We report a size-dependent change in the morphology of superlattices self-assembled from monodisperse colloidal PbS nanocrystals. Superlattices large (>7 nm) nanocrystals showed strong tendency to form multiply twinned face-centered cubic with decahedral and icosahedral symmetry, exhibiting crystallographically forbidden five-fold symmetry elements. On other hand, small (<4 exhibited no twinning. To explain such dramatic difference twinning probability, we that energy nanocrystal...

Experimental and theoretical results uncover an almost perfectly linear relationship between the band gap structural aspects of g-C₃N₄, allowing tuning frequency at which g-C₃N₄ absorbs light.

The classical SiO2/Si interface, which is the basis of integrated circuit technology, prepared by thermal oxidation followed high temperature (>800 °C) annealing. Here we show that an interface synthesized between titanium dioxide (TiO2) and hydrogen-terminated silicon (H:Si) a highly efficient solar cell heterojunction can be under typical laboratory conditions from simple organometallic precursor. A thin film TiO2 grown on surface H:Si through sequence vapor deposition tetra(tert-butoxide)...

Ultrafast transient pump-probe measurements of thin ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$ perovskite films over a wide spectral range from 350 to 800 nm reveal family photoinduced bleach (PB) and absorption (PA) features unequivocally pointing the fundamentally multiband character underlying electronic structure. Excitation pump-energy dependent kinetics three long-lived PB peaks at 1.65, 2.55, 3.15 eV along with broad PA band shows involvement band-edge thermalized carriers...

We evaluated the difference between randomly packed NCs (disordered films), periodic films, and three-dimensional crystals in terms of their lattice structure interparticle spacing using time-resolved small-angle X-ray scattering (SAXS) technique. The work was performed on nanocrystal solids formed by 7 nm PbS nanocrystals capped with oleic acid. have found that faceted is ∼25% smaller as compared films solvent evaporation. showed significantly than length a fully extended molecule acid,...

Quantum dots exhibit rich and complex electronic structure that makes them ideal for studying the basic physics of semiconductors in intermediate regime between bulk materials single atoms. The remarkable nonlinear optical properties these nanostructures make strong candidates photonics applications. Here, we experimentally probe changes fine on ultrafast timescales a colloidal solution PbS quantum through their response despite extensive inhomogeneous spectral broadening. Using continuum...

The potential implementation of extreme ultraviolet (EUV) lithography into next generation device processing is bringing urgency to identify resist materials that optimize EUV lithographic performance. Inorganic/organic hybrid nanoparticles or clusters constitute a promising new class materials, with high sensitivity from the core and tunable chemistry through coordinating ligands. Development thorough mechanistic understanding solubility switching reactions in these an essential first step...

The initial stages of cobalt metal growth by atomic layer deposition are described using the precursors bis(1,4-di-tert-butyl-1,3-diazadienyl)cobalt and formic acid. Ruthenium, platinum, copper, Si(100), Si–H, SiO2, carbon-doped oxide substrates were used with a temperature 180 °C. On platinum plots thickness versus number cycles linear between 25 250 cycles, rates 0.98 Å/cycle. By contrast, on ruthenium showed delay up to before normal rate was obtained. No films observed after 50 cycles....

The self-assembly of nanoscale structures from functional nanoparticles has provided a powerful path to developing devices with emergent properties the bottom-up. Here we demonstrate that freestanding sheets self-assembled various form versatile nanomechanical resonators in megahertz frequency range. Using spatially resolved laser-interferometry measure thermal vibrational spectra and image vibration modes, show their dynamic behavior is excellent agreement linear elastic response for...

The electronic structure of single InSb quantum dots (QDs) with diameters between 3 and 7 nm was investigated using atomic force microscopy (AFM) scanning tunneling spectroscopy (STS). In this size regime, QDs show strong confinement effects which lead to discrete energy levels on both valence conduction band states. Decrease the QD increases measured gap spacing levels. Multiplets equally spaced resonance peaks are observed in spectra. There, multiplets originate from degeneracy lifting...

Abstract The structure of multiply twinned particles (MTPs) provides an example how specific crystallographic features dictate the geometric shape finite‐sized crystals. formation MTPs during colloidal synthesis can occur through at least two different pathways: 1) growth from seeds or 2) stepwise new twin boundaries on single‐crystalline (either by particle overgrowth multiparticle attachment). By utilizing in situ transmission electron microscopy, recent studies have provided real‐time...

