- 标题
- 摘要
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- 实验方案
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Caesium-Incorporated Triple Cation Perovskites Deliver Fully Reversible and Stable Nanoscale Voltage Response
摘要： Perovskite solar cells that incorporate small concentrations of Cs in their A-site have shown increased lifetime and improved device performance. Yet, the development of fully stable devices operating near the theoretical limit requires understanding how Cs influences perovskites’ electrical properties at the nanoscale. Here, we determine how the chemical composition of three perovskites (MAPbBr3, MAPbI3, and Cs-mixed) affects their short- and long-term voltage stabilities, with <50 nm spatial resolution. We map an anomalous irreversible electrical signature on MAPbBr3 at the mesoscale, resulting in local Voc variations of ~400 mV, and in entire grains with negative contribution to the Voc. These measurements prove the necessity of high spatial resolution mapping to elucidate the fundamental limitations of this emerging material. Conversely, we capture the fully reversible voltage response of Cs-mixed perovskites, containing small amounts of Cs, FA, and Br, demonstrating that the desired electrical output persists even at the nanoscale. The Cs-mixed material presents no spatial variation in Voc, as ion motion is restricted. Our results show that the nanoscale electrical behavior of the perovskites is intimately connected to their chemical composition and macroscopic response.
关键词： ion motion,MAPbI3,Cs-mixed perovskite,MAPbBr3,nanoscale voltage,perovskite solar cells,Kelvin probe force microscopy
更新于2025-09-23 15:23:52
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Multimodal hard x-ray imaging with resolution approaching 10 nm for studies in material science
摘要： We report multimodal scanning hard x-ray imaging with spatial resolution approaching 10 nm and its application to contemporary studies in the field of material science. The high spatial resolution is achieved by focusing hard x-rays with two crossed multilayer Laue lenses and raster-scanning a sample with respect to the nanofocusing optics. Various techniques are used to characterize and verify the achieved focus size and imaging resolution. The multimodal imaging is realized by utilizing simultaneously absorption-, phase-, and fluorescence-contrast mechanisms. The combination of high spatial resolution and multimodal imaging enables a comprehensive study of a sample on a very fine length scale. In this work, the unique multimodal imaging capability was used to investigate a mixed ionic-electronic conducting ceramic-based membrane material employed in solid oxide fuel cells and membrane separations (compound of Ce0.8Gd0.2O2?x and CoFe2O4) which revealed the existence of an emergent material phase and quantified the chemical complexity at the nanoscale.
关键词： mixed ionic-electronic conducting membrane,x-ray nanoscale imaging,multimodal imaging,high spatial resolution
更新于2025-09-23 15:23:52
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Generalized optimization method for energy conversion and storage efficiency of nanoscale flexible piezoelectric energy harvesters
摘要： The energy conversion and storage efficiency was commonly ignored in experimental studies on nanoscale flexible piezoelectric energy harvesters (PEHs). In this study, we develop a generalized theoretical method to optimize the energy conversion and storage efficiencies of nanoscale flexible PEHs. The results are validated by comparisons with experimental measurements for various ambient excitations. A simple scaling law is established to reveal the intrinsic correlation between the efficiency of energy conversion/storage and various system parameters of the PEHs. For either the energy conversion or storage circuit, the output power density may be maximized by properly designing an intrinsic normalized parameter. Furthermore, we demonstrate that an independent optimization criterion is indispensable for standard storage circuits since including a storage module into the conversion circuit redefines the electromechanical behavior of the PEH system. The results may be used as guidelines for optimizing the energy conversion and storage efficiencies of nanoscale flexible PEHs that have promising applications in harvesting biomechanical energies.
