The contribution of surface states to the charge transport process across CdS, CdSe-electrolyte interface

Tyagai, V. A.; Kolbasov, G. Ya.

doi:10.1016/0039-6028(71)90053-7

Cited by 45 publications

(26 citation statements)

References 6 publications

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“…These reactions are decomposition reactions in both acidic and alkaline media. In both cases, tin diffuses out into the solution and a mixture of sulfur and selenium stays on the surface according to the reactions SnSSe + 4h § ~ Sn 4~ + S + Se [6] SnSSe + 4h* + 3H20 --> SnO3= + S + Se + 6H ~ [7] As previously mentioned, corrosion products are identical to those found during the electrode decomposition in the dark in the presence of redox reagents. Substantial improvement can be achieved in the stability in acidic solution containing potassium iodide.…”

Section: Discussionmentioning

confidence: 84%

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Fotouhi

Katty

Gorochov

1985

J. Electrochem. Soc.

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Single crystals of n-type SnS~Se2_x (x = 1.04) obtained both by transport and Bridgman methods exhibit an energy gap of 1.53 eV. The flatband potential is pH dependent, and its values in acidic and alkaline solutions are, respectively, 0.06 and -0.6V (SCE). In the dark, SnSSe is stable in acidic medium, but the stability decreases as pH increases. It is also unstable in acidic solutions containing the oxidizing form of a redox reagent with a sufficiently positive redox potential (ca. more positive than 0.8V/SCE). The presence of an oxidizing form of a redox couple in alkaline medium enhances the already existing corrosion reaction. The corrosion reaction is accompanied with an anodic current. The corrosion rate as well as the magnitude of the anodic current depends on pH and the concentration of the oxidizing state of the couple. Light-driven reactions in both acidic and alkaline media are corrosion reactions. However, decomposition may be avoided in acidic solution containing potassium iodide.The solid solution SnSxSe2_x can be prepared over the entire composition range from SnS2 to SnSe2. Compounds obtained are layered semiconductor with CdI.,-type structure. Optical properties of the mixed series SnSxSe2 x (where 0 < x < 2) have already been studied (1). Indirect energy gaps obtained vary linearly between SnSe2 (1.09 eV) and SnS,.sSe0.5 (1.75 eV). A deviation from linearity is observed between SnS1.sSe0.5 and SnS~ (2.22 eV). Photoelectrochemical properties of SnS2 have already been studied (2), and it seems interesting to consider the ternary compound.Although this ternary compound could present a particular interest in solar energy conversion because of its adjustable energy gap, it has not yet received attention in photoelectrochemistry. SnSSe, whose reported energy gap is 1.52 eV (1), which is an optimum value for solar spectrum, could be an interesting candidate for solar energy conversion into electrical or chemical energy. ExperimentalSnSxSe2_x single crystals were obtained both by transport and Bridgman methods. In both cases, stoichiometric amounts of purified tin sulfur and selenium were used. In the transport method, iodine and bromine were the transporting agents. The charge zone was at 630~ and the transport zone at 580~ Single crystals of SnS~Se2 x (3 • 3 • 0.1 ram) were obtained within a week. In the Bridgman method, the transport zone was fixed at 780~ and the temperature gradient was 70~ Ingots of 10 cm length with 1 cm diam were obtained. Microprobe analysis indicated that the composition of the samples prepared by tranport was x = 1.04. For those prepared by Bridgman technique, the same composition was found for the higher part of the tube (x = 1.05). The composition for the lower and the central parts of the tube was approximately x = 1.2. Hall measurements gave a carrier concentration of 6 • 10 '7 cm -~3 and a resistivity of 0.36 ~-cm at room temperature for samples prepared by transport method, and a carrier concentration of 2 • 10 '" cm -:~ and a resistivity of 200 ~-cm for those prepared...

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Section: Discussionmentioning

confidence: 84%

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Fotouhi

Katty

Gorochov

1985

J. Electrochem. Soc.

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“…For values of q for which w7 9 1, the quantity to be integrated becomes proportional to exp[q(al/kT)], which is a decreasing function of q if a k T c 1. Accepting this inequality, which together with inequality (19) is expressed as 0 c a k T c 1 , (20) f(q).dq can be replaced in the integral associated with E" by Equation (18) for all values of q, since the contribution to the integral at high values of q is negligible. Hence,…”

Section: Interpretation Of the Frequency-dependencementioning

confidence: 99%

“…Data on the frequency-dependence of R, in the case of the lithiated NiO electrode, contained in papers by Rouse and Weininger [9] and by Tench and Yeager [lo], indicate that Equation (1) is also roughly valid for this semiconductor electrode material. In a couple of cases of semiconductor electrodes under the circumstances specified above, namely Ge [18], CdS [19] and CdSe [20], a relationship for the a.c. conductance G = RP ', of the form R i ' -w (12) and valid within a limited frequency range, has been mentioned without interpretation. Since in our results the dissipation D is small, so that Equation (11) holds, it can be seen that our experimental relationship (1) is equivalent to Equation (12), provided that the contribution of b to R, is either sufficiently small or taken into account.…”

