Nano Letters最新文献

Perovskitelight-emitting diodes (LEDs) have attracted significantattention owing to their rapidly increasing external quantum efficiencies(EQEs). However, achieving bright and operationally stable perovskiteLEDs remains a great challenge. Here, we reveal that the most commonlyused surface modifier of zinc-oxide (ZnO) electron-transport layer,polyethylenimine ethoxylate (PEIE), inhibits the perovskite nucleationby inducing in situ chemical reactions of perovskite precursor components,forming thermally unstable interfacial species and reducing long-termoperational stability of resultant devices. We develop a surface-engineeringstrategy by using an ether-based polymer modifier to regulate perovskitecrystallization kinetics and simultaneously suppress ZnO-induced deprotonationduring long-term device operation. As a result, the optimized near-infrared(NIR) perovskite LEDs exhibit a maximum EQE of 24% and a peak radianceof 539 W sr^–1 m^–2, along withsignificantly enhanced operational stability. Furthermore, partialsubstitution of FA with Cs confirms the generality of this strategy,yielding bright NIR devices with an operational half-lifetime of 561h at 20 mA cm^–2.

Theatomic thickness of two-dimensional (2D) semiconductorsmakesconventional postgrowth substitutional doping highly challenging.Instead, such atomic substitution can be more effectively achieved in situ through chemical vapor deposition synthesis. However,the mechanistic details governing this growth process have remainedpoorly understood. Using V-doped monolayer MoS₂ as a modelsystem, this work elucidates its growth mechanism and doping tunabilityfacilitated by a potassium iodide (KI) promoter. A Raman spectroscopicprobe, established through correlation with scanning transmissionelectron microscopy, was developed to quantify the V dopant concentrationand distribution uniformity. Systematic growth experiments and detailedcharacterizations revealed that doping saturation levels were significantlybelow the precursor feeding ratio. This saturation phenomenon couldbe modulated by KI dosage following a Boltzmann sigmoid function,indicative of an iodide-activated doping mechanism compatible withthe edge passivation substitution (EPS) model. Our findings advancethe doping theory in low-dimensional systems and provide essentialinsights into achieving controlled heteroatom substitution in 2D semiconductors.

Metallic delafossiteoxides have drawn attention fortheir ultralowresistivity and coherent electronic transport. However, mesoscopictransport studies are hindered by the limited access to high-qualitynanoscale devices. Here, we report single-crystalline PdCoO₂ nanomembranes, enabling exploration of quasi-two-dimensional (quasi-2D)transport. Shubnikov-de Haas and angle-dependent h/e magnetoresistance oscillations under different magnetic field directionsare observed at low temperatures, from which the electron effectivemass is extracted. Beyond quantum transport, the electrical performanceof PdCoO₂ toward interconnect applications is evaluated.A nearly thickness-independent room-temperature resistivity is observedfor flakes down to 40 nm thickness. The nanomembranes exhibit a breakdowncurrent density up to 113 MA cm^–2, with excellentthermal stability and electromigration resistance. These results demonstratethat mechanically exfoliated PdCoO₂ flakes preserve thehigh crystalline and electronic quality of bulk crystals in the quasi-2Dlimit, providing a useful platform for mesoscopic transport studiesand interconnect applications.

Two-dimensional (2D) van der Waals (vdW) materials withslidingferroelectricity exhibit an enormous potential for next-generationnanodevices. Among these, 1T′-ReS₂ with an ultralowsymmetry stands out as a pivotal candidate. However, the fundamentalscientific mechanism underlying sliding ferroelectricity in 1T′-ReS₂ remains poorly understood due to the complexity of its crystalstructure. By integrating STEM, DFT calculations, and KPFM, this workresolves the correlation between AA/AB stacking and polarization in1T′-ReS₂. PFM and STEM characterizations furtherreveal that the observed ferroelectric-like PFM signals originatefrom flexoelectric-like wrinkles rather than from intrinsic ferroelectricswitching. Finally, device measurements provide evidence of slidingferroelectricity in even-layer AB-stacked ReS₂ and demonstrateits application potential.

