Structural Color Sensors with Thermal Memory: Measuring Functional Properties of Ti‐Based Nitrides by Eye

Abstract

To ensure safe and reliable operation of materials with high thermal loads, e.g., in turbines or thermal solar collectors, it is key to detect material degradation. Here, a sensor concept providing a direct optical feedback of thermally induced hardness and resistivity changes in transition‐metal‐nitride functional coatings is presented. The sensor concept relies on a lossy Gires–Tournois interferometer configuration using thermally induced detuning of a highly absorbing state in the optical spectrum as feedback. It is demonstrated for the specific case of TiAlN coatings that such detuning is due to a symmetry‐breaking structural phase transition, which is accompanied by the formation of saturated structural colors.

Functional Coatings on High‐Performance Polymer Fibers for Smart Sensing

“…The reflectance minimum observed in the spectra continuously blue‐shifts due to a decrease in refractive index for wavelengths larger than 450 nm. This transition between two reflectance states, characterized by their respective reflectance minima (Figure 2g), is indicative of a second‐order phase transition 21. Here, this transition shown also in Figure 2g occurs at 295 °C.…”

“…An alternative route is structural transformations, i.e., the transition from one crystallographic phase of the material to another. Prominent optical phase change materials (PCM)s are vanadium dioxide17,18 and chalcogenide compounds, such as AgInSbTe19 and GeSbTe (GST),20 but also metastable composites, such as TiAlN are used 21. These materials have been successfully applied as active strong interference coatings,21–23 active metasurfaces,24–27 and metalenses 28,29…”

Absolute Scattering Cross Sections of Titanium Nitride Nanoparticles Determined by Single-Particle Spectroscopy: Implications for Plasmonic Nanoantennas

“…Finally, we compare the experimentally obtained LSPR peak wavelength and absolute σ sca with those obtained by BEM calculations using dielectric functions in the literature. ,− Figure a shows the calculated σ sca spectra. The results obtained for four different dielectric functions are shown. ,, The spectral features, i.e., peak wavelength, intensity, and fwhm, are significantly different between them. Figure b shows the peak wavelength of the calculated spectra as a function of the size together with our experimental results (red open circles).…”

Refractory plasmonics enabling 20% efficient lead-free perovskite solar cells

“…6 38 assuming single-path absorption and unit internal quantum efficiency (IQE). The optical refractive indices and extinction coefficients of Au, MASnI 3 , TiO 2 , Spiro-OMeTAD, ITO, TiN, and ZrN were taken from previously published data [39][40][41][42][43][44][45] . The electrical model was based on the use of the G opt as an input parameter.…”

“…9 can be used to calculate any enhancement in J sc 48 . The COMSOL Multiphysics software package was used with AM 1.5 G as an input power port and a wavelength in the range 100-1300 nm was swept over with 10 nm step size in order to cover the UV, visible, and IR regions to obtain the greatest possible plasmonic enhancement over the whole possible simulated bandwidth because TiN and ZrN nanoparticles have an increasing extinction coefficient in the IR bandwidth 44,45 . The optoelectrical model was applied on a cell surrounded by perfectly matched layers (PMLs) in all directions and periodic boundary conditions (PBCs) in x-y direction.…”