Optimizing the bandgap energy for a perovskite cell typically requires the complex refractive index,
which are obtained from spectroscopic ellipsometry measurements. While these measurements are
usually available for a few discrete bandgap energies, it is desired to have them in continuous range to
find the optimal bandgap energy. We propose a new method for generating the complex refractive
index, based on the interpolation of a few measured data sets. The Forouhi-Bloomer model is used to fit
the measured data. Then a linear regression is applied to the fit parameters with respect to the bandgap
energy. From the interpolated parameters, the refractive index curve of perovskite with any desired
bandgap energy is finally reconstructed. We validated our method by simulating the absorptance of a
single junction perovskite cell and a perovskite/silicon tandem cell, showing that our method can
accurately model the refractive index.
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