Browse
Submit Data
Databases
API
Help

Dataset Information

16 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Layer-resolved ultrafast extreme ultraviolet measurement of hole transport in a Ni-TiO2-Si photoanode.

ABSTRACT: Metal oxide semiconductor junctions are central to most electronic and optoelectronic devices, but ultrafast measurements of carrier transport have been limited to device-average measurements. Here, charge transport and recombination kinetics in each layer of a Ni-TiO2-Si junction is measured using the element specificity of broadband extreme ultraviolet (XUV) ultrafast pulses. After silicon photoexcitation, holes are inferred to transport from Si to Ni ballistically in ~100 fs, resulting in characteristic spectral shifts in the XUV edges. Meanwhile, the electrons remain on Si. After picoseconds, the transient hole population on Ni is observed to back-diffuse through the TiO2, shifting the Ti spectrum to a higher oxidation state, followed by electron-hole recombination at the Si-TiO2 interface and in the Si bulk. Electrical properties, such as the hole diffusion constant in TiO2 and the initial hole mobility in Si, are fit from these transient spectra and match well with values reported previously.

SUBMITTER: Cushing SK

PROVIDER: S-EPMC7124930 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Real-time and sub-wavelength ultrafast coherent diffraction imaging in the extreme ultraviolet.

Project description:Coherent Diffraction Imaging is a technique to study matter with nanometer-scale spatial resolution based on coherent illumination of the sample with hard X-ray, soft X-ray or extreme ultraviolet light delivered from synchrotrons or more recently X-ray Free-Electron Lasers. This robust technique simultaneously allows quantitative amplitude and phase contrast imaging. Laser-driven high harmonic generation XUV-sources allow table-top realizations. However, the low conversion efficiency of lab-based sources imposes either a large scale laser system or long exposure times, preventing many applications. Here we present a lensless imaging experiment combining a high numerical aperture (NA = 0.8) setup with a high average power fibre laser driven high harmonic source. The high flux and narrow-band harmonic line at 33.2 nm enables either sub-wavelength spatial resolution close to the Abbe limit (Δr = 0.8λ) for long exposure time, or sub-70 nm imaging in less than one second. The unprecedented high spatial resolution, compactness of the setup together with the real-time capability paves the way for a plethora of applications in fundamental and life sciences.

| S-EPMC4258652 | biostudies-literature

Conical-intersection dynamics and ground-state chemistry probed by extreme-ultraviolet time-resolved photoelectron spectroscopy.

Project description:Time-resolved photoelectron spectroscopy (TRPES) is a useful approach to elucidate the coupled electronic-nuclear quantum dynamics underlying chemical processes, but has remained limited by the use of low photon energies. Here, we demonstrate the general advantages of XUV-TRPES through an application to NO2, one of the simplest species displaying the complexity of a non-adiabatic photochemical process. The high photon energy enables ionization from the entire geometrical configuration space, giving access to the true dynamics of the system. Specifically, the technique reveals dynamics through a conical intersection, large-amplitude motion and photodissociation in the electronic ground state. XUV-TRPES simultaneously projects the excited-state wave packet onto many final states, offering a multi-dimensional view of the coupled electronic and nuclear dynamics. Our interpretations are supported by ab initio wavepacket calculations on new global potential-energy surfaces. The presented results contribute to establish XUV-TRPES as a powerful technique providing a complete picture of ultrafast chemical dynamics from photoexcitation to the final products.

| S-EPMC6082858 | biostudies-other

Ultrafast carrier thermalization and trapping in silicon-germanium alloy probed by extreme ultraviolet transient absorption spectroscopy.

Project description:Semiconductor alloys containing silicon and germanium are of growing importance for compact and highly efficient photonic devices due to their favorable properties for direct integration into silicon platforms and wide tunability of optical parameters. Here, we report the simultaneous direct and energy-resolved probing of ultrafast electron and hole dynamics in a silicon-germanium alloy with the stoichiometry Si0.25Ge0.75 by extreme ultraviolet transient absorption spectroscopy. Probing the photoinduced dynamics of charge carriers at the germanium M4,5-edge (∼30 eV) allows the germanium atoms to be used as reporter atoms for carrier dynamics in the alloy. The photoexcitation of electrons across the direct and indirect band gap into conduction band (CB) valleys and their subsequent hot carrier relaxation are observed and compared to pure germanium, where the Ge direct [Formula: see text] and Si0.25Ge0.75 indirect gaps ([Formula: see text]) are comparable in energy. In the alloy, comparable carrier lifetimes are observed for the X, L, and Γ valleys in the conduction band. A midgap feature associated with electrons accumulating in trap states near the CB edge following intraband thermalization is observed in the Si0.25Ge0.75 alloy. The successful implementation of the reporter atom concept for capturing the dynamics of the electronic bands by site-specific probing in solids opens a route to study carrier dynamics in more complex materials with femtosecond and sub-femtosecond temporal resolution.

| S-EPMC5461173 | biostudies-other

Investigating ultrafast carrier dynamics in perovskite solar cells with an extended π-conjugated polymeric diketopyrrolopyrrole layer for hole transportation.

