n-CuInSe/sub 2/ based photoelectrochemical cells: Improved, stable performance in aqueous polyiodide through rational surface and solution modifications
Surface optimization of n-CuInSe/sub 2/ crystals by chemical etching in Br/sub 2//MeOH and subsequent thermal oxidation results in >10% efficient photanodes in neutral aqueous polyiodide. The etchant removes a near-stoichiometric surface layer and thermal oxidation leads to In--O bond formation. We find from (photo) electrochemical studies in acetonitrile and in the iodide electrolyte that, upon semiconductor decomposition, Cu ions are released into the solution, consistent with solid state chemical studies that show the existence of the chalcopyrite phase also towards Cu-poor compositions. Addition of Cu ions, as also reported by S. Menezes, H. J. Lewerenz, and K. J. Bachmann (Nature (London) 305, 615 (1983)) or Cu and In ions to the iodide solution drastically decreases photoanode decomposition. Covering the electrode with an extra film of oxidized indium results in true stabilization, at up to 11.7% conversion efficiency under 120-mW/cm/sup 2/ tungsten-halogen illumination. Because, in the presence of Cu ions and under illumination, iodide solutions are not completely stable towards oxidation by O/sub 2/, especially if the solution is acidic, an air-free electrolyte needs to be used.
- Research Organization:
- Solar Energy Research Institute, Golden, Colorado 80401
- DOE Contract Number:
- AC02-83CH10093
- OSTI ID:
- 6476835
- Journal Information:
- Appl. Phys. Lett.; (United States), Journal Name: Appl. Phys. Lett.; (United States) Vol. 45:7; ISSN APPLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
ANODES
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
COPPER COMPOUNDS
COPPER IONS
COPPER SELENIDES
DISPERSIONS
EFFICIENCY
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODES
EQUIPMENT
ETCHING
HALOGEN COMPOUNDS
INDIUM COMPOUNDS
INDIUM SELENIDES
IODINE COMPOUNDS
IONS
MIXTURES
OPTIMIZATION
OXIDATION
PERFORMANCE
PHOTOANODES
PHOTOCHEMISTRY
PHOTOELECTROCHEMICAL CELLS
SELENIDES
SELENIUM COMPOUNDS
SOLAR EQUIPMENT
SOLUTIONS
STABILITY
SURFACE FINISHING
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS