Determination of effective diffusion length and saturation current density in silicon solar cells

We have presented an improved method for the determination of both effective diffusion length (Leff) and saturation current density (J01, J02) in silicon solar cells. The modifications overcome the limitation of Taretto et al.'s method [J. Appl. Phys. 93 (2003) 5447] by investigating the effects of series resistance (Rs), shunt resistance (Rsh), high carrier injection contribution and other mechanisms, such as the Poole-Frenkel current, trap assisted tunneling current, etc. on J02 as well as Leff, with the aid of experimental dark current-voltage characteristics. It is found that the high injection contribution has played a key role in J02 and Leff, in contrast to the negligible effect of Rs, Rsh and the other mechanisms. The consideration of both the low and high injection contribution for J02 has resulted in good agreement between the theoretical and experimental Leff, J01, and J02. We have further demonstrated the reliability and significance of the improvements by comparing with the reported Leff results in the literature.