Modeling the optical properties of Morpho-inspired thin-film interference filters on structured surfaces

Abstract

We present a method for modeling the optical properties of interference layer systems on structured surfaces as used in the MorphoColor technology for coloring integrated photovoltaic modules. By combining a microfacet-based bidirectional scattering distribution function model with a transfer matrix formalism, we can simulate the spectrally resolved reflection and transmission properties of the system in good agreement with measurement data. To consider the MorphoColor technology in an overall optical system and compare the application on the front side of the module glass with the application in the composite, the model is additionally combined with a formalism called Optical Properties of Textured Optical Sheets. For a representative illumination and viewing geometry, the composite configuration causes a significantly improved homogeneity of the color appearance.

Optimal Design of Multilayer Optical Color Filters for Building‐Integrated Photovoltaic (BIPV) Applications

“…A probable explanation for this deviation is that GenPro4 considers a uniform layer growth across the textured surface. The growth of the layers on such surfaces does not follow this trend, as explained by Wessels, et al [ 34 ] and reported by other studies that analyzed this trend on non‐flat surfaces. [ 41,42 ] So, for larger optical paths, the deviation between the predicted behavior differed more than for the case of normal incidence.…”

“…As mentioned before, depositing the filter on textured surfaces also improves color stability, as demonstrated by A. Wessels et al [ 34 ]…”

“…As mentioned before, depositing the filter on textured surfaces also improves color stability, as demonstrated by A. Wessels et al [34] Utilization of the HCL color space and the ΔE Ã 00 color difference formula can help to analyze how texturization improves color stability. Figure 5a shows the HCL coordinates of the color perceived at different AoOs for the colored mini-PV module shown in Figure 4a.…”

“…Analysis of other structures in which the CF can be deposited is outside of the scope of this study, as some of them require specific and complex additional optical modeling to accurately predict the growth of the CF layers and the correct optical paths resulting from their manufacturing. One example of the additional modeling required can be found in the work by Wessels et al [34] Figure 8 summarizes the effect that texturing has on the perceived color for the same combination of thicknesses (SiO 2 = 80 nm and SiN X = 80 nm and p = 10). Structures 2 and 3, which feature rounded grooves at the front side of the glass and flat (Figure 8b) or random texture (see Supporting Information) at the rear side of the glass, respectively, only slightly ameliorate color stability at different AoOs.…”

“…Analysis of other structures in which the CF can be deposited is outside of the scope of this study, as some of them require specific and complex additional optical modeling to accurately predict the growth of the CF layers and the correct optical paths resulting from their manufacturing. One example of the additional modeling required can be found in the work by Wessels et al [ 34 ]…”