Search results for "bonding"
showing 10 items of 996 documents
Non-linear optical study of hierarchical 3D Al doped ZnO nanosheet arrays deposited by successive ionic adsorption and reaction method
2020
Abstract Successive ionic layer adsorption and reaction (SILAR) method is based on the adsorption and reaction of the ions in the cationic solution and the ionic solution, respectively. This method is simple, inexpensive, large-scale deposition, effective way for deposition on 3D substrates, low-temperature process and represents an easy way for the preparation of doped, composite and heterojunction materials. To take advantage of this method and the ZnO nanostructures, various parameters have been optimized. Undoped and Aluminum (Al) doped ZnO nanostructures were prepared by the SILAR technique. The characterization of the nanostructures prepared was carried out using X-ray diffraction (XR…
Temperature Effect of Ionic Transition Metal Complex Light-Emitting Electrochemical Cells
2013
ABSTRACTLight-Emitting Electrochemical Cells (LECs) consist of solution processable ionic light-emitting materials and use air stable electrodes. Their operational mechanism relies on both ionic and electronic conduction. The dynamic behavior is primarily determined by the ionic conductivity. Here, we demonstrate that with increasing temperature the LECs turn-on faster yet without decreasing the efficiency. This is due to the activation energy of ionic transport and the temperature independent photoluminescence quantum yields.
Exploring the effect of the cyclometallating ligand in 2-(pyridine-2-yl)benzo[d]thiazole-containing iridium(III) complexes for stable light-emitting …
2018
The preparation and characterization of a series of iridium(III) ionic transition-metal complexes for application in light-emitting electrochemical cells (LECs) are reported. The complexes are of the type [Ir(C^N)2(N^N)][PF6] in which C^N is one of the cyclometallating ligands 2-(3-(tert-butyl)phenyl)pyridine (tppy), 2-phenylbenzo[d]thiazole (pbtz), 1-phenyl-1H-pyrazole (ppz) and 1-phenylisoquninoline (piq), and N^N is 2-(pyridine-2-yl)benzo[d]thiazole (btzpy). The variation in the C^N ligands allows the HOMO energy level to be tuned, leading to HOMO–LUMO gaps in the range 2.76–3.01 eV and values of Eox1/2 of 0.81–1.11 V. In solution, the complexes are orange to deep-red emitters (λmax in t…
Angstrom-Size Defect Creation and Ionic Transport through Pores in Single-Layer MoS2
2018
Atomic-defect engineering in thin membranes provides opportunities for ionic and molecular filtration and analysis. While molecular-dynamics (MD) calculations have been used to model conductance through atomic vacancies, corresponding experiments are lacking. We create sub-nanometer vacancies in suspended single-layer molybdenum disulfide (MoS2) via Ga+ ion irradiation, producing membranes containing ∼300 to 1200 pores with average and maximum diameters of ∼0.5 and ∼1 nm, respectively. Vacancies exhibit missing Mo and S atoms, as shown by aberration-corrected scanning transmission electron microscopy (AC-STEM). The longitudinal acoustic band and defect-related photoluminescence were observe…
Surface modification of all-inorganic lead halide perovskite nanocrystals
2021
Abstract Newly emerged all-inorganic lead halide perovskite nanocrystals have shown unprecedented optical properties for a variety of display applications. Their superior optical properties over traditional semiconductor nanocrystals have opened a new paradigm in luminescent materials research. Because of their defect tolerance, the photoluminescent quantum yield of lead halide perovskite nanocrystals can reach near-unity. However, the ionic character of these nanocrystals causes extreme lability, which deteriorates its structural and optical properties. Moreover, the binding ability of surface ligands are quite weak and thus easily desorb during conventional purification techniques. Despit…
Stable and Efficient Solid-State Light-Emitting Electrochemical Cells Based on a Series of Hydrophobic Iridium Complexes
2011
Light-emitting electrochemical cells (LECs) based on ionic transition-metal complexes (iTMCs) exhibiting high efficiency, short turn-on time, and long stability have recently been presented. Furthermore, LECs emitting in the full range of the visible spectrum including white light have been reported. However, all these achievements were obtained individually, not simultaneously, using in each case a different iTMC. In this work, device stability is maintained by employing intrinsically stable ionic iridium complexes, while increasing the complex and the device quantum yields for exciton-to-photon conversion. This is done by sequentially modifying the archetype ionic iridium complex [Ir(ppy)…
High-resolution microwave spectroscopy on trapped ion clouds
1994
Ion traps are particular usefully devices for precision spectroscopy on ionic ground states in the microwave domain. Although ultimate precision is achieved only with laser-cooled single ions, in many cases the precision obtained using large uncooled clouds of ions is sufficient for many requirements in atomic physics. The stronger signal in this case makes possible experiments on forbidden transitions or on systems with complex spectra and many substates. Recent examples of laser-microwave double resonance spectra on Pb+ and Eu+ are presented along with attempts to laser-cool a large ion cloud in order to reduce uncertainties from the second-order Doppler effect.
Enhanced operational stability through interfacial modification by active encapsulation of perovskite solar cells
2020
Encapsulates are, in general, the passive components of any photovoltaic device that provides the required shielding from the externally stimulated degradation. Here we provide comprehensive physical insight depicting a rather non-trivial active nature, in contrast to the supposedly passive, atomic layer deposition (ALD) grown Al2O3 encapsulate layer on the hybrid perovskite [(FA0.83MA0.17)0.95Cs0.05PbI2.5Br0.5] photovoltaic device having the configuration: glass/FTO/SnO2/perovskite/spiro-OMeTAD/Au/(±) Al2O3. By combining various electrical characterization techniques, our experimental observations indicate that the ALD chemistry produces considerable enhancement of the electronic conductiv…
Non-ideal mixing behavior in dibutyl phosphate-propylamine binary liquids: Dielectric and nuclear magnetic resonance investigations
2021
Abstract Owing to the amphiphilic nature of their constituent molecules, binary mixtures of pure liquid surfactants are usually characterized by enhanced nano-segregation and thus can exhibit interesting transport properties and complex macroscopic behavior. In this ambit it was recently shown by Turco Liveri et al. (J. Mol. Liq. 263 (2018) 274–281) at room temperature that mixtures of short aliphatic chains compounds, such as dibutyl phosphate (DBP) and n-propylamine (PA) liquids, due to their ability to allow for phosphate-to-amine proton transfer, display ionic liquid–like behavior with composition-dependent enhanced conductivity, viscosity, and magnetically-induced birefringence. To und…
Metal–organic covalent network chemical vapor deposition for gas separation
2016
The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal–organic covalent network (MOCN) layers. The resulting hyper-thin and flexible MOCN layers exhibit outstanding gas-separation performances for multiple gas pairs.