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Transient I-V Measurement Set-up for Photovoltaic Laser Power Converters under Monochromatic Irradiance
: Reichmuth, S.K.; Helmers, H.; Garza, C.E.; Vahle, D.; Boer, M. de; Stevens, L.; Mundus, M.; Helmers, H.; Bett, A.W.; Siefer, G.
A new I-V measurement set-up called LaserSim has been developed for photovoltaic laser power converters photovoltaic cells optimized for monochromatic artificial light - providing irradiances of up to 89 W/cm². The evaluation of the set-up and first I-V curve and efficiency measurements are presented. Similar to flash simulators used for I-V characterization of solar cells, the LaserSim is using transient measurement routines to avoid an influence of heating of the samples during measurement. An excellent light uniformity in the designated test area was realized. A beam sampler allows for in-situ irradiance determination while recording I-V data. This is mandatory for characterization of devices showing a non-linear behavior of short circuit current with irradiance. Efficiency values under monochromatic light at 809 nm have been measured for a single junction GaAs cell (55.6 %) and a dual-junction GaAs device (53.5 %).