Light-emitting-diode-based Fourier-transform Spectral Response Measurement System for Photovoltaic Characterizations

A system for measuring the absolute spectral responsivity of solar cells is described. The system uses higher-powered LED arrays that are coupled to an optical light guide that together provide large area illumination. Two different measurement methods were developed and tested using this measurement apparatus. The first method is an individual LED lock-in technique that can be performed over a broad frequency range. The second method, which uses a Fourier transform technique, is based on synchronous multi-frequency optical excitation of all the LEDs, coupled with detection by a spectrum analyser. Schemes for providing light bias using the LEDs during both measurement schemes are discussed. Spectral response measurements using both measurement methods are reported for a variety of solar cells.