Search results for "Volt"
showing 10 items of 2187 documents
Density of States characterization of TiO2 films deposited by Pulsed Laser Deposition for Heterojunction solar cells
2021
The application of titanium dioxide (TiO2) in the photovoltaic field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact. For modeling-based optimization of such contact, knowledge of the titanium oxide defect density of states is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band …
Empowering Photovoltaics with Smart Light Management Technologies
2021
The daily Sun supplies the continents of the Earth with four times more energy than humanity consumes in a year. This enormous potential of solar energy to generate clean energy is therefore driving great efforts to replace conventional and unsustainable fossil fuel consumption that damages our climate and our environment. Solar photovoltaic (PV) is emerging as the fastest growing renewable energy technology in the world, yet its share to the electricity production currently is less than 3%. While coal and gas remain key to electricity production, the climate crisis demands a fast transition to a carbon-neutral energy system. In the year 2019, the PV industry produced solar panels with a ca…
Acid versus base peptization of mesoporous nanocrystalline TiO2 films: functional studies in dye sensitized solar cells
2005
We report an analysis of the influence of acid/base conditions employed in the synthesis of TiO2 nanoparticles upon the performance of dye sensitised photoelectrochemical solar cells fabricated from these particles. The functional properties of the TiO2 nanoparticles in these devices are investigated by potential step chronoamperometry, transient laser spectroscopy, and photovoltaic device characterisation. We find that base peptization conditions employed in the sol–gel fabrication of the TiO2 nanoparticles result in a reduction in film electron density under negative applied bias, correlated with slower interfacial recombination losses and a higher device open circuit voltage.
Electrochemical characterization of praseodymia doped zircon. Catalytic effect on the electrochemical reduction of molecular oxygen in polar organic …
2011
The voltammetry of microparticles and scanning electrochemical microscopy methodologies are applied to characterize praseodymium centers in praseodymia-doped zircon (PrxZr(1−y)Si(1−z)O4; y + z = x; 0.02 < x < 0.10) specimens prepared via sol–gel synthetic routes. In contact with aqueous electrolytes, two overlapping Pr-centered cathodic processes, attributable to the Pr (IV) to Pr (III) reduction of Pr centers in different sites are obtained. In water-containing, air-saturated acetone and DMSO solutions as solvent, PrxZr(1−y)Si(1−z)O4 materials produce a significant catalytic effect on the electrochemical reduction of peroxide radical anion electrochemically generated. These electrochemical…
Biochar from byproduct to high value added material – A new adsorbent for toxic metal ions removal from aqueous solutions
2018
Abstract An activated biochar coming from pyrolysis of dead Posidonia oceanica residues has been tested as adsorbent material for Cd2+, Pb2+ and Cu2+ ions. The biomass, the activated and the non activated biochars were previously characterized by using several instrumental techniques. The pH of metal ion solution in kinetic and thermodynamic adsorption experiments was fixed at 5 whilst, the dependence on ionic medium, ionic strength and temperature have been evaluated carrying out batch experiments at different experimental conditions. Differential Pulse Anodic Stripping Voltammetry and Inductively Coupled Plasma Optical Emission Spectroscopy have been used to measure the metal ion concentr…
Rhenium(I) and platinum(II) complexes with diimine ligands bearing acidic phenol substituents: hydrogen-bonding, acid-base chemistry and optical prop…
2010
Tricarbonylchloro-rhenium(i) (1-4) and catecholato-platinum(ii) complexes (6, 7) of diimine ligands bearing phenol and O-protected phenol substituents have been prepared and fully characterised including single crystal structure analyses of 1, 4 and 7. The redox behaviour of the catecholato platinum(ii) complexes 6 and 7 has been probed by cyclic voltammetry, preparative oxidation and EPR spectroscopy (6˙(+), 7˙(+)). Reversible deprotonation of the hydroxy substituted complexes 1, 3 and 6 to 1(-), 3(-) and 6(-) resulted in significant changes in their electronic spectra. The luminescence properties of the diamagnetic complexes have been investigated using emission spectroscopy. DFT and TD-D…
Production of highly charged ions of rare species by laser-induced desorption inside an electron beam ion trap
2019
This paper reports on the development and testing of a novel, highly efficient technique for the injection of very rare species into electron beam ion traps (EBITs) for the production of highly charged ions (HCI). It relies on in-trap laser-induced desorption of atoms from a sample brought very close to the electron beam resulting in a very high capture efficiency in the EBIT. We have demonstrated a steady production of HCI of the stable isotope 165Ho from samples of only 1012 atoms (∼300 pg) in charge states up to 45+. HCI of these species can be subsequently extracted for use in other experiments or stored in the trapping volume of the EBIT for spectroscopic measurements. The high efficie…
Calibration of high voltages at the ppm level by the difference of $^{83\mathrm{m}}$Kr conversion electron lines at the KATRIN experiment
2018
The neutrino mass experiment KATRIN requires a stability of 3 ppm for the retarding potential at − 18.6 kV of the main spectrometer. To monitor the stability, two custom-made ultra-precise high-voltage dividers were developed and built in cooperation with the German national metrology institute Physikalisch-Technische Bundesanstalt (PTB). Until now, regular absolute calibration of the voltage dividers required bringing the equipment to the specialised metrology laboratory. Here we present a new method based on measuring the energy difference of two [superscript 83m]Kr conversion electron lines with the KATRIN setup, which was demonstrated during KATRIN’s commissioning measurements in July 2…
Noise-assisted persistence and recovery of memory state in a memristive spiking neuromorphic network
2021
Abstract We investigate the constructive role of an external noise signal, in the form of a low-rate Poisson sequence of pulses supplied to all inputs of a spiking neural network, consisting in maintaining for a long time or even recovering a memory trace (engram) of the image without its direct renewal (or rewriting). In particular, this unique dynamic property is demonstrated in a single-layer spiking neural network consisting of simple integrate-and-fire neurons and memristive synaptic weights. This is carried out by preserving and even fine-tuning the conductance values of memristors in terms of dynamic plasticity, specifically spike-timing-dependent plasticity-type, driven by overlappi…
Synthesis, crystal structures and magnetic properties of mononuclear tris(croconate)ferrate(III) complexes
2006
Abstract A straightforward synthetic method to prepare mononuclear croconato-containing iron (III) complexes, (A)3[Fe(C5O5)3] [A = tetrabutylammonium = n-Bu4N+ (1) and tetraphenylphosphonium = PPh 4 + ( 2 ) ; C 5 O 5 2 - = croconate = dianion of 4 , 5 - dihydroxycyclopent - 4 - ene - 1 , 2 , 3 - trione ] along with their crystal structures and magnetic properties, are reported. The Fe(III) atom adopts a pseudo-octahedral geometry while magnetic susceptibility measurements, in the 2–300 K temperature range, show the occurrence of a high spin state (S = 5/2) in both complexes.