On the kinetics of charge transfer between an illuminated CdSe electrode and polysulphide electrolyte

Abstract The interface between CdSe and aqueous polysulphide solutions was investigated by impedance measurements. Variations in the flat-band potential as a function of solution parameters such as polysulphide concentration, hydroxide ion, added salt and cation effect were investigated. Furthermore, under illumination shifts in the flat-band potential were observed which were studied as a function of the above parameters. The findings of this investigation were as follows: (1) The flat-band potential was found to vary linearly with the redox potential of the polysulphide solution, which suggests a pinning of the Fermi level. (2) It was observed that the flat-band shifts were smaller in stabilizing solutions, i.e. charge accumulation at the interface led to appreciable shifts in the flat-band potential and to photocorrosion of the semiconductor. (3) Added hydroxide led to smaller flat-band shifts and to a larger stability of the photoelectrode. (4) Barium ion was found to have similar effects to that of caesium ion. (5) Adding salt to the polysulphide solution led to a decrease in the flat-band shifts of the photoelectrode. The results of this study are discussed in the light of recent models for the charge-transfer kinetics at this interface.

[1]  S. Licht,et al.  The Effect of Hydroxide Ion on Cd‐Chalcogenide/Aqueous Polysulfide Photoelectrochemical Cells , 1985 .

[2]  R. Tenne,et al.  High efficiency n‐Cd(Se,Te)/S=photoelectrochemical cell resulting from solution chemistry control , 1985 .

[3]  R. Tenne,et al.  A Pronounced Cation Effect on Performance and Stability of Cd‐Chalcogenide/Polysulfide Photoelectrochemical Cells , 1984 .

[4]  R. Tenne,et al.  Cation Effects on the Electrochemistry of Anions in Polysulfide Photoelectrochemical Cells , 1986 .

[5]  K. W. Frese.  Capacitance/voltage studies on etched and anodized single‐crystal n‐CdSe , 1982 .

[6]  J. Winnick,et al.  Polysulfide Solution Chemistry at a CdSe Photoanode , 1988 .

[7]  P. Allongue,et al.  Charge transfer and stabilization at illuminated n-GaAs/aqueous electrolyte junctions , 1988 .

[8]  P. Claes,et al.  Electrochemical-behavior of Nitrate and Nitrite Ions in the Molten Naoh-koh (49 M/o) Eutectic Mixture At 250-degrees-c , 1982 .

[9]  W. Giggenbach.  Optical spectra and equilibrium distribution of polysulfide ions in aqueous solution at 20.deg. , 1972 .

[10]  S. Licht,et al.  The High Aqueous Solubility of K 2 S and Its Effect on Bulk and Photoelectrochemical Characteristics of Cd ( SeTe ) / S x = Cells II . Variation of Sulfur/Sulfide Ratio , 1986 .

[11]  J. Yates,et al.  Electron-Stimulated Desorption and Work Function Studies of Clean and Cesiated (110) GaAs , 1971 .

[12]  Reshef Tenne,et al.  A light-variation insensitive high efficiency solar cell , 1987, Nature.

[13]  P. Allongue,et al.  Flatband potential determination and surface modifications at semiconductor-liquid junctions , 1985 .