Flash quantum efficiency measurements for multi-junction solar cells

Flash Quantum Efficiency — a technique used to simultaneously measure full spectrum external quantum efficiency (EQE), Reflectance (R), and Transmittance (T), has been introduced in two prior publications [1,2]. The method uses a novel architecture to simultaneously modulate a bank of solid state lightsources and measure, in real time, the cell response to each wavelength. In this work we extend it to include two additional capabilities-automated spatial mapping and multi-junction measurements. Mapping throughput of 2400 sites per hour is demonstrated on single crystal silicon cells with a signal to noise ratio that is significantly higher than conventional QE. New inverted metamorphic cells are also used to develop and demonstrate a multi-junction FlashQE technique with total acquisition time of less than four seconds per triple-junction cell.