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The open-circuit voltage ( V OC ) deficit in perovskite solar cells is greater in wide-bandgap (over 1.7 eV) cells than in perovskites of roughly 1.5 eV (refs.  1 , 2 ). Quasi-Fermi-level-splitting measurements show V OC -limiting recombination at the electron-transport-layer contact 3 – 5 . This, we find, stems from inhomogeneous surface potential and poor perovskite–electron transport layer energetic alignment. Common monoammonium surface treatments fail to address this; as an alternative, we introduce diammonium molecules to modify perovskite surface states and achieve a more uniform spatial distribution of surface potential. Using 1,3-propane diammonium, quasi-Fermi-level splitting increases by 90 meV, enabling 1.79 eV perovskite solar cells with a certified 1.33 V V OC and over 19% power conversion efficiency (PCE). Incorporating this layer into a monolithic all-perovskite tandem, we report a record V OC of 2.19 V (89% of the detailed balance V OC limit) and over 27% PCE (26.3% certified quasi-steady state). These tandems retained more than 86% of their initial PCE after 500 h of operation. Because open-circuit voltage deficit is greater in wide-bandgap perovskite solar cells, the authors introduce diammonium molecules to modify perovskite surface states and achieve a more uniform spatial distribution of surface potential, enabling record voltage all-perovskite tandem solar cells.

In recent years, the concept of entropy stabilization of crystal structures in oxide systems has led to an increased research activity in the field of “high entropy oxides”. These compounds comprise the incorporation of multiple metal cations into single-phase crystal structures and interactions among the various metal cations leading to interesting novel and unexpected properties. Here, we report on the reversible lithium storage properties of the high entropy oxides, the underlying mechanisms governing these properties, and the influence of entropy stabilization on the electrochemical behavior. It is found that the stabilization effect of entropy brings significant benefits for the storage capacity retention of high entropy oxides and greatly improves the cycling stability. Additionally, it is observed that the electrochemical behavior of the high entropy oxides depends on each of the metal cations present, thus providing the opportunity to tailor the electrochemical properties by simply changing the elemental composition. High entropy oxides provide a new strategy toward materials design by stabilizing single-phase crystal structures composed of multiple cations. Here, the authors apply this concept to the development of conversion-type electrode materials for lithium-ion storage and show the underlying mechanism.

Electrocatalytic water splitting is a promising route for sustainable hydrogen production. However, the high overpotential of the anodic oxygen evolution reaction poses significant challenge. SrIrO 3 -based perovskite-type catalysts have shown great potential for acidic oxygen evolution reaction, but the origins of their high activity are still unclear. Herein, we develop a Co-doped SrIrO 3 system to enhance oxygen evolution reaction activity and elucidate the origin of catalytic activity. In situ experiments reveal Co activates surface lattice oxygen, rapidly exposing IrO x active sites, while bulk Co doping optimizes the adsorbate binding energy of IrO x . The Co-doped SrIrO 3 demonstrates high oxygen evolution reaction electrocatalytic activity, markedly surpassing the commercial IrO 2 catalysts in both conventional electrolyzer and proton exchange membrane water electrolyzer. SrIrO 3 -based catalyst is a promising candidate for acidic oxygen evolution reaction (OER), but the active sites and factors responsible for its effectiveness remain ambiguous. Here, the authors reveal that dynamic dissolution of Co in Co-SrIrO 3 leads to the formation of unsaturated IrOx, enabling high-efficiency OER.

MXenes are an emerging family of highly-conductive 2D materials which have demonstrated state-of-the-art performance in electromagnetic interference shielding, chemical sensing, and energy storage. To further improve performance, there is a need to increase MXenes’ electronic conductivity. Tailoring the MXene surface chemistry could achieve this goal, as density functional theory predicts that surface terminations strongly influence MXenes' Fermi level density of states and thereby MXenes’ electronic conductivity. Here, we directly correlate MXene surface de-functionalization with increased electronic conductivity through in situ vacuum annealing, electrical biasing, and spectroscopic analysis within the transmission electron microscope. Furthermore, we show that intercalation can induce transitions between metallic and semiconductor-like transport (transitions from a positive to negative temperature-dependence of resistance) through inter-flake effects. These findings lay the groundwork for intercalation- and termination-engineered MXenes, which promise improved electronic conductivity and could lead to the realization of semiconducting, magnetic, and topologically insulating MXenes. Two-dimensional transition metal carbides and nitrides (MXenes) have emerged as highly conductive and stable materials, of promise for electronic applications. Here, the authors use in situ electric biasing and transmission electron microscopy to investigate the effect of surface termination and intercalation on electronic properties.

