C nanosized subunits impose strong LiPS adsorption and catalyzation, enabling fast and durable sulfur electrochemistry. Attributed to these structural superiorities, the obtained sulfur electrodes exhibit excellent electrochemical performance, i.e., high areal capacity of 5.6 mAh cm -2 , rate capability up to 5 C, and stable cycling over 1000 cycles with a low capacity fading rate of 0.04% per cycle at 1 C, demonstrating great promise in the development of practical Li-S batteries.

Electrical manipulation of skyrmions attracts considerable attention for its rich physics and promising applications. To date, such a manipulation is realized mainly via spin-polarized current based on spin-transfer torque or spin-orbital torque effect. However, this scheme is energy-consuming and may produce massive Joule heating. To reduce energy dissipation and risk of heightened temperatures of skyrmion-based devices, an effective solution is to use electric field instead of current as stimulus. Here, we realize an electric-field manipulation of skyrmions in a nanostructured ferromagnetic/ferroelectrical heterostructure at room temperature via an inverse magneto-mechanical effect. Intriguingly, such a manipulation is non-volatile and exhibits a multi-state feature. Numerical simulations indicate that the electric-field manipulation of skyrmions originates from strain-mediated modification of effective magnetic anisotropy and Dzyaloshinskii-Moriya interaction. Our results open a direction for constructing low-energy-dissipation, non-volatile, and multi-state skyrmion-based spintronic devices.

Nowadays the development of machine vision is oriented toward real-time applications such as autonomous driving. This demands a hardware solution with low latency, high energy efficiency, and good reliability. Here, we demonstrate a robust and self-powered in-sensor computing paradigm with a ferroelectric photosensor network (FE-PS-NET). The FE-PS-NET, constituted by ferroelectric photosensors (FE-PSs) with tunable photoresponsivities, is capable of simultaneously capturing and processing images. In each FE-PS, self-powered photovoltaic responses, modulated by remanent polarization of an epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 layer, show not only multiple nonvolatile levels but also sign reversibility, enabling the representation of a signed weight in a single device and hence reducing the hardware overhead for network construction. With multiple FE-PSs wired together, the FE-PS-NET acts on its own as an artificial neural network. In situ multiply-accumulate operation between an input image and a stored photoresponsivity matrix is demonstrated in the FE-PS-NET. Moreover, the FE-PS-NET is faultlessly competent for real-time image processing functionalities, including binary classification between ‘X’ and ‘T’ patterns with 100% accuracy and edge detection for an arrow sign with an F-Measure of 1 (under 365 nm ultraviolet light). This study highlights the great potential of ferroelectric photovoltaics as the hardware basis of real-time machine vision.

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