Nano Letters最新文献

Air-sensitive 2D materials present fundamental challengesfor deviceintegration. Encapsulation is required to preserve intrinsic properties,yet conventional strategies require complicated fabrication workflowsand fail with thicker flakes. We demonstrate that electron-beam (e-beam)evaporated aluminum oxide (AlO_x) servesas an effective encapsulation layer and sacrificial fabrication mask,protecting sensitive flakes from air, photoresists, and chemicals.Unlike transfer-based approaches, this scalable technique requiresno stacking and enables contacts without postencapsulation etchingor harsh chemistry. Using rare-earth tritellurides (RTe₃, R = La, Er), semimetallic WTe₂, and superconductingFeTe_xSe_1–x, we show that AlO_x suppressesoxidation and preserves optical and electronic properties. We establishsubstrate-dependent optimization of encapsulation across a range offlake thicknesses, demonstrate that ultrathin AlO_x preserves WTe₂’s plasmonic response, andenhances superconducting performance in FeTe_xSe_1–x devices when employedas a mask. Thus, we overcome the longstanding trade-off between encapsulationand straightforward device fabrication in fragile quantum materials.

Plasmonic and dielectric building blocks shape the flowof lightat boundaries and interfaces. While metasurfaces that consist of plasmonicor dielectric nanophotonic elements have established a framework forshaping the far field, control over near fields remains largely unexplored.Here, we introduce disordered metasurfaces for near-field light shaping.Near-field distributions are created by engineering the interferenceof surface plasmons launched from scatterers on metallic surfaces.We demonstrate near-field metasurfaces to direct, focus, and demultiplexlight. These structures use a strip-off process, resulting in ultrasmoothmetallic surfaces suitable for efficient surface plasmon propagation.An optical imaging setup enables retrieval of the local near-fieldby mapping it into the far-field. Our concept can be generalized toarbitrary near-field distributions, permitting nanoscale routing andsorting of light based on polarization and orbital angular momentum,as well as coupling schemes to emitters and nanoscale systems in ultracompactintegrated photonic receivers and demultiplexers.

Therare-earth (RE) metal doping strategies have been investigatedfor many applications in perovskite materials. However, prior approachesto synthesizing RE-doped perovskite nanocrystals (PNCs) have predominantlyrequired harsh synthesis conditions, including an inert gas atmosphereand high temperatures. Here, we present a doping strategy using fourRE ions (La³⁺, Nd³⁺, Gd³⁺, and Er³⁺) doped into FAPbI₃ PNCs under mild conditions(50 °C) in an ambient atmosphere. Density functional theory calculationswere performed to rationalize the RE incorporation by evaluating theformation energy of possible dopant configurations within the FAPbI₃ lattice. The results demonstrated that RE ions were successfullyintroduced into interstitial sites in the FAPbI₃ latticeunder mild conditions. RE-doped FAPbI₃ PNCs were demonstratedto preserve the structure of α-FAPbI₃ PNCs, whileimproving the optical properties in colloidal and thin-film samples,delivering an enhanced power conversion efficiency of 18.65% in photovoltaicperformance together with improved stability relative to pristinePNCs.

Integrating van der Waals (vdW) devices into circuitsrequiresmetal electrodes and interconnects spanning nanometer to millimeterscales, yet mechanical deformation during electrode transfer compromisesgeometric integrity across this range. This work identifies strainlocalized at the carrier peel-front as a dominant factor influencingtransferred metal geometry. Evaluating the peel-front strain againstthickness-dependent strain tolerance of the carrier layer yields amechanics-based framework that predicts the carrier thickness forgeometry-preserving transfer. Operating within this regime preservesline continuity, edge definition, and dimensional accuracy from sub-100nm to millimeters in a single transfer. The impact of geometric preservationis evident in MoS₂ memristors with transferred electrodesas narrow as 80 nm, which improve switching durability by more thanan order of magnitude, and in field-effect transistors with a channellength of 70 nm and ultrascaled contact geometries. These resultsprovide a practical route toward scalable vdW metallization for 2Delectronics.

