Characterization of the diffusion length of solar cells in space has been widely
studied using various methods, but few studies have focused on a fast, simple way to
obtain the quantified diffusion length distribution on a silicon wafer. In this
work, we present two different facile methods of doing this by fitting
photoluminescence images taken in two different wavelength ranges or from different
sides. These methods, which are based on measuring the ratio of two
photoluminescence images, yield absolute values of the diffusion length and are less
sensitive to the inhomogeneity of the incident laser beam. A theoretical simulation
and experimental demonstration of this method are presented. The diffusion length
distributions on a polycrystalline silicon wafer obtained by the two methods show
good agreement.