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The stacking fault energy is connected to the response of crystals to deformation. Here the authors report a computational study in a model NiCo system to demonstrate the key importance of the dislocation/solute interaction for the accurate assessment of stacking fault energy in alloys beyond dilute limit.

Radiative bimolecular processes will dominate charge-carrier recombination in hybrid perovskite solar cells operating near the Shockley-Queisser limit. Here, the authors show that such processes are the inverse of absorption and increase as distribution functions sharpen towards lower temperatures.

When a molecule interacts chemically with a metal, its orbitals hybridise with metal states to form the new eigenstates of the coupled system. Here, the authors show that in addition to overlap in real space and energy, hybridizing states must fulfil a momentum-matching condition.

Understanding the deformation response of superalloys is vital to ensuring their safe operation. Here, a commercially available nickel superalloy undergoes testing at various strain rates and temperatures, revealing that twinning occurs at the interface of gamma-phase precipitates and then extends into the matrix.

Two-dimensional perovskites enable high efficiency in perovskite photovoltaics but compromise operational stability. Yaghoobi Nia et al. form two-dimensional perovskite co-crystals with neutral templating molecules, improving the stability of perovskite solar modules.

Precise modelling of solar cells devices under various conditions is essential to guide improvements in optimisation and performance of future technologies. Here, the authors present a holistic numerical model, verified with real-world data of thin-film CIGS modules, that can conduct loss analysis and predict the energy yield of thin film solar cells.

Designing photo-sensitisers with high open-circuit voltage (V_oc) is desirable to enhance the power conversion efficiency (PCE) of co-sensitized solar cells. Here, the authors employ a judiciously tailored organic sensitiser MS5 with copper electrolyte to achieve a V_oc of 1.24 V, and recorded PCE of 34.5% under ambient light.

Hot carrier solar cells offer greater conversion efficiency than single junction cells but they have yet to be demonstrated in real devices. Esmaielpour et al. show that hot carriers are harnessed from metastable valleys in III–V heterojunction devices at voltages greater than the absorber bandgap.

Medium entropy alloy CoCrNi has better mechanical properties than high entropy alloys such as CrMnFeCoNi, but why that is remains unclear. Here, the authors show that a nanostructured phase at lattice defects in CoCrNi causes its extraordinary properties, while it is magnetically frustrated and suppressed in CrMnFeCoNi.

Outdoor field testing is crucial to understand how solar cells behave under operational conditions. Here, Aydin et al. show that a lower perovskite bandgap than that calculated at laboratory standard test conditions enhances the performance of perovskite/silicon tandem cells in the field.

The intrinsic properties of atomically thin MoS₂ are believed to be strongly affected by the presence of structural defects; however, the underlying physical mechanism of such link is not fully understood. Here, the authors combine noise-current analysis with atomic force microscopy to explore the relationship between point defects and the anomalous physical properties of MoS₂ monolayers.

The hot carriers in halide perovskite nanocrystals cool much slower than those in conventional semiconductor nanocrystals due to the phonon bottleneck. Here, Li et al. demonstrate enhanced multiple exciton generation with lower threshold in intermediate-confined perovskite nanocrystals based on this effect.

Self-powered graphene photodetectors based on the photothermoelectric effect (PTE) could provide low-noise operation in the telecom and mid-infrared ranges, but their bandwidth is usually limited. Here, the authors report the realization of PTE graphene photodetectors integrated with a metamaterial perfect absorber, showing a 3-dB bandwidth above 400 GHz.

Improving the creep response of superalloys used in turbine engines is key to improving fuel efficiency and reducing carbon dioxide emissions. Here, stress-induced localized phase transformations, creating nano-laths, are found to immobilize planar defects, enhancing creep performance. Peer Review Information: Communications Materials thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editor: John Plummer. A peer review file is available.

One-dimensional molecular arrays on graphene field-effect transistors can be reversibly switched between different periodic charge states by tuning the graphene Fermi level via a back-gate electrode and by manipulating individual molecules, allowing them to function as a nanoscale shift register.

This article reviews the concept of using thermoradiative diodes for power conversion, and discusses potential applications such as night-sky power generation and waste-heat recovery.

Incorporation of the pseudo-halide anion formate during the fabrication of α-FAPbI₃ perovskite films eliminates deleterious iodide vacancies, yielding solar cell devices with a certified power conversion efficiency of 25.21 per cent and long-term operational stability.

The A-cation influence on the mechanism of slow hot carrier cooling in perovskites is controversial. Here, Man et al. resolve a debated issue regarding A-cation influence on the electronic structure of lead halide perovskites.

Manufacturing of perovskite solar cells under ambient conditions is desirable. Meng et al. show that dimethylammonium formate suppresses halide oxidation and deprotonation of organic cations, enabling air-processed inverted solar cells with 24.7% efficiency.

The interplay between reduced dimensionality and interactions in monolayer transition metal dichalcogenides has been of great research interest. Here the authors report an insulating dimer ground state in 1T-IrTe₂, driven by the combined effect of the charge density wave instability and local atomic bond formation.

Twisted double bilayer graphene is a novel van der Waals system that hosts an electric-field-tunable correlated state at half-filling. Here the authors reveal the delocalized nature of this state by scanning tunnelling microscopy and spectroscopy, suggesting an underlying mechanism of symmetry breaking driven by non-local exchange.