Section: Introductory Remarksmentioning

confidence: 99%

“…[19], as well as the CdSe samples of refer. [20], which appeared to obey to relationship (12), were as-grown thin platelets exhibiting natural and hence very smooth surfaces; it is finally interesting to note that in the case of Pt covered with a thin oxide film, in which relations (1) and (2) were found to be valid, surface roughness appeared not to influence the magnitude of the frequency-dispersion [28].…”

Section: Introductory Remarksmentioning

confidence: 99%

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Investigation on the frequency‐dependence of the impedance of the nearly ideally polarizable semiconductor electrodes CdSe, CdS and TiO₂

Dutoit¹,

Meirhaeghe²,

Cardon³

et al. 1975

Ber Bunsenges Phys Chem

172

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The impedance of several nearly ideally polarizable semiconductor electrodes (CdSe, CdS, TiO,) has been studied as a function of applied voltage and of frequency. The differential capacitance and resistance appear to obey to simple frequency laws. A mathematical model accounting for these laws is presented, in which a distribution of time constants is assumed, associated with dielectric relaxation phenomena in the double layer at the semiconductor/electrolyte interface. The experimental results indicate, that the source of the frequency-dependence has to be sought in structural irregularities of the surface region of the electrode. The proposed model appears to be also applicable to results, mentioned in the literature, concerning other semiconductor/electrolyte systems. The possibility of determining the flat-band potential from frequency-dependent capacitance data is discussed. Die Impedanz verschiedener fast ideal polarisierbaren Halbleiterelektroden (CdSe, CdS, TiO,) wurde in Abhangigkeit yon der angelegten Spannung und der Frequenz untersucht. Die Differentialkapazitat und der Differentialwiderstand zeigen einfache Frequenzabhangigkeiten. Diese Gesetze werden aufgrund eines mathematischen Modells gedeutet, in dem eine Verteilung von Zeitkonstanten angenommen wird, die mit dielektrischen Relaxationserscheinungen in der Doppelschicht an der Halbleiter/Elektrolyt-Phasengrenze in Zusammenhang stehen. Die Ergebnisse deuten darauf hin, Strukturdefekte im Oberflachengebiet der Elektrode seien fur die Frequenzabhangigkeit verantwortlich. Es zeigt sich, daO das vorgeschlagene Modell auch auf Literaturergebnisse betrefis anderer Halbleiter/Elektrolyt-Systeme anwendbar ist. Die Moglichkeit, das Flachbandpotential aus frequenzabhangigen Kapazitatsergebnissen zu bestimmen, wird besprochen.

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“…In order to obtain better spectral matching to the solar spectrum, faster charge transfer to the solution and a higher band bending, {Fe(CN)~} 4 ':~-has been used as an alternative redox couple. With CdSe only partial stability was reported, as evidenced by the formation of surface precipitates (22)(23)(24) or by a reduction of current multiplication due to organic redox systems (25). With CdSe only partial stability was reported, as evidenced by the formation of surface precipitates (22)(23)(24) or by a reduction of current multiplication due to organic redox systems (25).…”

mentioning

confidence: 99%

Stability of CdSe and Se Layers in K 4 [ Fe ( CN ) 6 ] / K 3 [ Fe ( CN ) 6 ] Solutions

Marcu

Strehblow

1991

J. Electrochem. Soc.

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The photoelectrochemistry of CdSe and CdSe/Se has been examined by cyclic voltammetry in a 0.1M KC1 solution in the presence of various concentrations of K3[Fe(CN)sl and K4[Fe(CN)G]. The above mentioned redox species stabilize both Se and CdSe with regard to photo-oxidation and reduction. A stabilization efficiency, S, defined as the ratio of charge transfer current to the redox species vs. total current, is measured. For CdSc a value S = 0.6 is reported, while for Se reduction S = 0.3 (crcd = 10 2M). The potential at which the photocurrent appears (onset potential) changes with the direction of the voltage scan and the nature of the redox species present in the solution. These results may be useful for applications of CdSe/Se junctions for solar energy conversion.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-25 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-25 to IP

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The contribution of surface states to the charge transport process across CdS, CdSe-electrolyte interface

Cited by 45 publications

References 6 publications

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Investigation on the frequency‐dependence of the impedance of the nearly ideally polarizable semiconductor electrodes CdSe, CdS and TiO₂

Stability of CdSe and Se Layers in K 4 [ Fe ( CN ) 6 ] / K 3 [ Fe ( CN ) 6 ] Solutions

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The contribution of surface states to the charge transport process across CdS, CdSe-electrolyte interface

Cited by 45 publications

References 6 publications

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Investigation on the frequency‐dependence of the impedance of the nearly ideally polarizable semiconductor electrodes CdSe, CdS and TiO2

Stability of CdSe and Se Layers in K 4 [ Fe ( CN ) 6 ] / K 3 [ Fe ( CN ) 6 ] Solutions

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Investigation on the frequency‐dependence of the impedance of the nearly ideally polarizable semiconductor electrodes CdSe, CdS and TiO₂