Determination of the diffusion length and surface recombination velocity: two simple methods [for Si solar cells]

The present paper analyzes two new methods for the estimation of the diffusion length (L_d) and surface recombination velocity (S) of crystalline Si solar cells through simple and inexpensive equipment. The first one is based on the behavior of the short-circuit current (J_sc) under rear illumination, as a function of the cell width (d). In a general case, this model allows one to determine L _d and the effective rear S by a numerical fitting. The second method uses solar cells with localized diffusions. A geometry with linear diffusions is considered and the dependence of J_sc with the distance between those diffusions is analyzed by means of a one-dimensional model. The second method is applied to n⁺pp ⁺ solar cells elaborated in the Argentine Atomic Energy Commission (CNEA)