Here, the authors show the emergence of valley-polarized Floquet-Bloch states in 2H-WSe₂ upon below-band-gap driving using circularly polarized light.

Bandgap gradient is a promising approach to improve the open-circuit voltage in thin film solar cells. Here, authors incorporate a Cd(O,S,Se,Te) region to realize the bandgap gradient at front interface and demonstrate Cd(Se,Te) solar cells with reduced recombination and a champion efficiency of 20.03%.

The incorporation of fluorine-doped tin oxide nanoplatelets on the substrate of perovskite solar cells contributes to uniform light harvesting across different incidence angles of sunlight. The best devices show a power conversion efficiency of 26.4% (certified 25.9%), 95% of which is maintained after 1,200 hours of operation.

Defect passivation is a key concept for optimizing the performance of perovskite solar cells. This Review summarizes our understanding of defects in perovskites and highlights the most promising strategies and materials used for their passivation.

Stacking fault removal and improvement in CdTe solar efficiency is known to be correlated, yet the nature of the relationship is not well-established. Here, the authors explain the passivation process responsible for this improvement, and also elucidate the associated stacking fault removal mechanism.

Understanding excited carrier dynamics in semiconductors is central to the continued development of optoelectronic devices. Using extreme ultraviolet transient absorption spectroscopy, Zürchet al. directly and simultaneously observe ultrafast electron and hole dynamics in germanium thin films.

The local electronic structure of interface states between topologically distinct domains is imaged and controlled, allowing visualization of the interplay between strong interactions and non-trivial topology.

During carrier multiplication, high-energy free carriers in a given material relax by generation of additional electron-hole pairs. Here, the authors report evidence of carrier multiplication in multilayer MoTe₂ and WSe₂ films with up to 99% conversation efficiency.

High-resolution STM/STS visualizes the fractionalization of flat moiré bands into discrete Hofstadter subbands in moiré graphene near the predicted second magic angle, and experimentally establishes several fundamental properties of the fractal Hofstadter energy spectrum.

Dirac magnetoexcitons with non-trivial nanoscale electrodynamics are formed from the excitation of Landau levels in charge-neutral graphene. Here, the Dirac magnetoexciton dispersion is directly imaged up to 7 T via a magneto cryogenic near-field microscope.

A mismatch between quasi-Fermi level splitting and open-circuit voltage is detrimental to wide bandgap perovskite pin solar cells. Here, through theoretical and experimental approaches, the authors optimize n- and p-type interfaces to achieve open-circuit voltage of 1.29 V and T80 of 3500 h at 85 °C.

When light hits organic semiconductors, bound charge pairs, called excitons, are usually produced. Here, the authors show that in the best performing organic solar material to date, free charges, rather than excitons, are directly created by light.

A co-adsorbent is used to achieve a uniform self-assembled phosphonic acid monolayer on a textured substrate, leading to more efficient inverted perovskite solar cells.

Photoemission electron microscopy images of trap states in halide peroskites, spatially correlated with their structural and compositional factors, may help in managing power losses in optoelectronic applications. 

Localized photodoping in mixed-cation perovskites is shown to modify charge-carrier recombination and thus offer a route for more efficient light emission.

We report that fatigue cracks in pure metals can undergo intrinsic self-healing; they were observed to heal by crack flank cold welding induced by local stress state and grain boundary migration.

A complex relationship exists between microstructure development and stress field during tribological loading of a metal. Here, twinning in a high-entropy alloy is used as a model system to understand stress fields during tribological experiments, supported by molecular dynamics simulations.

Harvesting excess energy from above-band gap photons could lead to solar cells which exceed conventional efficiency limits. Liet al., study hot carrier cooling in hybrid perovskite materials with reduced dimensionality using transient absorption spectroscopy and demonstrate efficient hot-electron extraction in such systems.

The authors demonstrate electrically pumped continuous-wave operation of a SiGeSn/GeSn lasers. The devices are based on a multi-quantum-well design in a small footprint micro-disk cavity resulting in driving parameters compatible with on-chip operation.

Twisted moiré heterostructures offer a highly tunable solid-state platform for exploring fundamental condensed matter physics. Here, the authors use scanning tunnelling microscopy to investigate the local electronic structure of the gate-controlled quantum anomalous Hall insulator state in twisted monolayer–bilayer graphene.

Chemical reactions at the interface between the perovskite and hole transport layer limit the performance of inverted solar cells. Li et al. insert a p-type antimony-doped tin oxide layer that suppresses the reactions, enabling 24.8% efficiency and 500-h operational stability.

Singlet fission is an important process occurring in solar cells, however the mechanism is not well understood. Here the authors reveal intermediates during singlet fission of a non-conjugated pentacene dimer, developing a single kinetic model to describe the data over seven temporal orders of magnitude at room and cryogenic temperatures.

Earth-abundant halide perovskites are the state-of-the-art absorbers for photovoltaic devices, but their successful commercial use is hampered by phase instabilities that lead to inactivation. This Review examines how to enhance phase stability through the use of in operando analysis and the opportunities for continued material development.

Making large datasets findable, accessible, interoperable and reusable could accelerate technology development. Now, Jacobsson et al. present an approach to build an open-access database and analysis tool for perovskite solar cells.