The photovoltaic properties and structure of palladium tetraphenylporphyrin on tin oxide photoelectrochemical cells

1981 ◽  
Vol 59 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Cooper H. Langford ◽  
Bryan R. Hollebone ◽  
Daniel Nadezhdin
Keyword(s):  
Redox Reactions ◽  
Magnetic Circular Dichroism ◽  
Transparent Electrode ◽  
Axial Ligand ◽  
Film Structure ◽  
Photoelectrochemical Cells ◽  
Qualitative Explanation ◽  
Photovoltaic Properties ◽  
As Doping ◽  
History Of

The photovoltaic properties of palladium tetraphenylporphyrin films on n-doped SnO2 transparent electrode in contact with a solution of quinone/hydroquinone are discussed as a function of the preparation of the film and history of its treatment with heat, H2, or O2/H2O. Magnetic circular dichroism (MCD) spectra of the electrodes provide guidance on film structure. There are three important results. First, MCD spectra show that photovoltaic behaviour is independent of crystallinity of the film. Second, the evolution of film behaviour as "doping" by O2/H2O occurs shows that photoprocesses occur at both the interface of the film with SnO2 and the electrolyte, leading to both photoanodic and photocathodic processes. Third, MCD spectra show that "doping" is not a surface or trace phenomenon but affects the axial ligand sensitive region of the spectra of molecules throughout the film. Transport of charge through the film by successive "redox" reactions appears to provide the simplest qualitative explanation of the results. That is, conduction is by hopping in a non-stoichiometrically oxidized film.

Manganese(III) and manganese(IV) corroles: synthesis, spectroscopic, electrochemical and X-ray structural characterization

2005 ◽  
Vol 09 (06) ◽  
pp. 398-412 ◽  
Author(s):  
Zhongping Ou ◽  
Christoph Erben ◽  
Marie Autret ◽  
Stefan Will ◽  
Daniel Rosen ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Esr Spectroscopy ◽  
Spectroscopic Characterization ◽  
Axial Ligand ◽  
X Ray Diffraction ◽  
Nonaqueous Media ◽  
X Ray ◽  
Cation Radicals ◽  
Uv Visible ◽  
Electron Reduction

The synthesis, spectroscopic characterization and electrochemistry of four Mn(III) and Mn(IV) octaethylcorroles are reported and the potentials of the Mn(III) / Mn(IV) and Mn(IV) / Mn(III) processes examined as a function of the axial ligand. The investigated compounds are represented as ( OEC ) Mn , ( OEC ) MnCl , ( OEC ) Mn ( py ) and ( OEC ) Mn ( C 6 H 5) where OEC is the trianion of octaethylcorrole. The first one-electron oxidation of ( OEC ) Mn III and ( OEC ) Mn III ( py ) in PhCN or pyridine containing 0.1 M TBAP leads to the facile formation of a Mn(IV) species while the first one-electron reduction of ( OEC ) Mn IV Cl and ( OEC ) Mn IV ( C 6 H 5) in the same two solvents leads to the Mn(III) corrole. All other redox reactions occur at the corrole macrocycle to give π-cation radicals or π-anion radicals and there is no evidence for electrogeneration of a compound with a Mn(II) oxidation state as is the case for manganese(III) porphyrins which are all easily reduced to the Mn(II) state in nonaqueous media. The products of each Mn(III)/Mn(IV) redox reaction were characterized by UV-visible and/or ESR spectroscopy and the structures of ( OEC ) MnCl , ( OEC ) Mn ( py ) and ( OEC ) Mn ( C 6 H 5) were determined by single-crystal X-ray diffraction.

Progress and Limits of the Numerical Simulation of SiC Bulk and Epitaxy Growth Processes

2005 ◽  
Vol 483-485 ◽  
pp. 3-8 ◽  
Author(s):  
Michel Pons ◽  
Elisabeth Blanquet ◽  
Jean Marc Dedulle ◽  
M. Ucar ◽  
Peter J. Wellmann ◽  
...  
Keyword(s):  
Process Equipment ◽  
Simulation Experiments ◽  
Training Tool ◽  
As Doping ◽  
Weakest Link ◽  
Combined Use ◽  
New Process ◽  
History Of ◽  
Further Development ◽  
Electrical Data

Modeling and simulation of the SiC growth process is sufficiently mature to be used as a training tool for engineers as well as a decision making tool, e.g. when building new process equipment or up-scaling old ones. It is possible to simulate accurately temperature and deposition distributions, as well as doping. The key of success would be the combined use of simulation, experiments and characterization in a "daily interaction". The main limitation in SiC growth modeling is the accurate knowledge of physical, thermal, radiative, chemical and electrical data for the different components of the reactor. This is the weakest link in developing completely predictive models. In addition, the link between the thermochemical history of the grown material and its structure and defects still needs further development and input of experimental data.

scholarly journals Oxygen Plasma Surface Treatment onto ITO Surface for OLEDs Based on Europium Complex