关键词： Scaling law,Optimization,Nanoscale flexible piezoelectric energy harvesters,Energy conversion,Energy storage
更新于2025-09-23 15:22:29
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Electro-thermal modeling for InxGa1-xN/GaN based quantum well heterostructures
摘要： The joint effect of the heat transfer and the electronic properties in the InGaN/GaN based quantum well (QW) heterostructures has been investigated theoretically and numerically. One-dimensional Schr?dinger equation solver coupled with Poisson equation solver and Dual-phase-lagging (DPL) heat conduction solver has been developed. The numerical results suggest that the DPL heat conduction equations capture the microscale responses caused by the phonon-electron interaction. Both effects of the polarization charge and conduction band offset between the InGaN/GaN interfaces lead to the creation of the two-dimensional electron gas (2DEG) on the lower interface of the QW. It is found that the 2DEG density at the triangular quantum well increases with increasing Indium (In) composition. This increase is the same for the conduction band offset and the electron density. As a consequence, an increase of the heat dissipation and the temperature is observed at the lower interface of the quantum well.
关键词： Indium composition,Polarization charge,Nanoscale heat transfer,Dual-phase-lagging model,InGaN heterostructure
更新于2025-09-23 15:22:29
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High-fidelity probing of the structure and heterogeneity of extracellular vesicles by resonance-enhanced atomic force microscopy infrared spectroscopy
摘要： Extracellular vesicles (EVs) are highly specialized nanoscale assemblies that deliver complex biological cargos to mediate intercellular communication. EVs are heterogeneous, and characterization of this heterogeneity is paramount to understanding EV biogenesis and activity, as well as to associating them with biological responses and pathologies. Traditional approaches to studying EV composition generally lack the resolution and/or sensitivity to characterize individual EVs, and therefore the assessment of EV heterogeneity has remained challenging. We have recently developed an atomic force microscope IR spectroscopy (AFM-IR) approach to probe the structural composition of single EVs with nanoscale resolution. Here, we provide a step-by-step procedure for our approach and show its power to reveal heterogeneity across individual EVs, within the same population of EVs and between different EV populations. Our approach is label free and able to detect lipids, proteins and nucleic acids within individual EVs. After isolation of EVs from cell culture medium, the protocol involves incubation of the EV sample on a suitable substrate, setup of the AFM-IR instrument and collection of nano-IR spectra and nano-IR images. Data acquisition and analyses can be completed within 24 h, and require only a basic knowledge of spectroscopy and chemistry. We anticipate that new understanding of EV composition and structure through AFM-IR will contribute to our biological understanding of EV biology and could find application in disease diagnosis and the development of EV therapies.
关键词： spectroscopy,heterogeneity,nanoscale characterization,AFM-IR,extracellular vesicles
更新于2025-09-23 15:22:29
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Modeling the Compressive Behavior of Anisotropic, Nanometer-Scale Structured Silica
摘要： Recently, large plastic deformations were observed during compression testing of biotemplated, anisotropic, and hierarchically structured silica monoliths. Based on the material’s nanometer-scale structuring, a dynamic model is devised in which parallel silica struts are compressed, and sheared in longitudinal direction. The resulting interfacial shear forces lead to successive plastic deformations during cyclic loading with incrementally increasing forces, matching observations by mechanical testing. The authors report on the physical parameter values obtained from fitting model curves to measured ones, their relation to prior structural observations, and their utility to tailor the intricate mechanical behavior of this novel material.
关键词： simulation,deformation,dynamic,fracture,nanoscale,silica,brittle
更新于2025-09-23 15:22:29
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Atomic Force Microscopy in Molecular and Cell Biology || Assessment of Pathological or Drug-Dependent Changes in Cell Membrane Morphology and Cell Biomechanical Properties by Atomic Force Microscopy
摘要： Identification of the nanoscale changes that take place in cell membrane (CM) morphology or cell biomechanical properties (CBPs) in disease states or in response to drug treatment enable for a better understanding of the effects of the drugs on disease pathogenesis and recovery. CM proteins and CBPs have a crucial role in the regulation of many physiological and pathological processes. Direct assessment of the CM and CBPs is therefore useful not only for a better appreciation of cell structure but also for a better understanding of cell pathophysiology. Atomic force microscopy (AFM) is a technique that can be employed to assess CM structure and CBPs at the nanometer scale. In the first part of this chapter, we describe the principles of AFM and appraise its value in the assessment of CM morphology and CBPs. In the second part, we review examples of disease- or drug- dependent changes in CM morphology and CBPs that have been elucidated using AFM.
