Correlation of the photoelectrochemistry of the amorphous hydrogenated silicon/methanol interface with bulk semiconductor properties
Semiconductor/liquid junctions derived from 0.5 /sigma phi/m thick films of amorphous hydrogenated silicon, a-Si:H, have been investigated in CH/sub 3/OH solvent. The a-Si:H films consist of a weakly doped n-type layer ove a 200A n/sup +/-a-Si:H layer on a stainless-steel substrate. The low series resistance and high ratio of minority carrier collection length to film thickness in this arrangement allows a study of the properties of semiconductor/liquid interfaces with minimal interference from bulk resistance losses. We find that a-Si:H anodes in 0.02M ferrocene, FeCp/sub 2//0.5 mM FeCp/sub 2//sup +//1.5M LiClO/sub 4//CH/sub 3/OH solutions exhibit poor short-circuit quantum yields and low fill factors with 632.8 nm irradiation, but that these junctions display internal quantum yields of close to unity and high fill factors with short wavelength (lambda < 450 nm) irradiation. Photons absorbed within a distance comparable to the minority carrier collection length are efficiently collected, and the fill factors and quantum yields under such conditions are insensitive to increases in photocurrent density over a range of 0.1-2 mA/cm/sup 2/. Solar-simulated irradiation (88 mW/cm/sup 2/) from a ELH-type tungsten-halogen lamp in the a-Si:H/0.02M FeCp/sub 2//0.5 mM FeCp/sub 2//sup +//1.5M LiClO/sub 4//CH/sub 3/OH system yields open-circuit photovoltages of 0.75-0.85V, shortcircuit photocurrents of 6-7 mA/cm/sup 2/, and photoelectrode efficiencies for conversion of light to electricity of 2.7%-3.3%. Photovoltages with the acetylferrocene /sup +/0/ redox system are among the highest reported for any a-Si:H surface barrier system, and can exceed 0.85V under AM1 illumination conditions. Variation in the redox potential of the solution leads to changes in open-circuit photovoltage in accord with theory, and does not yield evidence for pinning of the a-Si:H Fermi level by interface states or by surface oxides over the potential range investigated.
- Research Organization:
- Department of Chemistry, Stanford University, Stanford, California
- OSTI ID:
- 5637493
- Journal Information:
- J. Electrochem. Soc.; (United States), Vol. 131:12
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN
ELECTRIC CONDUCTIVITY
METHANOL
PHOTOELECTROCHEMICAL CELLS
PHOTOCHEMISTRY
SEMICONDUCTOR JUNCTIONS
SILICON
HYDROGENATION
AMORPHOUS STATE
CHEMICAL REACTION KINETICS
CHLORATES
CORRELATIONS
FABRICATION
INTERFACES
IRON COMPOUNDS
LITHIUM COMPOUNDS
PHOTOCHEMICAL REACTIONS
QUANTUM EFFICIENCY
STAINLESS STEELS
ALCOHOLS
ALKALI METAL COMPOUNDS
ALLOYS
CHEMICAL REACTIONS
CHEMISTRY
CHLORINE COMPOUNDS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
EFFICIENCY
ELECTRICAL PROPERTIES
ELECTROCHEMICAL CELLS
ELEMENTS
EQUIPMENT
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
IRON ALLOYS
IRON BASE ALLOYS
JUNCTIONS
KINETICS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
SEMIMETALS
SOLAR EQUIPMENT
STEELS
TRANSITION ELEMENT COMPOUNDS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400500 - Photochemistry