Search results for "Photocurrent"
showing 10 items of 140 documents
Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy
2009
Two different electrochemical techniques, differential admittance and photocurrent spectroscopy, for the characterization of electronic and solid state properties of passive films and corrosion layers are described and critically evaluated. In order to get information on the electronic properties of passive film and corrosion layers as well as the necessary information to locate the characteristic energy levels of the passive film/electrolyte junction like: flat band potential (Ufb), conduction band edge (EC) or valence band edge (EV), a wide use of Mott-Schottky plots is usually reported in corrosion science and passivity studies. It has been shown, in several papers, that the use of simpl…
High-sensitive switchable photodetector based on BiFeO3 film with in-plane polarization
2015
A high-sensitive and fast-response photodetector based on BiFeO3 (BFO) ferroelectric thin film is fabricated using coplanar electrode configuration. A large photocurrent/dark current ratio is found up to two orders of magnitude at 1 V bias. Enhanced photocurrent and rectification behavior of the photodetector are observed after applying high voltage pulses to the BFO film. The short-circuit current varies systematically with the poling process and increases linearly with the light density. On the contrary, the open-circuit voltage keeps as a constant during the measurements. We attribute these behaviors to the depolarization field and the interfacial fields at the film-electrode interfaces.…
Impact of π-conjugation configurations on the photovoltaic performance of the quinoxaline-based organic dyes
2017
Abstract Three novel quinoxaline-based donor-π-acceptor type organic dyes were synthesized and explored as sensitizers in dye-sensitized solar cells (DSSCs). The impacts of various π-conjugation configurations which contain different quinoxaline derivatives on the absorption properties, electrochemical properties and photovoltaic performances, as well as theoretical calculations have been investigated systematically. The photovoltaic performances of these dyes were found to be highly relevant to the π-conjugated configurations. In particular, the DSSC based on the dye with 2,3-dioctylquinoxaline as the spacer exhibited the highest efficiency of 8.20% with a short-circuit photocurrent densit…
Comparison of the electrochemical properties of hematite thin films prepared by spray pyrolysis and electrodeposition
2015
Abstract This manuscript reports differences between the photoelectrochemical (PEC) activity of hematite (α-Fe 2 O 3 ) photoanodes produced by cathodic electrodeposition (ED) and spray pyrolysis (SP) methods. Both methods yield nanostructured polycrystalline α-Fe 2 O 3 thin films without additional impurity phases. However, α-Fe 2 O 3 produced by ED is characterised to have better crystallinity and higher porosity, which was confirmed by XRD and SEM analysis. Owing to this, α-Fe 2 O 3 obtained by ED generates a photocurrent that is 2.5 times higher than α-Fe 2 O 3 thin films prepared by SP. Furthermore, the influence of the thickness of the α-Fe 2 O 3 thin films on the flat-band potential p…
Plasmon-enhanced photocurrent in quasi-solid-state dye-sensitized solar cells by the inclusion of gold/silica core–shell nanoparticles in a TiO2 phot…
2013
Direct evidence of the effects of the localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs) in TiO2 photoanodes on the performance enhancement in quasi-solid-state dye-sensitized solar cells (DSCs) is reported by comparing gold/silica core–shell nanoparticles (Au@SiO2 NPs) and hollow silica nanoparticles with the same shell size of the core–shell nanoparticles. The Au nanoparticles were shelled by a thin SiO2 layer to produce the core–shell structure, and the SiO2 hollow spheres were made by dissolving the Au cores of the gold/silica core–shell nanoparticles. Therefore, the size and morphology of the SiO2 hollow spheres were the same as the Au@SiO2 NPs. The energy conver…
Physicochemical characterisation of thermally aged anodic films on magnetron sputtered niobium
2010
The influence of thermal aging, at intermediate temperature (1h at 250°C) and in different environments, on the electronic and solid-state properties of stabilized 160 nm thick amorphous anodic niobia, grown on magnetron sputtered niobium metal, has been studied. A detailed physicochemical characterisation of the a-Nb2O5/0.5M H2SO4 electrolyte junction has been carried out by means of photocurrent and electrochemical impedance spectroscopy as well by differential admittance measurements. A change in the optical band gap (3.45 eV) of niobia film has been observed after aging (3.30 eV) at 250°C in air for 1 hour. A cathodic shift (0.15-0.2 Volt) in the flat band potential of the junction has …
Amorphous semiconductor-electrolyte junctions. Photoelectrochemical behaviour of thin Nb2O5anodic films
1987
An approach to the study of the photocharacteristics of amorphous semiconductor/electrolyte junctions is proposed which takes into account the main differences in the electronic structure and the transport properties of the amorphous semiconductors (a-SC) with respect to the crystalline counterparts. The influence of the wavelength of the incident light on the photocurrent vs electrode potential curves is explained on the basis of the geminate recombination theory in a-SC. The implications of the model are shortly discussed.
Photoelectrochemical characterization of photocatalysts
2021
Abstract This chapter aims to provide an overview of the photoelectrochemical characterization of semiconducting photocatalysts and, in particular, present Photocurrent Spectroscopy (PCS) as a useful tool in determining the band structure of semiconducting/insulating materials. Some fundamentals on PCS will be provided looking at the experimental setup and underlying its advantages and disadvantages. Then, the photoelectrochemical behavior of a semiconductor/electrolyte junction under irradiation will be presented, also taking into account its crystalline or amorphous nature, highlighting how it is possible to get information on the energetics of the junction. This will be exploited to show…
Direct measurement of optical losses in plasmon-enhanced thin silicon films (Conference Presentation)
2018
Plasmon-enhanced absorption, often considered as a promising solution for efficient light trapping in thin film silicon solar cells, suffers from pronounced optical losses i.e. parasitic absorption, which do not contribute to the obtainable photocurrent. Direct measurements of such losses are therefore essential to optimize the design of plasmonic nanostructures and supporting layers. Importantly, contributions of useful and parasitic absorption cannot be measured separately with commonly used optical spectrophotometry. In this study we apply a novel strategy consisting in a combination of photocurrent and photothermal spectroscopic techniques to experimentally quantify the trade-off betwee…
On the Semiconductor Spectroscopy for Identification of Emergent Contaminants in Transparent Mediums
2021
In this chapter, we present a theoretical study of photoelectronic processes in experimental silicon \({n}^{+}{\text{-}}p{\text{-}}{n}^{+}\) structures with applications in identifying emergent contaminants in aqueous medium. Contribution due to various mechanisms of photon absorption to the total photocurrent is calculated. Various mechanisms, such as the influence of tunneling on the spectral characteristic and selective spectral photosensitivity of samples under investigation were investigated. The nature of the relationship between energy parameters of the absorbed waves and the structural parameters is revealed. Expressions are obtained for photocurrent with and without external diffus…