Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells: Preprint

Conference · Mon May 01 00:00:00 EDT 2006

DOI:https://doi.org/10.1109/WCPEC.2006.279780· OSTI ID:891538

Jiang, C -S; Moutinho, H R; Al-Jassim, M M; Kazmerski, L L; Yan, B; Owens, J M; Yang, J; Guha, S

Local open-circuit voltage (Voc) distributions on amorphous and nanocrystalline mixed-phase silicon solar cells were measured using a scanning Kelvin probe microscope (SKPM) on the p layer of an n-i-p structure without the top ITO contact. During the measurement, the sample was illuminated with a laser beam that was used for the atomic force microscopy (AFM). Therefore, the surface potential measured by SKPM is the sum of the local Voc and the difference in workfunction between the p layer and the AFM tip. Comparing the SKPM and AFM images, we find that nanocrystallites aggregate in the amorphous matrix with an aggregation size of {approx}0.5 ..mu..m in diameter, where many nanometer-size grains are clustered. The Voc distribution shows valleys in the nanocrystalline aggregation area. The transition from low to high Voc regions is a gradual change within a distance of about 1 ..mu..m. The minimum Voc value in the nanocrystalline clusters in the mixed-phase region is larger than the Voc of a nc-Si:H single-phase solar cell. These results could be due to lateral photo-charge redistribution between the two phases. We have also carried out local Voc measurements on mixed-phase SiGe:H alloy solar cells. The magnitudes of Voc in the amorphous and nanocrystalline regions are consistent with the J-V measurements.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO.
• Sponsoring Organization: USDOE
• DOE Contract Number: AC36-99GO10337
• OSTI ID: 891538
• Report Number(s): NREL/CP-520-39882
• Conference Information: Presented at the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion (WCPEC-4), 7-12 May 2006, Waikoloa, Hawaii
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ALLOYS
AMORPHOUS
ATOMIC FORCE MICROSCOPY
ATOMIC FORCE MICROSCOPY (AFM)
DISTRIBUTION
ENERGY CONVERSION
LASERS
MICROSCOPES
NANOCRYSTALINE
OPEN-CIRCUIT VOLTAGE
ORGANIC COMPOUNDS
PROBES
PV
SCANNING KELVIN PROBE MICROSCOPE (SKPM)
SILICON SOLAR CELLS
SOLAR CELLS
Solar Energy - Photovoltaics
SURFACE POTENTIAL
VOLATILE MATTER