Chemical doping of semiconductors has been widely usedto alterand enhance the photochemistry of materials. More specifically, thenature of the doping element(s) influences the inherent electronicand structural properties of semiconductors. The morphology of thesemiconductor particles can further impact the photocatalytic performanceof the materials. We report here that solo- and codoping of truncatedpyramidal BiVO₄ with phosphorus and nitrogen affects thephotoluminescence (PL) pattern and enhances the emission intensity,as observed using confocal fluorescence microscopy. The PL emissionhas been shown to increase with doping in P:BiVO₄, N:BiVO₄, and P:N:BiVO₄ by 6.8%, 10.8%, and 19.2%, respectively,relative to that of BiVO₄. Our subparticle analyses revealeda trend of corner edge > top edge > side edge. We demonstratedthatcodoping diminishes the sensitivity of PL to the particle volume,reducing the impact of structural heterogeneity in BiVO₄.

Geometric phases are fundamental to wave physics andunderpin abroad range of optical phenomena. The most prominent example, thePancharatnam–Berry (PB) phase, originates from polarizationevolution during wave propagation. In contrast, geometric phases associatedwith optical resonances and cavities remain largely unexplored. Here,we uncover the relation between the generalized PB phase and the far-fieldpolarization evolution in bound states in the continuum (BIC) cavities.We demonstrate the continuous homotopic evolution of vortex lasingmodes through geometric-phase engineering of BIC resonances. To experimentallyvalidate this concept, we realize metasurface lasers composed of titaniumdioxide hole arrays integrated with CdSe/Cd_xZn_1–xS core/shell colloidalquantum wells as the gain medium. Our results reveal a previouslyunexplored form of spin–orbit interaction in BIC cavities underoblique incidence and provide a versatile route for on-chip controlof polarization and orbital angular momentum in nanolasers.

Single-walled carbon nanotubes (SWCNTs) are promisingcandidatesfor next-generation nanoelectronics, but their atomically thin geometryand large surface area make device performance highly susceptibleto environmental degradation. Here, we fabricate field-effect transistorsbased on individual one-dimensional (1D) van der Waals heterostructuresconsisting of SWCNTs encapsulated by few-layer boron nitride nanotubes(BNNTs). We directly fabricate devices on the same individual nanotubewith and without BNNT protection, enabling a reliable comparison oftheir device performances. Statistical analysis reveals that metallicSWCNTs exhibit enhanced output currents due to the excellent electrostaticscreening of BNNTs, whereas semiconducting SWCNTs show reduced hysteresisthrough environmental isolation. Importantly, BNNTs act as a protectivebarrier against harsh environments, e.g., oxygen plasma etching, demonstratingtheir ability and potential to protect the channel during fabrication.This work suggests that coating SWCNTs with atomically smooth BNNTand forming a 1D vdW heterostructure could significantly enhance theelectrical performance and environmental robustness.

Silicon is a promisinganode for high-energy-density lithium-ionbatteries (LIBs) due to its exceptionally high theoretical capacity,yet severe volume expansion and interfacial instability hinder practicalapplication. Silicon-deposited porous carbon (SiDPC), which spatiallyconfines nanosized silicon within porous carbon frameworks, offersa distinct structural paradigm beyond conventional mechanically blendedSi–C composites. This mini-review summarizes the evolutionand engineering principles of SiDPC architectures, highlighting howstructural regulation governs electrochemical performance. Particularattention is given to the synergistic management of volume expansion,stress evolution, electron/Li⁺ transport, and solid electrolyteinterphase formation, through which SiDPC has evolved from passivebuffering to active structural regulation. Remaining challenges inscalable synthesis, electrode engineering, and practical applicationare discussed, alongside opportunities for programmable Si–Carchitectures enabled by intelligent structural design. This reviewprovides mechanistic insights and design guidelines for advancingSiDPC toward practical high-energy-density silicon anodes for LIBs.

Pathway-targetedtherapy has emerged as a promising strategy incancer treatment, yet its efficacy relies on the accurate analysisof key signaling axes in living cells. The miR-140/FEN1 signalingaxis, which is balanced in normal hepatocytes but dysregulated inhepatocellular carcinoma, represents a potential target for cancertherapy. Here, we present a DNAzyme-driven DNA nanotracker (DDN) forthe orthogonal imaging of this pathway in dual channels with highsensitivity. The nanotracker is constructed by assembling DNAzyme-poweredDNA walkers, which are responsive to miR-140 and FEN1, onto gold nanoparticles,enabling simultaneous visualization of upstream miRNA expression anddownstream enzymatic activity in living cells. Leveraging this platform,we further revealed the differential pharmacological modulations ofthe miR-140/FEN1 signaling axis by simvastatin and myricetin. In summary,the DDN serves not only as a sensitive molecular imaging probe butalso as a versatile tool for mechanistic studies, offering advancedopportunities for pathway-guided drug discovery and precision therapeutics.