Semi-analytical technique for the design of disordered coatings with tailored optical properties

TL;DR

This paper develops a semi-analytical method to efficiently design disordered coatings with tailored optical properties across the full spectrum from visible to IR, addressing limitations of existing analytical models.

Contribution

It introduces a semi-analytical approach based on analyzing the applicability of Kubelka-Munk and four-flux methods for broad-spectrum coating design.

Findings

Semi-analytical method reduces computational cost significantly.

Existing analytical models are limited to specific spectral ranges.

Proposed method improves accuracy over traditional models for broad-spectrum applications.

Abstract

Disordered media coatings are finding increasing use in applications such as day-time radiative cooling paints and solar thermal absorber plate coatings which require tailored optical properties over a broad spectrum ranging from visible to far-IR wavelengths. Both monodisperse and polydisperse configurations with thickness of coatings up to 500 micrometer are currently being explored for use in these applications. In such cases it becomes increasingly important to explore utility of analytical and semi-analytical methods for design of such coatings to help reduce the computational cost and time for design. While well-known analytical methods such as Kubelka-Munk and four-flux theory have previously been used for analysis of disordered coatings, analysis of their utility has so far in literature been restricted to either solar spectrum or IR but not simultaneously over the combined spectrum as required for the above applications. In this work, we have analysed the applicability of these two analytical methods for such coatings over the entire wavelength range from visible to IR, and based on observed deviation from exact numerical simulation we propose a semi-analytical technique to aid in the design of these coatings with significant computational cost savings.