Analysis of the photocurrent decay (PCD) method for measuring minority-carrier lifetime in solar cells

A three-dimensional analysis of the laser-beam induced current method to measure the minority-carrier lifetime τ in solar cells is given. In this method the beam is incident normally at a stationary point on the front cell surface, and the lifetime is found by rapdily switching it off and studying the resulting current decay. Expressions for this decay are derived for both thick and thin solar cells, the latter with or without a back surface field (BSF). For thin cells, the most interesting in practice, the current decays according to for ordinary cells and for ideal BSF cells where is the minority-carrier diffusion coefficient and the cell thickness.