9th November 2011, Belfast, UK: With demand for photovoltaic panels more than doubling year on year, manufacturers are under pressure to increase solar cell efficiency, improve production yields, and build capacity. Now, a joint team from the Department of Electrical and Computer Engineering at the National University of Singapore has demonstrated a novel technique to non-destructively test silicon wafer solar cells.
In their research, PhD student Matthew Peloso and his colleagues are developing methods of characterizing solar cells based on luminescence detection and relating this to the electrical properties of the devices. They use an Andor Luca-R Electron Multiplying CCD (EMCCD) camera to image the solar cells and believe the process may be integrated into the production process, helping manufacturers to improve yields and ramp up volume.
“We have shown that by controlling the applied voltage inducing electroluminescence in solar cells, the observed spectrum of emitted radiation may be used to identify particular performance-reducing defects”, says Peloso. “Detection of these changes can be used to understand the electrical properties of defects in the wafers and, potentially, to study their origin, which may lead to lower-cost, higher-quality materials for production. Moreover, the method has proven useful at the module as well as the cell level. We demonstrated that breakdown luminescence - which we believe is associated with metallic impurities - does not show a one-to-one relationship with other defect related luminescence signals detected at energies below the silicon bandgap. Interestingly, certain defects did not lead to electrical shunts, which may cause irreversible destruction of PV modules and cells.
“We chose the Andor Luca-R EMCCD camera because of its high red to NIR sensitivity and linear response to intensities, which allows more quantitative data acquisition. The electron multiplying (EM) gain control allowed us to enhance signal to noise when necessary, although we operated much of the time in non-EM gain mode. The Luca-R also provides a good balance of attractive features, including the ability to achieve high integration times and binning, at a lower price compared to other available scientific cameras, such as deep depletion CCD cameras”, he adds.
Dr Colin Coates, Imaging Product Manager at Andor, comments that “Andor’s Luca R makes ultrasensitive EMCCD technology available to this price sensitive application. The megapixel format, enhanced red sensitivity and ability to apply EM gain as required renders Luca R an extremely attractive and versatile camera for characterisation and in-line testing of photovoltaics by electro and photoluminescence.”
Andor’s scientific cameras encompass a wide range of high performance CMOS, CCD, ICCD and EMCCD detectors. To learn more about the Luca camera series and their use in microscopy, please visit the Andor website (http://www.andor.com).
For a high resolution version of the image above, which shows an entire solar module (1000 x 450 mm) imaged with the Andor Luca-R Electron Multiplying CCD (EMCCD) camera, either click on the image, use this link, or contact John Waite at Catalyst Limited.
Reference
Peloso, M. P., Chaturvedi, P., Wurfel, P., Hoex, B. and Aberle, A. G. “Observations on the Spectral Characteristics of Defect Luminescence of Silicon Wafer Solar Cells,” Photovoltaic Specialists Conference (PVSC), 2714-2717 (2010) 35th IEEE
About Andor Technology
Andor is a world leader in Scientific Imaging, Spectroscopy Solutions and Microscopy Systems. Established in 1989 from Queen’s University in Belfast, Northern Ireland, Andor Technology now employs over 300 people in 16 offices worldwide, distributing its portfolio of over 80 products to 10,000 customers in 55 countries.
Using the latest cutting edge technologies, Andor designs and manufactures robust, high performance instruments allowing scientists around the world to measure light down to a single photon and capture events occurring within 1 billionth of a second. This unique capability is helping them push back the boundaries of knowledge from nano-scale to universe-scale level in fields as diverse as drug discovery, new material development and analysis, medical diagnosis, food quality control, art restoration, astronomy and solar energy research.
More information about Andor Technology PLC (LSE: AND) is available at the company’s website (www.andor.com).
For further information, please contact Andor Technology direct or their marketing agency, Catalyst Communications.
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