It is essential to study the thermal dewetting behavior of as-deposited nano-films for large scale and high-throughput fabrication. We report here on the nucleation of Au nanostructures onto titanium dioxide (TiO_x) thin films surfaces, which occurred in consecutive steps. First, TiO_x thin films were grown on quartz substrates reactively by e-beam evaporator and then thermally annealed at different temperatures, starting from 300°C to 900°C. Subsequently, a nano-film of Au was deposited on the top of these TiO_x surfaces. The stacked Au / TiO_x samples were post-annealed using muffle furnace at a temperature of 600°C for 1 h, to study the thermal dewetting properties and the controlled growth of the different TiO_x morphologies on the formation of Au nanoparticles (NP) and their plasmonic response. Such dual-structures were characterized accordingly to probe their topological, morphological, structural, and optical properties, by means of x-ray photoelectron spectroscopy, scanning electron microscope, atomic force microscopy, and ultra-violet–visible–near infrared characterization techniques. The thermal dewetting properties were found to improve at high temperatures (>500 ° C), where the Au NP size distribution was found to follow a Gaussian pattern centered around 30 nm. The average surface roughness also increased significantly with respect to the TiO_x dewetting temperature, which is mainly attributed to the porosity of the films. Finally, the absorption peak for Au nanostructures has shown a localized surface plasmon resonance close to 520 nm, along with a broad shoulder peak with a strong tail thereby reflecting the wide distribution of the formed Au NP sizes.

Detailed optoelectronic simulations of thin-film photovoltaic solar cells (PVSCs) with a homogeneous photon-absorber layer made of with CIGS or CZTSSe were carried out to determine the effects of defect density, minority carrier lifetime, doping density, composition (i.e., bandgap energy), and absorber-layer thickness on solar-cell performance. The transfer-matrix method was used to calculate the electron-hole-pair (EHP) generation rate, and a one-dimensional drift-diffusion model was used to determine the EHP recombination rate, open-circuit voltage, short-circuit current density, power-conversion efficiency, and fill factor. Through a comparison of limited experimental data and simulation results, we formulated expressions for the defect density in terms of the composition parameter of either CIGS or CZTSSe. All performance parameters of the thin-films PVSCs were thereby shown to be obtainable from the bulk material-response parameters of the semiconductor, with the influence of surface defects being small enough to be ignored. Furthermore, unrealistic values of the defect density (equivalently, minority carrier lifetime) will deliver unreliable predictions of the solar-cell performance. The derived expressions should guide fellow researchers in simulating the graded-bandgap and quantum-well-based PVSCs.

Relatively low conversion efficiency is the main limitation for realizing the conversion from CO₂ photoreduction to high-value-added chemicals. Herein, we demonstrate that coupling alternating magnetic field (AMF) can significantly enhance the solar-catalyzed CO₂ conversion process. Utilizing NiO / TiO₂ as the experimental photocatalyst, CO₂ could be reduced into CH₄ with the participation of water vapor. The catalytic system presents a high activity that is improved by ∼200 % toward CH₄ production through integrating with AMF. The applied AMF, on one hand, can increase the density of carries by restraining the combination of photogenerated electron-hole pairs. On the other hand, the applied AMF enhances the oxidizability of the catalysts with simulated solar irradiation to boost the oxidation of H₂O to O₂. Further, our examination illuminates that the Ni species serve as the adsorption/mobilization sites of CO₂ to boost the conversion of CO₂ to CH₄ by photogenerated e ⁻ and the H ⁺ produced by H₂O. This strategy paves a new path for boosting photocatalytic CO₂ conversion by integrating AMF into the reaction.

A solar laser pumping approach to achieve both simultaneous and stable multibeam solar laser operation under solar tracking error condition is proposed here. By using a heliostat, solar radiation is firstly redirected to a parabolic mirror, secondarily concentrated by an aspheric lens, and finally absorbed by four Nd:YAG rods within a pump cavity using a homogenizer. Zemax^® and LASCAD^™ analysis demonstrate that four simultaneous and stable 1064-nm continuous-wave solar laser emissions with similar multimode power levels can be achieved even with azimuthal solar tracking errors up to ± 0.5 deg. The variation on the multimode solar laser power of the four rods is significantly reduced from 32.38% and 55.52% without the homogenizer to 0.00% and 0.21% with the homogenizer for ± 0.1 deg and ± 0.2 deg azimuthal solar tracking error, respectively. More importantly, simultaneous and stable TEM₀₀ mode solar laser emissions from the four rods are also numerically attained under solar tracking error condition.

Probabilistic computing with p-bits is a powerful, unique paradigm alternative to classical computing and holds experimental advantages over certain forms of quantum computing. Stochastic nanodevices have been experimentally demonstrated to act as artificial neurons in solving certain problems through probabilistic computing. Still, many open questions about the breadth and size of soluble problems remain. We demonstrate the capability of probabilistic computing made of a stochastic nanodevice network in solving likely NP (non-deterministic polynomial time)-complete number theory problems associated with combinatorial optimization, which can be implemented using a network of optical parametric oscillators. These simulation results show robustness across all problems tested, with great potential to scale to solve substantially larger problems.