Energetics of p/n photoelectrolysis cells
The energetics of p/n photoelectrochemical cells, containing simultaneously illuminated p-type photocathodes and n-type photoanodes, have been investigated by using appropriate combinations of n-WSe/sub 2/, n-MoSe/sub 2/, n-WS/sub 2/, n-TiO/sub 2/, p-InP, p-GaP, and p-Si semiconductor electrodes. The open-circuit photovoltages (E/sub OCV/) of the p/n cells were measured as a function of the redox reactions in the cell and as function of light intensity. For many semiconductor electrode combinations, the sum of E/sub OVC/ plus the standard cell voltage for the net cell reaction (..delta..E/sup 0/) was found to be constant for a given pair of n- and p-type electrodes at a given light intensity. This constancy was shown to be equivalent to the constancy of the sum of the band bending in the semiconductor depletion layers and the sum of the electrode overvoltages. These results are explained by movement of the semiconductor band edges with changes in the redox reactions that occur at the semiconductor electrode. If special care is taken to produce semiconductor electrodes that do not show surface charging effects, E/sub OVC/ was found to be independent of the redox reaction. This is the expected behavior for pinned band edges. The dependence of E/sub OVC/ on light intensity for p-InP/n-MoSe/sub 2/ cells was either about 60 mV or about 130 mV per decade increase in light intensity. The latter value occurred when both the p-InP and n-MoSe/sub 2/ band edges were pinned, while the former value occurred when only the p-InP band edge was pinned. These conditions for band-edge pinning depended upon light intensity and the nature of the electrolyte. 20 references, 9 figures, 2 tables.
- Research Organization:
- Solar Energy Research Inst., Golden, CO
- OSTI ID:
- 5984735
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:15; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140501 -- Solar Energy Conversion-- Photovoltaic Conversion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
400500* -- Photochemistry
BAND THEORY
CHALCOGENIDES
CHEMICAL REACTIONS
CONVERSION
DATA
DIRECT ENERGY CONVERSION
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTROLYSIS
ELECTROLYTES
ELECTROLYTIC CELLS
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY CONVERSION
EQUIPMENT
EXPERIMENTAL DATA
GALLIUM COMPOUNDS
GALLIUM PHOSPHIDES
INDIUM COMPOUNDS
INDIUM PHOSPHIDES
INFORMATION
JUNCTIONS
LYSIS
MOLYBDENUM COMPOUNDS
MOLYBDENUM SELENIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
P-N JUNCTIONS
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOELECTROCHEMICAL CELLS
PHOTOELECTROLYSIS
PHOTOELECTROLYTIC CELLS
PHOTOVOLTAIC CONVERSION
PNICTIDES
REDOX REACTIONS
REFRACTORY METAL COMPOUNDS
SELENIDES
SELENIUM COMPOUNDS
SEMICONDUCTOR JUNCTIONS
SEMIMETALS
SILICON
SOLAR ENERGY CONVERSION
SOLAR EQUIPMENT
SULFIDES
SULFUR COMPOUNDS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN SELENIDES
TUNGSTEN SULFIDES