Approximated analytical model for dark and Jsc-Voc characteristics of p(+)-i-n(+) solar cells

The limitations of the superposition principle and of the multiexponential model when applied to p(+)-i-n(+) solar cells are analyzed using a model which allows for the calculation of the J-V characteristics of such cells considering the high injection level in the base. It is shown that a two-exponential model and the superposition principle can be used as a first-order approximation for dark and open-circuit conditions, and that the dark or voltage current cannot be modeled by simple two-exponential expressions.