The optical performance of a given PSC in practice also includes the angle of the incident of light, which will be strongly influenced by the design. Figure show the total absorptance for the respective PSC designs from 0-90° AOI as a function of wavelength, where 0° represents the incident light normal to the device interface. PSC Designs I and II show very similar AOI performance with a noticeable increase in parasitic absorptance below the band edge at ~50° AOI. This increase in parasitic optical absorptance originates as a result of each individual layer material optical properties and is a direct artifact of the PSC device design (layer thicknesses of the nonactive layers within the PSC). PSC Design III in Figure shows no such spectral artifact at ~50° AOI and an improvement in device optical absorptance at and below the MAPbBr3 bandgap as a function of AOI, which further demonstrates the need to optimize the optical performance of selected material layers in a given PSC. By selectively expanding the design optimization, Design III shows that the MAPbBr3 layer absorptance can be strategically improved, parasitic absorptance by the other device layers can be decreased at all wavelengths, and total device optical performance can be refined up to high angles of incidence.