The synthesis of 2D materials with no analogous bulk layered allotropes promises a substantial breadth of physical and chemical properties through the diverse structural options afforded by substrate-dependent epitaxy. However, despite the joint theoretical and experimental efforts to guide materials discovery, successful demonstrations of synthetic 2D materials have been rare. The recent synthesis of 2D boron polymorphs (that is, borophene) provides a notable example of such success. In this Perspective, we discuss recent progress and future opportunities for borophene research. Borophene combines unique mechanical properties with anisotropic metallicity, which complements the canon of conventional 2D materials. The multi-centre characteristics of boron–boron bonding lead to the formation of configurationally varied, vacancy-mediated structural motifs, providing unprecedented diversity in a mono-elemental 2D system with potential for electronic applications, chemical functionalization, materials synthesis and complex heterostructures. With its foundations in computationally guided synthesis, borophene can serve as a prototype for ongoing efforts to discover and exploit synthetic 2D materials.

Two-dimensional (2D) semiconductors, such as transition metal dichalcogenides, provide an opportunity for beyond-silicon exploration. However, the lab to fab transition of 2D semiconductors is still in its preliminary stages, and it has been challenging to meet manufacturing standards of stability and repeatability. Thus, there is a natural eagerness to grow wafer-level, high-quality films with industrially acceptable scale–cost–performance metrics. Here we report an improved chemical vapour deposition synthesis method in which the controlled release of precursors and substrates predeposited with amorphous Al2O3 ensure the uniform synthesis of monolayer MoS2 as large as 12 inches while also enabling fast and non-toxic growth to reduce manufacturing costs. Transistor arrays were fabricated to further confirm the high quality of the film and its integrated circuit application potential. This work achieves the co-optimization of scale–cost–performance metrics and lays the foundation for advancing the integration of 2D semiconductors in industry-standard pilot lines.A route to the rapid and batch production of 12 inch MoS2 monolayers is reported, which shows a synergistic optimization of scale–cost–performance metrics for a transition from lab to fab.

Researches on flexible thermoelectric materials usually focus on conducting polymers and conducting polymer-based composites; however, it is a great challenge to obtain high thermoelectric properties comparable to inorganic counterparts. Here, we report an n-type Ag 2 Se film on flexible nylon membrane with an ultrahigh power factor ~987.4 ± 104.1 μWm −1 K −2 at 300 K and an excellent flexibility (93% of the original electrical conductivity retention after 1000 bending cycles around a 8-mm diameter rod). The flexibility is attributed to a synergetic effect of the nylon membrane and the Ag 2 Se film intertwined with numerous high-aspect-ratio Ag 2 Se grains. A thermoelectric prototype composed of 4-leg of the Ag 2 Se film generates a voltage and a maximum power of 18 mV and 460 nW, respectively, at a temperature difference of 30 K. This work opens opportunities of searching for high performance thermoelectric film for flexible thermoelectric devices. Although flexible thermoelectric materials based on conducting polymers are attractive for energy harvesting, their performance is inferior to their inorganic counterparts. Here, the authors present a facile method to deliver inorganic nanowire films with high power factor and flexibility.

