Optically selective thin film stacks integrating spectral and angular control of solar energy and thermal radiation 
This project aims to enhance photo-thermal conversion efficiency by improving the optical and thermal stability characteristics of solar-absorbing surfaces. Designing a suitable coating for these surfaces involves a delicate balance between thermal stability, reflectance, and emittance. As an added complication, a coating with a spectral response that switches from highly absorptive in the visible and near-IR range to reflective at longer wavelengths is necessary. Despite extensive prior investigations in this area, several problems remain unsolved - particularly the maintenance of structural integrity and optical response of solar absorbers operating at higher temperatures (>500ºC). The results of the present work are highly relevant to various kinds of high-temperature concentrated solar power (CSP) applications, as well as to thermo-photovoltaic (TPV) systems. Finally, a new algorithm for designing a nearly ideal cermet-based spectrally-selective absorber was developed, enabling the achievement of ???????? > 97%. Although only a few structures are known to absorb solar energy with ???????? in the 97-98% range, their optical performance is degraded in the range 250ºC-500ºC. In the current work, a thermal tolerance of up to 1000°C was accomplished, which appears to be an unprecedented degree of stability at 1000°C for a cermet-based solar absorber.

Four-flux radiative transfer model to determine optical performance of the scattering layer in a multilayer glazing sample from spectrophotometric measurements
The present study proposes a four-flux radiative transfer model to determine the optical performance of the scattering layer in a multilayer glazing sample from spectrophotometric measurements. The model is designed to provide a comprehensive analysis of the optical properties of the scattering layer, taking into account both its reflectance and transmittance characteristics. The model is based on the principle of energy conservation and uses a spectral approach to calculate the distribution of radiative flux within the sample. The proposed approach is particularly useful for investigating the performance of multilayer glazing samples with complex optical properties, and can provide valuable insights into the scattering behavior of the sample.

The model is validated by comparing the simulated results with experimental data obtained from a multilayer glazing sample. The results demonstrate that the model is capable of accurately predicting the optical performance of the scattering layer in the sample. The model is also shown to be highly flexible, and can be adapted to various sample configurations and scattering mechanisms.

Electroluminescence from GeV centers in nanodiamonds
Integration of low-dimensional nanostructures into electronic devices and photonic quantum information technologies has paved the way for the efficient generation of photons, including single photons through photo- and electrical excitation. This process is achieved through the emission of color centers, which can be introduced into the wide band-gap semiconductors by creating defects. The germanium-vacancy (GeV) color center in diamonds has garnered significant attention as a potential qubit for quantum photonics. Nevertheless, electrically controlling and exciting GeV centers have proven challenging, primarily due to the low density of free carriers in doped diamonds. In this study, we have successfully achieved photo- and electrical excitation of GeV centers in a single-crystal nanodiamond, offering a promising avenue for scalable photonic architectures.