Abstract:
The possibility of application of a semiempirical expression, which specifies the principal saturation currents of a $p$–$n$ junction, in calculation of the efficiency of multijunction solar cells is examined. This expression relies on the following current invariants obtained earlier: $J_{Z1}$ for saturation current $J_{01}$ (ideality factor $A=1$) and $J_{Z2}$ for saturation current $J_{02}(A=2)$. It is demonstrated that the use of $J_{Z1}$ and $J_{Z2}$ provides an opportunity to enhance the accuracy of calculations considerably relative to the standard techniques based on the Shockley–Queisser solar cell model. The introduction of saturation current $J_{02}$ into calculations is a novel feature. It is demonstrated that the addition of $J_{02}$ is a prerequisite to realistic estimation of the efficiency of multijunction solar cells with more than two subcells.
Keywords:solar cell, saturation current, current invariant, efficiency.
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