Cation-exchange synthesis produces monodisperse PbS quantumdots(QDs), yet its central limitation─precursor preparation anddropwise injection─is usually treated as a practical issue.Here, we recast it as sulfur chemical-potential programming; thatis, ethyl ziram (EZ) serves as a dynamic sulfur reservoir (DSR) whosethermolysis continuously evolves sulfur activity during growth. Thisreservoir couples ZnS QD seeds with reservoir-fed growth, shiftingthe reaction from externally injected templates to an internally regulatedkinetic regime, where QD size is set by the balance between seed densityand EZ-derived sulfur replenishment. The DSR route yields short-waveinfrared PbS QDs tunable from 1200 to 2200 nm, with narrow size distributions,high reproducibility, and reduced synthetic burden. Photodetectorsshow 64.7% external quantum efficiency and 5.8 × 10¹² Jones detectivity, and 640 × 512 CMOS-integrated imaging chipsexhibit a 0.04% bad-pixel rate and 3.78% photoresponse nonuniformity,validating DSR as a strategy for high-quality QD synthesis.

Despite intense research efforts, quantitative energy-resolvedmeasurements on hot carriers generated due to plasmon decay in metalnanoparticles are rare. This concerns in particular excitations belowthe Fermi level, i.e., holes. Here, we use a metallized scanning probetip to measure photocurrents from plasmonic gold nanoparticles througha monolayer of colloidal lead sulfide quantum dots. Separating outcurrent contributions from quantum dot excitons and thermionic emission,we achieve quantitative measurements on the hole excitation quantumefficiency in the gold nanoparticles in the 1.9–2.6 eV energyrange. Therefore, we combine systematic experimental bias and wavelengthvariations and a comparison with the case of aluminum with extensivemodeling. The detection scheme can be extended to electron currentsand other energy ranges by simply using quantum dots with differentenergy levels.

Limetal is a promising anode for next-generation batteries, butits high per-cycle capacity loss hinders its commercial adoption.A major contributor is the corrosion of Li during calendar aging,which accelerates the generation of degradation byproducts, such asthe solid electrolyte interphase (SEI) and isolated Li (i-Li). Here,we reveal that Li corrosion is spatially heterogeneous: five timesmore capacity is lost at the edge overhang area of the current collectorthan at the center in the coin cell form factor. To address this,we developed a selected-area insulating layer (SAIL) that preventsLi plating in the overhang, yielding a 94% reduction in corrosion-inducedcapacity loss. Electron microscopy and titration gas chromatographywere employed to visualize the morphological heterogeneity and quantifythe disconnected Li loss at the center versus the overhang. Preventingdendritic Li plating in the overhang of the current collector cantherefore substantially mitigate calendar aging-induced capacity loss.

Acidic CO₂ electroreduction (CO₂RR) preventscarbonate formation but suffers from severe competition with the hydrogenevolution reaction. Herein, a nanoreactor-structured Sn@MCHS catalystis fabricated via a ship-in-a-bottle method, synergizing the catalyticactivity of metallic Sn with the microenvironment-modulating capabilityof hollow mesoporous carbon spheres (MCHS). This mesoporous shellacts as a physical barrier, restricting proton replenishment and retainingthe in situ generated OH^–, thereby forming a localalkaline microenvironment. The nanoreactor enriches K⁺ andstabilizes *OCHO. In the acidic CO₂ reduction system, theFE of the catalyst in an H-type cell reached 90.3%, and in a flowcell it reached 95.1%. It also demonstrated excellent stability forcontinuous operation for up to 96 h. This study established nanoscaleconfinement as a powerful strategy for constructing an electrocatalyticmicroenvironment, opening up a new path for designing highly selectiveand durable electrocatalysts.