A potential- and charge-consistent model for the adsorption dependence of the semiconductor flatband potential

Licht, Stuart S; Marcu, V.

doi:10.1016/0022-0728(86)80571-x

Cited by 21 publications

(13 citation statements)

References 8 publications

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“…In our previous applications of eqs 9 and 10 to monovalent species adsorption onto CdSe, the maximum slope of the flatband potential which could be realistically generated 28 was substantially less than the 0.12 V/log([CN -] we observe with cyanide addition. Therefore, an adsorption shift of flatband potential does not appear to be consistent with the observed effect of cyanide on cadmium chalcogenide flatband potential.…”

Section: Resultsmentioning

confidence: 73%

“…The extent of flatband variation due to adsorption of monovalent anion, J -, in solution at concentration [J -], will vary with the total number of available adsorption sites on the surface, Γ sat , and θ, the relative portion of these sites that are filled (0 e θ e 1). Given an ion-surface adsorption interaction parameter, f, and a capacity per unit area of the Helmholtz double layer, C H , then at temperature, T, the flatband potential variation with the log of solution concentration is given by 28 where F and R are the Faraday and gas constants. From eq 9, the maximum slope, -dV fb /d ln[J -], is given at 50% of the maximum surface coverage (at θ ) 0.5):…”

Section: Resultsmentioning

confidence: 99%

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Flat Band Variation of n-Cadmium Chalcogenides in Aqueous Cyanide

Licht

Peramunage

1996

J. Phys. Chem.

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Flatband potential, V fb , measurements of n-CdSe in alkaline ferrocyanide electrolytes substantiate trends observed for photoelectrochemical open circuit voltage, V oc , with dissolved cyanide. Similar trends comprising a negative shift of V fb and an increase in V oc with increasing concentration of cyanide are also observed for an n-CdTe alkaline ferrocyanide photoelectrochemical cell, PEC. Modification of an alkaline ferro/ferricyanide electrolyte with KCN, in an n-CdSe or n-CdTe PEC, stabilizes the photocurrent, and increases the V oc by several hundred millivolts. In the approach to the high cyanide concentration limit, V fb for both n-CdSe and n-CdTe in alkaline ferrocyanide approaches a single limiting value of -1.2 V vs ferro/ferricyanide.

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Section: Resultsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Flat Band Variation of n-Cadmium Chalcogenides in Aqueous Cyanide

Licht

Peramunage

1996

J. Phys. Chem.

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“…It is generally assumed that in the case of monovalent species a Nernstian slope for the potential drop in the Helmholtz layer, Df H , at flat band is ln(10)RT/F (59 mV pH À1 at 298.15 K). 44 However, the slope of 59 mV pH À1 and the linearity of the trend in Df H(FB) are not always exhibited; some experimental data and models show slopes in U F(FB) of 61 mV pH À1 , 16 65 mV pH À1 45 and 73 mV pH À1 , 16 while a theoretical study shows non-linear trends in U F(FB) with bulk pH 44 which are caused by non-linear trends in Df H(FB) . Non-linear trends are understood to be a consequence of surface coverage dependent lateral interactions between adsorbed species; in these situations, slopes in Df H as low as 19-38 mV pH À1 41 and 29 mV pH À1 44 have been reported for monovalent species, although the experimental method suggests that the semiconductor was not at the flat band potential during the measurements and hence these slopes are not necessarily relevant to the present discussion.…”

Section: Potential Drop Across the Helmholtz Layermentioning

confidence: 99%

Constraints to the flat band potential of hematite photo-electrodes

Hankin

Alexander

2014

Phys. Chem. Chem. Phys.

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We revisit the fundamental constraints that apply to flat band potential values at semiconductor photo-electrodes. On the physical scale, the Fermi level energy of a non-degenerate semiconductor at the flat band condition, EF(FB), is constrained to a position between the conduction band, EC, and the valence band, EV,: |EC| < |EF(FB)| < |EV| throughout the depth of the semiconductor. The same constraint applies on the electrode potential scale, where the values are referenced against a common reference electrode: UC(FB) < UF(FB) < UV(FB). Some experimentally determined flat band potentials appear to lie outside these fundamental boundaries. In order to assess the validity of any determined flat band potential, the boundaries set by the conduction band and the valence band must be computed on both scales a priori, where possible. This is accomplished with the aid of an analytical reconstruction of the semiconductor|electrolyte interface in question. To illustrate this approach, we provide a case study based on synthetic hematite, α-Fe2O3. The analysis of this particular semiconductor is motivated by the large variance in the flat band potential values reported in the literature.

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“…Yet another tactic involves perturbing the electrostatics at the semiconductor-electrolyte interface by adsorbing (or even chemically attaching) electron donors or acceptors on the semiconductor surface [237]. In favorable cases, this increases the band bending at the interface by thus introducing a fixed countercharge of opposite polarity (negative for a n-type semiconductor) at the junction.…”

Section: 8mentioning

confidence: 99%

Fundamentals of Semiconductor Electrochemistry and Photoelectrochemistry

Rajeshwar

2002

Encyclopedia of Electrochemistry

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The sections in this article are Introduction and Scope Electron Energy Levels in Semiconductors and Energy Band Model The Semiconductor–Electrolyte Interface at Equilibrium The Equilibration Process The Depletion Layer Mapping of the Semiconductor Band‐edge Positions Relative to Solution Redox Levels Surface States and Other Complications Charge Transfer Processes in the Dark Current‐potential Behavior Dark Processes Mediated by Surface States or by Space Charge Layer Recombination Rate‐limiting Steps in Charge Transfer Processes in the Dark Light Absorption by the Semiconductor Electrode and Carrier Collection Light Absorption and Carrier Generation Carrier Collection Photocurrent‐potential Behavior Dynamics of Photoinduced Charge Transfer Hot Carrier Transfer Multielectron Photoprocesses Nanocrystalline Semiconductor Films and Size Quantization Introductory Remarks The Nanocrystalline Film–Electrolyte Interface and Charge Storage Behavior in the Dark Photoexcitation and Carrier Collection: Steady State Behavior Photoexcitation and Carrier Collection: Dynamic Behavior Size Quantization Chemically Modified Semiconductor–Electrolyte Interfaces Single Crystals Nanocrystalline Semiconductor Films and Composites Types of Photoelectrochemical Devices Conclusion Acknowledgments

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A potential- and charge-consistent model for the adsorption dependence of the semiconductor flatband potential

Cited by 21 publications

References 8 publications

Flat Band Variation of n-Cadmium Chalcogenides in Aqueous Cyanide

Flat Band Variation of n-Cadmium Chalcogenides in Aqueous Cyanide

Constraints to the flat band potential of hematite photo-electrodes

Fundamentals of Semiconductor Electrochemistry and Photoelectrochemistry

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