Optimization of TiN-based ultra-flexible materials for photothermal and solar harvesting applications

Abstract

Abstract We propose a theoretical model to investigate photothermal heating of ultra-flexible metamaterials, which are obtained by randomly mixing TiN nanoparticles in polydimethylsiloxane (PDMS). Due to the plasmonic properties of TiN nanoparticles, incident light can be perfectly absorbed in a broadband range (300-3000 nm) to generate heat within these metamaterials. Under irradiation of an 808 nm near-infrared laser with different intensities, our predicted temperature rises as a function of time agree well with recent experimental data. For a given laser intensity, the temperature rise varies non-monotonically with the concentration of TiN nanoparticles. Increasing the TiN concentration leads to a decrease in the heating process since the thermal conductivity grows. A small TiN concentration significantly reduces the absorbed energy and, thus, the system is less heated. When we apply this model to solar heating, we find that the temperature rise is no longer non-monotonic, and the heating efficiency is much lower than in the laser case. Our studies would provide good guidance for future experimental studies on the photothermal heating of broadband perfect absorbers.