To further maximize MAPbBr3 layer absorptance and minimize parasitic absorptance by non-active layers in the PSC device, we optimize MAPbBr3 layer absorptance while permitting changes to FTO and Au layer thicknesses. The impact of permitting the parameterization of just these three layers in the device is shown in Figure . Here, a noticeable increase in peak MAPbBr3 absorptance below the bandgap is observed along with a considerable decrease in parasitic absorptance across all wavelengths above 400 nm (the arbitrarily selected target wavelength cutoff of the MAPbBr3 optimization for the PSC design). We evaluated the performance of the PSC device with parameterization of all layer thicknesses; however, little improvement was observed between PSC Design III and an all-layer thickness parameterization design (not shown). Overall, PSC Design III suggests it is possible to carry out PSC design iterations constrained by physical thickness limits of the non-active layers, for instance, in order to maintain electronic performance of the contact and electron/hole transport layers while optimizing overall optical performance.