Plasmonic properties of electrochromic doped metal oxides investigated through Kubelka Munk formalism

TL;DR

This paper explores the use of the Kubelka Munk model to accurately characterize the plasmonic and electrochromic properties of doped metal oxide particles, aiding in the development of smart window materials.

Contribution

It derives and experimentally verifies an analytical model for small particles, enhancing optical property characterization of plasmonic doped metal oxides.

Findings

Validated the analytical model for small particles

Demonstrated the application of dilution method for plasmonic verification

Enhanced understanding of optical properties of doped metal oxides

Abstract

Materials with broadband tunable optical properties are looked for in smart windows applications. Doped metal oxides presenting dual band visible (VIS) near infrared (NIR) electrochromic properties can be used for solving such a challenge, and their accurate optical characterization is therefore of prime importance. Kubelka Munk model is a state of the art way to optically quantify the absorption properties of materials and is occasionally applied to plasmonic materials, even if great care should be taken to meet the formalism hypotheses. In the present work, Kubelka Munk theory is discussed in the context of particles of indium tin oxide and molybdenum tungsten oxide formulations that are used as single NIR and both VIS and NIR active advanced electrochromic materials, respectively. An analytical model is derived for particles of much smaller dimensions than the incident wavelength and is experimentally verified. A dilution method is applied to verify the plasmonic characteristics of the particles. This study is key for efficient characterization of optical properties of metal oxides, and plasmonic materials in general, from diffuse reflectance measurements.