关键词： Nanoscale,Atomic force microscopy,Cell membrane
更新于2025-09-23 15:21:21
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Nanoscale spatial mapping of charge carrier dynamics in perovskite solar cells
摘要： Charge carrier dynamics and behaviors are key parameters and need to be mapped at the nanoscale in order to search for correct materials for high-performance solar cells. Unfortunately, currently, there are no existing tools or capabilities that can simultaneously map charge carrier dynamics at nanometer range in solar cells. Here we use a Transient Photo-response AFM (TP-AFM) to map for the first time apparent carrier recombination lifetime (τr), transport time (τt) and diffusion length (LD) in hybrid perovskites solar cells. These spatially resolved parameters reveal substantial variations at grain boundaries (GBs) τr, τt and LD at GBs broaden the performance of these state-of-the-art mixed cation perovskites. Detail analysis of these parameters allow us to conclude that reduced density of trap states and recombination in mixed cation perovskites at GBs and its surrounding locations (extending to several nanometers into the grain interior) implies less ion migration. This first of its kind experimental realization of nanoscale mapping of charge carrier dynamics in photovoltaic materials can be used for applications in other optoelectronic devices.
关键词： Perovskites,Nanoscale mapping and ion migration,Grain boundary,Charge carrier dynamics
更新于2025-09-23 15:21:01
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Nanometer control in plasmonic systems through discrete layer-by-layer macrocyclea??cation deposition
摘要： In this work, we demonstrate that coordination interactions between Fe3+ and cucurbit[7]uril (CB[7]) can be utilised to build up defined nanoscale spacing layers in metallic nanosystems. We begin by characterising the layer-by-layer deposition of CB[7] and FeCl3?6H2O coordination layers through the use of a Quartz-Crystal Microbalance (QCM) and contact angle measurements. We then apply this layered structure to accurately control the spacing, and thus optical properties, of gold nanoparticles in a Nanoparticle-on-Mirror (NPoM) structure, which is demonstrated via normalising plasmon resonance spectroscopy.
关键词： nanoscale,Fe3+,plasmonic,coordination,cucurbit[7]uril
更新于2025-09-23 15:21:01
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Dielectric Properties of Pulsed Laser Deposited Nanoscale CeNi5 Thin Films
摘要： Dielectric properties of pulsed laser deposited, nanoscale CeNi5 alloy layers, on glass or SiO2 substrate are described using the complex dielectric function. The UV–Vis–NIR spectral behavior of this function is studied separately for its real part ε1 (the dielectric constant or dielectric permittivity), and for its imaginary part ε2 (the dielectric loss function). The layers were obtained from grinded CeNi5 bulk powder using short, modulated laser pulses. The absolute reflectance of the obtained nanoscale alloy layers was measured at the 632.8 nm wavelength of a liquid nitrogen cooled and stabilized He–Ne source. This value was further used to renormalize the relative differential reflectance spectroscopy measurements performed in the UV?Vis?NIR domain. The obtained absolute reflectance spectra were processed using the Kramers–Kr?nig formalism, so that the real and imaginary parts of the complex dielectric function could be computationally determined, also leading to the calculation of the electron loss functions –Im ε–1 and –Im(1 + ε)–1. The behavior of these functions near the spectral inflexion points was determined using appropriate theoretical considerations. The variation of the dielectric functions was explained, electron density of states and the shape of the energy bands were inferred. This study reveals the layer thickness and deposition substrate dependent optical and electrical properties of the produced nanoscale CeNi5 structures.
关键词： dielectric constant,nanoscale CeNi5 thin films,dielectric loss function,pulsed laser deposition,electron energy band structures
更新于2025-09-23 15:21:01