A simple procedure to analyze rear-surface internal quantum efficiency

Many crystalline-silicon solar cells have grids on both surfaces that allow spectral measurements with illumination of the rear surface. Rear-surface spectral response is very sensitive to the bulk diffusion length and the back-surface recombination velocity (L and S), and in many cases can provide information on these parameters that is not obtainable from analysis of front-surface spectral data. This paper reports a new procedure for analyzing rear-surface spectral data that uses a simple linear fit of rear-surface internal quantum efficiency versus photon absorption length. The paper describes the theoretical basis and limits of the procedure. The application of the procedure to solar cells with different back surfaces is also described.