Synthesis of atomically precise zigzag edges in graphene nanoribbons is demonstrated using a bottom-up strategy based on surface-assisted arrangement and reaction of precursor monomers; these nanoribbons have edge-localized states with large energy splittings. Graphene on the ragged edge Graphene nanoribbons with zigzag edges are predicted to host spin-polarized electronic edge states that would make them suitable as elements for graphene-based spintronics applications. The production of nanoribbons with 'zigzag', rather than the more familiar 'armchair' edges, remains a major challenge, in part because of the instability of such edge configurations. This paper reports an elegant bottom-up strategy for the production of zigzag-edged graphene nanoribbons, based on the surface-assisted arrangement and reaction of precursor monomers. The authors also present evidence of the predicted spin-polarized edge states obtained using scanning tunnelling microscopy. Graphene-based nanostructures exhibit electronic properties that are not present in extended graphene. For example, quantum confinement in carbon nanotubes and armchair graphene nanoribbons leads to the opening of substantial electronic bandgaps that are directly linked to their structural boundary conditions 1 , 2 . Nanostructures with zigzag edges are expected to host spin-polarized electronic edge states and can thus serve as key elements for graphene-based spintronics 3 . The edge states of zigzag graphene nanoribbons (ZGNRs) are predicted to couple ferromagnetically along the edge and antiferromagnetically between the edges 4 , but direct observation of spin-polarized edge states for zigzag edge topologies—including ZGNRs—has not yet been achieved owing to the limited precision of current top-down approaches 5 , 6 , 7 , 8 , 9 , 10 . Here we describe the bottom-up synthesis of ZGNRs through surface-assisted polymerization and cyclodehydrogenation of specifically designed precursor monomers to yield atomically precise zigzag edges. Using scanning tunnelling spectroscopy we show the existence of edge-localized states with large energy splittings. We expect that the availability of ZGNRs will enable the characterization of their predicted spin-related properties, such as spin confinement 11 and filtering 12 , 13 , and will ultimately add the spin degree of freedom to graphene-based circuitry.

Electrostatic adsorption is an important complement to the mechanical filtration for high-efficiency air filtering. However, the electrostatic charge decays with time, especially in humid conditions. In this work, a self-charging air filter is presented to capture airborne particles in an efficient and long-lasting manner without the need of external power sources. Leveraging the triboelectric effect between the electrospun poly(vinylidene fluoride) nanofiber film and nylon fabric, the self-charging air filter-based mask excited by breathing can continuously replenish electrostatic charges. As a result, its effective lifespan is up to 60 hours (including 30 hours of wearing), with a minimum filtration efficiency of 95.8% for 0.3-μm particles. The filtration efficiency and lifespan are significantly higher than those of a commercial surgical mask. Furthermore, we uncover the quantitative relation between filtration efficiency and surface electrostatic potential. This work provides an effective strategy to significantly prolong the electrostatic adsorption efficacy for high-performance air-filtering masks. The decay of electrostatic charges largely reduces the protective efficacy of electret masks. Here, the authors report a triboelectrification-based self-charging electrostatic face mask with high airborne particle capture efficiency and prolonged stability.

Ferroelectric materials are fascinating for their non-volatile switchable electric polarizations induced by the spontaneous inversion-symmetry breaking. However, in all of the conventional ferroelectric compounds, at least two constituent ions are required to support the polarization switching 1 , 2 . Here, we report the observation of a single-element ferroelectric state in a black phosphorus-like bismuth layer 3 , in which the ordered charge transfer and the regular atom distortion between sublattices happen simultaneously. Instead of a homogenous orbital configuration that ordinarily occurs in elementary substances, we found the Bi atoms in a black phosphorous-like Bi monolayer maintain a weak and anisotropic s p orbital hybridization, giving rise to the inversion-symmetry-broken buckled structure accompanied with charge redistribution in the unit cell. As a result, the in-plane electric polarization emerges in the Bi monolayer. Using the in-plane electric field produced by scanning probe microscopy, ferroelectric switching is further visualized experimentally. Owing to the conjugative locking between the charge transfer and atom displacement, we also observe the anomalous electric potential profile at the 180° tail-to-tail domain wall induced by competition between the electronic structure and electric polarization. This emergent single-element ferroelectricity broadens the mechanism of ferroelectrics and may enrich the applications of ferroelectronics in the future. A single-element ferroelectric state is observed in a black phosphorus-like bismuth layer, in which the ordered charge transfer and the regular atom distortion between sublattices happen simultaneously and ferroelectric switching is further visualized experimentally.