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This technical report documents a particular error in efficiency measurements of triple-absorber concentrator solar cells caused by incorrect spectral irradiance-specifically, one that occurs when the irradiance from unfiltered, pulsed xenon solar simulators into a GaInAs bottom subcell is too high. For cells designed so that the light-generated photocurrents in the three subcells are nearly equal, this condition can cause a large increase in the measured fill factor, which, in turn, causes a significant artificial increase in the efficiency. The error is readily apparent when the data under concentration are compared to measurements with correctly balanced photocurrents, and manifests itself as discontinuities in plots of fill factor and efficiency versus concentration ratio. In this work, we simulate the magnitudes and effects of this error with a device-level model of two concentrator cell designs, and demonstrate how a new Spectrolab, Inc., Model 460 Tunable-High Intensity Pulsed Solar Simulator (T-HIPSS) can mitigate the error. Although in this work the error has been identified in GaInAs bottom subcells, increasing the photocurrent in any subcell will produce similar errors, regardless of the chemical composition.

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We describe the successful construction of a 12.1" 800x600 microencapsulated electrophoretic active matrix display incorporating an a-Si thin film transistor backplane. The display exhibits a print-on-paper-like appearance (high reflectance, high contrast ratio and wide viewing angle) and grayscale at 83 DPI, and demonstrates the material's compatibility with commercial a-Si TFT LCD backplanes.

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