The optical properties derived from our analysis are shown in Figure . These optical dispersion curves provide well-approximated spectral characteristics at, above, and below the bandgap for MAPbBr3. At the scales shown in Figure , the influence of the MA overtones below the bandgap are not depicted well. Figure shows a logarithmic y-axis scale for k, which shows the fine features of the MA overtone anomalous optical dispersion. These data illustrate another advantage of employing spectroscopic ellipsometry and transmission intensity data appended optical dispersion analysis. Reflection mode spectroscopic ellipsometry alone typically does not offer sufficient sensitivity for the derived optical constants below ~10 -3 . However, by including transmission intensity data in the analysis, we improve optical property derivation sensitivity to with a logarithmic y-axis scale to show the sharp band edge transition and MA overtones captured using our experimentally appended optical dispersion data analysis method. ). Here, the MAPbBr3 layer exhibits the greatest peak absorptance above 539 nm followed by FTO and Au. MAPbBr3 exhibits the lowest absorptance below 539 nm; however, there is parasitic absorptance from all other layers at these wavelengths. PSC Design II layer absorptance yields very similar results to PSC Design I, except there is a small peak increase in the MAPbBr3 layer absorptance for Design II below 539 nm. Despite optimizing for MAPbBr3 layer absorptance in the device, the minimal increase in absorptance is due to the fixed thicknesses for all other layers in the design. This is primarily due to the FTO layer exhibiting greater parasitic absorptance above and below the bandgap, with Au contributing next to the most parasitic absorptance below the MAPbBr3 bandgap.