Project description:Here, we show a new diketopyrrole based polymeric hole-transport material (PBDTP-DTDPP, (poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[[2,2'-(4,8-bis(4-ethylhexyl-1-phenyl)-benzo[1,2-b:4,5-b']dithiophene)bis-thieno[3,2-b]thiophen]-5,5'-diyl]])) for application in perovskite solar cells. The material performance was tested in a solar cell with an optimized configuration, FTO/SnO2/perovskite/PBDTP-DTDPP/Au, and the device showed a power conversion efficiency of 14.78%. The device charge carrier dynamics were investigated using transient absorption spectroscopy. The charge separation and recombination kinetics were determined in a device with PBDTP-DTDPP and the obtained results were compared to a reference device. We find that PBDTP-DTDPP enables similar charge separation time (<∼4.8 ps) to the spiro-OMeTAD but the amount of nongeminate recombination is different. Specifically, we find that the polymeric PBDTP-DTDPP hole-transport layer (HTL) slows-down the second-order recombination much less than spiro-OMeTAD. This effect is of particular importance in studying the charge transportation in optimized solar cell devices with diketopyrrole based HTL materials.

| S-EPMC9049750 | biostudies-literature

Effect of Ni/Si Mass Ratio and Thermomechanical Treatment on the Microstructure and Properties of Cu-Ni-Si Alloys.

Project description:The effect of the Ni/Si mass ratio and combined thermomechanical treatment on the microstructure and properties of ternary Cu-Ni-Si alloys is discussed systematically. The Cu-Ni-Si alloy with a Ni/Si mass ratio of 4-5 showed good comprehensive properties. Precipitates with disc-like shapes were confirmed as the Ni2Si phase with orthorhombic structure through transmission electron microscopy, high-resolution transmission electron microscopy, and 3D atom probe characterization. After the appropriate thermomechanical treatment, the studied alloy with a Ni/Si mass ratio of 4.2 exhibited excellent mechanical properties: a hardness of 290 HV, tensile strength of 855 MPa, yield strength of 782 MPa, and elongation of 4.5%. Compared with other approaches, the thermomechanical treatment increased the hardness and strength without sacrificing electrical conductivity. Theoretical calculations indicated that the high strength was primarily attributed to the Orowan precipitation strengthening and secondarily ascribed to the work hardening, which were highly consistent with the experimental results. The appropriate Ni/Si mass ratio with a low content of Ni and Si atoms shows high strength and excellent electrical conductivity through combined thermomechanical treatment. This work provides a guideline for the design and preparation of multicomponent Cu-Ni-Si-X alloys with ultrahigh strength and excellent electrical conductivity.

| S-EPMC6650849 | biostudies-literature

Photoelectrocatalytic degradation of high-density polyethylene microplastics on TiO2-modified boron-doped diamond photoanode

Project description: Not available

| S-EPMC10906510 | biostudies-literature

Time-resolving the ultrafast H2 roaming chemistry and H3+ formation using extreme-ultraviolet pulses.

Project description:The time scales and formation mechanisms of tri-hydrogen cation products in organic molecule ionization processes are poorly understood, despite their cardinal role in the chemistry of the interstellar medium and in other chemical systems. Using an ultrafast extreme-ultraviolet pump and time-resolved near-IR probe, combined with high-level ab initio molecular dynamics calculations, here we report unambiguously that H3+ formation in double-ionization of methanol occurs on a sub 100 fs time scale, settling previous conflicting findings of strong-field Coulomb explosion experiments. Our combined experimental-computational studies suggest that ultrafast competition, between proton-transfer and long-range electron-transfer processes, determines whether the roaming neutral H2 dynamics on the dication result in [Formula: see text] or [Formula: see text] fragments respectively.

| S-EPMC9814522 | biostudies-literature

Extreme-ultraviolet high-harmonic generation in liquids.

Project description:High-harmonic generation (HHG) in gases has been the main enabling technology of attosecond science since its discovery. Recently, HHG from solids has been demonstrated, opening a lively area of research. In contrast, harmonic generation from liquids has so far remained restricted to low harmonics in the visible regime. Here, we report the observation and detailed characterization of extreme ultraviolet HHG from liquid water and several alcohols extending beyond 20?eV. This advance was enabled by the implementation of the recent liquid flat-microjet technology, which we show to facilitate the spatial separation of HHG from the bulk liquid and the surrounding gas phase. We observe striking differences between the HHG spectra of water and several alcohols. A comparison with a strongly-driven few-band model establishes the sensitivity of HHG to the electronic structure of liquids. Our results suggest liquid-phase high-harmonic spectroscopy as a new method for studying the electronic structure and ultrafast scattering processes in liquids.

| S-EPMC6137105 | biostudies-literature

Ni(2)Si(P(2)O(7))(2).

Project description:Dinickel(II) silicon bis-[diphosphate(4-)], Ni(2)Si(P(2)O(7))(2), is isotypic with other phosphates of the formula M(2)Si(P(2)O(7))(2) (M = Co, Cd). All atoms except Si (site symmetry 2) are found in general positions. Ni(2)O(10) dimers formed from edge-sharing NiO(6) octa-hedra are linked by corners and O-P-O bridges, forming slabs parallel to (100), which are in turn inter-connected by O-Si-O contacts.

| S-EPMC2969362 | biostudies-literature

First-Principles Band Alignments at the Si:Anatase TiO2 Interface

Project description:TiO2 has been identified as a promising electron

| S-EPMC10249118 | biostudies-literature