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Since 1988, researchers at Sandia's photovoltaics
departments have been conducting in-house cell
processing research and supporting contracted research to advance
the technology of silicon (Si) solar cells, both to improve
performance and to reduce cost. Our world-class cell measurement
laboratory performs NIST-traceable measurement of one-sun and
multi-sun illuminated current vs. voltage (IV), dark-IV, absolute
spectral response, hemispherical spectral reflectance, and more.
When combined with numerical simulation software, Sandia researchers
are able to glean important information about the performance-limiting
mechanisms of both laboratory and commercial Si solar cells.
NIST-traceable
illuminated current vs. voltage measurement as a function of
temperature.
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Sandia-developed
cell characterization tools, such as long-wavelength
internal quantum efficiency (IQE) analysis, enables extraction
of both optical and electronic performance parameters. Light
beam induced current (LBIC) allows cell spatial performance
mapping and infrared (IR)-camera detection permits detection
of regions of high shunt currents.
Internal and External Quantum Efficiency,
Total and Front-Surface Reflectance as a function of wavelength.
Sandia's
researchers are available to apply their years
of experience in measurement, design, and performance analysis
using numerical simulation of PV cells to support Technology
Pathway Partnerships for the Solar America Initiative.
Sandia
National Laboratories will conduct an extensive
series of performance measurements on solar cells fabricated
by the SAI partnerships. The results of these extremely accurate
measurements will be used in various solar cell device modeling
codes to extract relevant material parameters, both electrical
and optical, which limit the energy conversion efficiency of
the devices. Then, discussions can be held to determine how
to best vary and optimize design and process parameters to achieve
greater performance.
New
devices could be fabricated using a design of experiments approach
to explore the parameter space of relevant process factors.
Sandia has all the capabilities needed to design, plan and analyze
the results of these statistically designed experiments. The
new devices will undergo the same performance measurement and
analysis, validating the models and predicting an optimum set
of process and design parameters. The improvements can be iterative,
resulting in ever-increasing levels of performance.
Response surface of cell performance
vs. power and pressure of SiN deposition.
| Equipment available for cell performance
measurements, failure diagnostics, calibration of reference
cells and irradiance sensors: |
1.
Current vs. voltage measurements per ASTM standards,
one-sun and concentration to 1000X.
2. Spectral response, internal quantum efficiency, 300
to 2400 nm.
3. 2-D LBIC scanning at 4 wavelengths.
4. Spectral reflectance and transmittance to 2400 nm.
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