2015 ◽  
Vol 10 (1) ◽  
pp. 7-12
Author(s):  
Gerson Santos ◽  
Marco R. Cavallari ◽  
Fernando J. Fonseca ◽  
Luiz Pereira
Keyword(s):  
Surface Treatment ◽  
Indium Tin Oxide ◽  
Oxygen Plasma ◽  
Transparent Electrode ◽  
Film Structure ◽  
Hole Injection ◽  
Light Emitting ◽  
Plasma Surface ◽  
Plasma Surface Treatment ◽  
Cie Chromaticity

In this work, Organic Light-Emitting Diodes (OLEDs) based on Europium (III) complex were studied, especially those with an oxygen plasma surface treatment onto indium tin oxide (ITO) transparent electrode. An OLED with the same thin-film structure but with untreated ITO was fabricated for comparison purposes. Current density-voltage characteristics for treated devices demonstrated an increase from 0.4 to 3.3 mA/cm² and a decrease of the turn-on voltage from 28 to 22 V. Additionally, improved hole injection through the transparent electrode impacted on optical response, as luminous efficiency increased from 26 to 44 mcd/A with the advantage of no significant disturb on the europium typical electroluminescence emission spectrum. Emission peak was observed at a wavelength of approximately 614 nm, which is defined by the transition associated with spectroscopic terms (5D0→7D2) and CIE chromaticity coordinates of (0.50;0.36).

Synthesis, electrochemical, photovoltaic, and photo-physical properties on the lanthanide(III) complexes of acetylacetonate and meso-tetraalkyltetrabenzoporphyrin with electric-field induction

2004 ◽  
Vol 08 (10) ◽  
pp. 1187-1195 ◽  
Author(s):  
Ming-Hui Qi ◽  
Guo-Fa Liu
Keyword(s):  
Electric Field ◽  
Redox Reactions ◽  
Soret Band ◽  
Luminescence Spectroscopy ◽  
Quantum Yields ◽  
Surface Photovoltage ◽  
Absorption Bands ◽  
Photovoltaic Properties ◽  
Surface Photovoltage Spectroscopy ◽  
Spectral Bands

Lanthanide(III) complexes with acetylacetonate and meso-tetraalkyltetrabenzoporphyrin (TATBP) having the general formula Ln ( TATBP )acac (where Ln = Tb , Dy , Ho , Er , Tm , Yb ; A = C 12 H 25; Hacac = acetylacetone) are reported. These compexes have been studied by elemental analyses, ultraviolet visible spectra, infrared spectra, molar conductance, 1 H NMR spectra, cyclic voltammetry, surface photovoltage spectroscopy (SPS), and luminescence spectroscopy. The infrared spectral bands of the ligand and complexes were assigned. In dimethylformamide (DMF), 0.1 M tetrabutylammonium perchlorate (TBAP), the synthesized TATBP exhibit two one-electron reversible redox reactions, and Ln(TATBP)acac shows three redox reactions respectively, within the accessible potential window of the solvent. The absorption bands of the complexes appear in the range 431-433 (Soret band), 578-580 (Q band) and 627-631 (Q band) nm. The photovoltaic properties and charge transfer process of these compounds were investigated by surface photovoltage spectroscopy (SPS) and electric-field-induced surface photovoltage spectroscopy (EFISPS) techniques, which reveal that the ligand TATBP and the complexes Er(TATBP)acac are p-type semiconductors. The spectral bands of TATBP correspond to π → π* transitions. Quantum yields of the S 1 → S 0 fluorescence are in the region 0.25-0.27 and the fluorescence lifetimes are in the region 0.014-0.022 ms at room temperature. The phosphorescence bands of the complex at 77 K appears 714 nm.

scholarly journals In Operando Deconvolution of Photovoltaic and Electrocatalytic Performance in ALD TiO2 Protected Water Splitting Photocathodes

2017 ◽  
Author(s):  
David Tilley ◽  
Wei Cui ◽  
Wenzhe Niu ◽  
René Wick ◽  
Thomas Moehl
Keyword(s):  
Charge Transfer ◽  
Water Splitting ◽  
Degradation Mechanism ◽  
Model System ◽  
Photoelectrochemical Cells ◽  
Material System ◽  
Surface Kinetics ◽  
Photovoltaic Properties ◽  
Electrocatalytic Performance ◽  
In Operando

<p>Many present-day investigations of water splitting photoelectrodes are based on buried p–n junctions, which usually offer an improved photovoltage and therefore a higher solar-to-hydrogen efficiency in tandem photoelectrochemical cells. In this work, we demonstrate that the dual working electrode (DWE) technique enables the measurement of the surface potential of water splitting buried-junction photocathodes under operation, enabling the deconvolution of the photovoltaic and electrocatalytic performance <i>in operando</i>. Consequently, we can access properties of the buried p–n junction independent of the surface kinetics, and gain information related to the charge transfer through the electrode/electrolyte interface independent of the photovoltaic properties. Moreover, the DWE technique provides a clearer understanding of the photocathode degradation mechanism during stability tests. Two p–n junction-based photocathodes are investigated in this work: a pn<sup>+</sup>-Si/TiO<sub>2</sub> photocathode as model system, and the application of the developed method to the emerging material system Cu<sub>2</sub>O/Ga<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub>. </p>

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