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Metal nanoclusters (NCs) as a new type of fluorescent material have been extensively explored because of their attractive set of features such as their ultrafine size, low toxicity, and excellent photostability. However, little progress has been made in producing water-soluble, homogeneous, and ultrabright metal NCs. In this study, gold NCs (AuNCs) with a photoluminescence quantum yield (QY) as high as 65% are synthesized in water through a simple blending route. Weak emission is observed from the 6-aza-2-thiothymine-protected AuNCs (ATT-AuNCs); however, the fluorescence intensity can be prominently enhanced by introducing l-arginine (Arg) into the capping layer. The fluorescence enhancement mechanism is systematically investigated by the measurements of ultraviolet–visible absorption spectroscopy, photoluminescence spectroscopy, fluorescence lifetime spectroscopy, transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, 1H nuclear magnetic resonance, and calculations ...

Vanadium dioxide (VO2) is a compelling candidate for next-generation electronics beyond conventional silicon-based devices due to the exhibition of a sharp metal–insulator transition. In this study, in order to realize functional VO2 film for flexible electronics, the growth of VO2 film directly on a transparent and flexible muscovite via van der Waals epitaxy is established. The heteroepitaxy and structural transition of VO2 films on muscovite are examined by a combination of high-resolution X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The unique metal–insulator transition of VO2 is further revealed with a change in electrical resistance over 103 and a more than 50% variation of optical transmittance. Furthermore, due to the nature of muscovite, the VO2/muscovite heterostructure possesses superior flexibility and optical transparence. The approach developed in this study paves an intriguing way to fabricate functional VO2 film for the applications in flexible electronics.

Exciplex systems have become increasingly important due to their good performance in devices. Considering their bipolar transporting properties, exciplex systems with strong blue fluorescence and high triplet energies could potentially be ideal hosts for fluorescence–phosphorescence hybrid (F–P) white organic light-emitting diodes (WOLEDs). Here we achieved an efficient blue exciplex system formed with a new material (4-dimesitylboryl)phenyltriphenylamine (TPAPB) and 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi), which exhibited a high photoluminescence quantum yield of 44.1%. Using only these two organic materials, a high performance blue-emitting OLED was fabricated with a maximum external quantum efficiency (EQE) of 7.0 ± 0.4%. Such high efficiency is not only among the highest results of blue fluorescent organic light-emitting diodes (OLEDs) but also indicates that high χ (fraction of excitons that can potentially radiatively decay) can be as well achieved via a TTA triplet up-conversion p...

On the basis of a D-π-A structural strategy incorporating diphenylamine as an electron-donor and 1,3,5-triazine as an electron-acceptor with a short benzene π-conjugated feature, 4-(4,6-diphenoxy-1,3,5-triazin-2-yl)-N,N-diphenylaniline (POTA), a novel blue fluorophor with high triplet energy level has been designed and synthesized to achieve high performance single-emitting-layer (single-EML) fluorescence and phosphorescence hybrid white organic light-emitting diodes (F–P hybrid WOLEDs). POTA exhibits efficient blue electrofluorescence and excellent host features for green and red phosphorescent devices. The single-EML RGB F–P hybrid WOLED based on POTA and green/red complexes shows a maximum total power efficiency of 59.8 ± 1.0 lm W–1 and a maximum total external quantum efficiency of 24.7 ± 0.7%, representing the highest efficiencies among single-EML RGB WOLEDs. Moreover, these performances are comparable with multiple-EML RGB WOLEDs even based on p-i-n structures, providing verification of the high per...

An ab initio molecular dynamics study has been performed to investigate the effects of Ag and Ni additives on Zn diffusion in steel hot-dip galvanizing. Ag−Zn, Ni−Zn, and Zn−Zn ensembles are selected to model the industry process. For the Zn−Zn ensemble, the calculated pair correlation function, first peak position, and coordination number are in good agreement with available experimental data. We examine differences in the structural and electronic properties among Ag−Zn, Ni−Zn, and Zn−Zn ensembles. For Zn self-diffusion, we obtain a diffusion constant of 2.48 × 10-9 m2/s, very close to the experimental value of 2.37 × 10-9 m2/s. The Zn diffusion constants of different ensembles increase in the following order: Ag−Zn ≈ Zn−Zn > Ni−Zn, which is in agreement with the additive effects on the thickness of coatings in galvanizing, where Ag increases the coating thickness, but Ni decreases it. Our molecular dynamics simulations reveal that the role of additives in controlling the zinc coating thickness is to a...

The DFT calculations of M-Zn12 clusters, which model the associates of Zn with 26 additive elements M in hot-dip galvanizing, have been carried out to investigate the additive effects on controlling coating thickness. A discrimination function, consisting of the calculated binding energy of clusters and the chemical shift of zinc 2p energy, is obtained which can predict the effects of additives. It has been further confirmed that an effective additive may intensely attract electronic charge from zinc and greatly grasp zinc atoms to form an associate. The zinc diffusion coefficients in the systems of various additives are estimated, by assuming that the binding energy is proportional to the diffusion activation energy and further the chemical shift is inversely proportional to the pre-exponent factor in the Arrhenius equation. The additive behaviors of six candidate elements are predicted by using the calculated diffusion coefficients. This study may assist in the design of binary and ternary additives sin...

Two types of additives in hot-dip galvanizing, effective additives Ni, V, and Ti used industrially to reduce the coating thickness of zinc−iron, and noneffective additives Mg, Sn, and Ag showing quite different behavior from the former, were studied with density functional theory calculations by using cluster models. The optimized geometric configurations, total energy, electronic density of states, and electronic charge distributions for the additive−zinc associates were obtained. Results indicated (1) the effective additives have much stronger bonding energy with zinc than the noneffective additives, (2) the electronic charges significantly shift from the zinc atoms to the Ni, V, or Ti atoms, while only a little shift to the Mg, Ag, or Sn atoms occurs, and (3) the Fermi energy level and the band gap of zinc clusters obviously change, owing to adding Ni, V, or Ti, but these effects do not occur for the second type of additives. On the basis of the calculated results, the underlying mechanism of additive ...

The synthesis, structural characterization, electrical transport, optical, and magnetic properties of a new cation-radical salt, bis(ethylenedithio)tetrathiafulvalene hexafluorophosphate, ζ-(BEDT−TTF)PF6, are reported. The X-ray structure was determined at 298 K and at 173 K. The primary difference at the two temperatures is that the PF6- anions are disordered at 298 K and ordered at 173 K. At 298 K the salt is in the triclinic space group P1 with crystallographic parameters a = 6.2793(1) A, b = 7.3680(1) A, c = 9.9006(1) A, α = 92.542(1)°, β = 93.255(1)°, γ = 98.763(1)°, vol = 451.33(1) A3. At 173 K the salt retains the same space group with parameters a = 6.2293(1) A, b = 7.2633(2) A, c = 9.8662(2) A, α = 92.898(1)°, β = 93.592(1)°, γ = 97.914(1)°, vol = 439.95(2) A3. Despite a crystal structure with uniform and segregated layers of donors and counterions, the room-temperature dc conductivity is rather low, ∼1.1 × 10-4 Ω-1 cm-1, and decreases rapidly upon cooling. Polarized reflectance measurements alo...