DNA immobilization on surfaces is crucial to a number of applications. However, detailed understanding DNA/surface chemistry remains poorly documented, especially oxide surfaces, due the complexity such large molecules. This work focuses simpler molecule, 2-deoxythymidine-5-monophosphate (dTMP), which contains all chemical elements DNA. It confirms that adsorption dTMP onto OH-terminated SiO2 does not result in bond (dTMP readily washes off) and instead shows chemically adsorbs Al2O3...

Spectroscopic evidence of directed excitonic energy transfer (ET) is presented through size‐gradient CdSe/ZnS nanocrystal quantum dot (NQD) layers into an underlying Si substrate. NQD monolayers are chemically grafted on hydrogen‐terminated surfaces via a self‐assembled monolayer amine modified carboxy‐alkyl chains. Subsequent linked with short alkyldiamines. The linking approach enables accurate positioning and enhanced passivation the layers. Two different sizes NQDs (energy donors...

We report the observation of a large enhancement wavelength-dependent photocurrent in ultrathin silicon nanomembranes (SiNM) decorated with colloidal CdSe/ZnS nanocrystal quantum dots (NQDs). Back-gated, field-effect transistor structures based on 75 nm-thick SiNMs are functionalized self-assembled monolayers (SAMs) preventing surface oxidation and minimizing defect densities. NQDs drop cast active region device is measured as function excitation wavelength across NQD absorption region....

Abstract Two-dimensional transition metal dichalcogenides (TMDCs) like MoS 2 are promising candidates for various optoelectronic applications. The typical photoluminescence (PL) of monolayer is however known to suffer very low quantum yields. We demonstrate a 10-fold increase excitonic PL enabled by nonradiative energy transfer (NRET) from adjacent nanocrystal dot (NQD) films. understanding this effect facilitated our application transient absorption (TA) spectroscopy monitor the influx into...

Managing deposition of multilayered nanocrystal quantum dot (NQD) thin films is crucial for future photonic devices to maximize solar energy extraction efficiency. Solution-based NQD methods require additional protection achieve a discrete layered structure and prevent optical degradation during processing. An attractive method passivate protect overcoating with metal oxides, usually grown using atomic layer (ALD). However, significant quenching photoluminescence (PL) typically observed...

Abstract The structure of multiply twinned particles (MTPs) provides an example how specific crystallographic features dictate the geometric shape finite‐sized crystals. formation MTPs during colloidal synthesis can occur through at least two different pathways: 1) growth from seeds or 2) stepwise new twin boundaries on single‐crystalline (either by particle overgrowth multiparticle attachment). By utilizing in situ transmission electron microscopy, recent studies have provided real‐time...

Nanocrystal multilayers on different substrates are prepared via self-assembly of quantum dots at the air–liquid interface resulting in highly ordered solids which each layer can be controlled for use potential optoelectronic applications. Time-resolved photoluminescence measurements consistent with theoretical picture exciton decay stratified environment and reveal efficient energy transfer into silicon substrates. As a service to our authors readers, this journal provides supporting...

Integration of colloidal nanocrystal quantum dots (NQDs) with strongly absorbing semiconductors offers the possibility developing optoelectronic and photonic devices new functionalities. We examine process energy transfer (ET) from photoactive CdSe/ZnS core/shell NQDs into lead-halide perovskite polycrystalline films as a function distance surface using time-resolved photoluminescence (TRPL) spectroscopy. demonstrate near-field electromagnetic coupling between vastly dissimilar excitation in...

Two solution-based strategies for the preparation of partially fluorinated Si(111) surfaces from H/Si(111) were investigated using a combination scanning tunneling microscopy, X-ray photoemission spectroscopy, infrared and kinetic Monte Carlo simulations. Direct fluorination with HF (aq) produced atomically flat 11% fluorination. A two-step reaction that first methoxylated surface by in methanol then converted methoxy termination to F rough, fissured 24% The atomic-scale roughness was...

The chemical structure and thermal reactivity of recently discovered inorganic-organic hybrid resist materials are characterized using a combination in situ ex infrared (IR) spectroscopy x-ray photoemission (XPS). comprised small HfOx core capped with methacrylic acid ligands that form combined cluster, HfMAA. observed IR modes consistent the calculated predicted from previously determined crystal HfMAA-12 but also contain extrinsic hydroxyl groups. We find water content films is dependent...