Inorganic perovskite photodetector with chromium interdigitated electrodes is investigated. The active material is a solution processed CsPbI3 synthesized by one step deposition. The α-phase of this material is unstable at room temperature and it converts to the δ-phase at temperatures below 320°C. The stabilization of the α-phase was conducted in nitrogen environment by adding 5% weight ratio of polyethylene oxide to the equimolar mixture of PbI2 and CsI in dimethyl sulfoxide. The absorbance spectrum of the CsPbI3 with polyethylene oxide showed the emergence of a second peak at ∼ 690 nm related to the α-phase in addition to the peak at 420 nm of the δ phase. The peak in the visible range was also observed in the μ-photoluminescence spectrum at 690 nm. The interdigital structure was prepared by photolithography method to deposit 80 nm of chromium interdigitated electrodes on glass substrate with 10 μm channel width. The detector's on/off ratio and the detectivity were calculated from the current voltage curve under 100 mW/cm2 to be 9.64×103 and 9.2×109 Jones respectively.

The need to achieve a uniform distribution of concentrated solar flux in the photovoltaic, thermal or any other receivers is a common problem; therefore, the optical characterization of the concentration system is necessary to determinate the physical characteristics of the receptors. In this work, a parabolic dish concentrator of 1.65x1.65 m2, developed by research from the University of Arizona, is optically characterized under normal operating conditions, also known as environmental conditions that refer to non-controlled conditions as solar radiation, environmental temperature and wind velocity that could affect slightly, by thermal and mechanical efforts, the distribution profiles of the concentrated solar radiation. The set used for the evaluation consisted of the parabolic mirror and Chilled Lambertian Flat Surface installed in the focal point on the optical axis of the mirror. The evaluation was divided into two parts: a theoretical part that consist on using ray tracing simulation and an experimental part that corresponds to image analysis. The used methodology in this work has been stablish in many researches, so this is a reliable method. The global optical error was 2.3 mrad under normal operating conditions.

To understand the potential impacts on both thermal performance and condensation risks of using low-e coatings in buildings, especially in the single-pane sector, in this work, parametric numerical analysis in winter is conducted. Three building glazing models, including the single-pane without low-e coatings (SNL), single-pane with exterior low-e coatings (SEL), and single-pane with interior low-e coatings (SIL), are selected and simulated through COMSOL over a range of outdoor temperature and indoor humidity. The temperature of the interior surface of windows, heat flux through windows, winter U-factor of center-of-glass will be obtained and compared. Additionally, a numerical code is developed in R to compute and plot the condensation temperatures of these three models upon the given indoor humidity levels and simulated surface temperatures. The comprehensive analysis of condensation risks on the glazing inner surface of the three models will be conducted.

This parametric simulation effort indicates an interesting feature for a single-pane window: while the SIL gives a substantially lower U than the SNL, it also corresponds to an increased condensation risk under certain limits of external temperature and indoor humidity levels. Upon the resultant condensation temperatures and thermal performance analysis, we can conclude the parameters of the windowpane property, coating emissivity and placement, local climate, and building interior thermal settings must be taken into account collectively when it comes to adding low-e coatings to single-pane windows.

Fresh water production through sustainable approaches such as solar thermal sources is attracting widespread attention. One of the recently developed approaches aims at utilizing black particles to enhance evaporation and steam generation through efficient photo-thermal conversion process in direct solar thermal desalination systems. Activated carbon serves as one such material for meeting the objectives of freshwater production with negligible increments in cost of the overall system. A series of chemical and physical characterizations were performed to explore the possibility of using activated carbon as a stable carbon source. Optical characterization showed granular activated carbon to have 96.35% solar absorptance and its dispersion in water to have less than 1.5% transmittance (absorbance of 1.85) at 100 mg/L concentration. Outdoor experiments were performed at the University of California-Merced in the month of September (2019), with peak irradiation of 0.8 suns. The comparative measurements showed that the total evaporation enhancement was 38% and 100% for granular activated carbon and activated carbon dispersions, respectively, when compared to pure DI water.

Solar energy can alleviate our dependence on traditional energy sources like coal and petroleum. In this regard, the design and performance of solar absorbers are crucial for capturing energy from sunlight. Specifically, for applications relying on solar-thermal energy conversion, it is desirable to construct solar absorbers using scalable techniques that also allow a variation in optical properties. In this study, we demonstrate the ability to tune the spectral absorptance of nickel-infused nanoporous alumina using a scalable and inexpensive fabrication procedure. With simple variations in the geometry of the nanostructures, we enable broadband absorption with a net solar absorptance of 0.96 and thermal emittance of 0.98 and spectrally-selective absorption with a net solar absorptance of 0.83 and thermal emittance of 0.22. The simple manufacturing techniques presented in this study to generate nanoengineered surfaces can lead to further advancements in solar absorbers with well-controlled and application-specific optical properties.

Design of composite semiconductor nanostructures with proper band alignment for efficient charge separation and carrier transport has been at the center of research for photoelectrochemical water splitting. This work demonstrates the deposition of a NiFe2O4 @Fe2O3 core-shell nanostructured film sensitized with CdS to form a ternary heterojunction for cascade type electron transfer. The hematite nanostructures were grown by hydrothermal approach through dipping into a solution of Nickel Nitrate yielded anchoring of Ni2+ ions on the outer surface. The films were then annealed at 650 0C for the diffusion of Ni2+ ions into the hematite lattice which forms core-shell NiFe2O4 @Fe2O3 heterojunction. The films were further sensitized with CdS nanoparticles deposited by a hydrothermal approach to form the final ternary heterojunction photoanode. Several different nanostructures were grown and the effect of crystal facet tailoring was observed on Ni loading and photoelectrochemical performance. The photoelectrochemical measurements were carried out using a potentiostat under 100 mW/cm2 light source (150W Xenon Lamp) with Pt counter electrode and 0.5 M Na2S and 0.5 M Na2SO3 electrolyte. A current density of 3.47 mA/cm2 was observed at 1.23 V (vs Ag/AgCl). An Applied Bias to Photocurrent Efficiency (ABPE) of 1.8 % photoconversion efficiency was observed using the fabricated electrodes at 0.288V (vs Ag/AgCl).

Electrodynamic screens (EDS) are transparent dielectric films, consisting of embedded, interdigitated parallel conducting electrodes that can be integrated onto the optical surface of a photovoltaic (PV) module or concentrated solar power (CSP) mirror for their self-cleaning function to mitigate the energy yield losses caused by soiling. The EDS film removes dust particles using electrostatic forces thus eliminating the need for water or robotic devices to clean the solar devices. In this paper we report the methods experimented to produce EDS film stacks integrated onto individual PV modules (33 cm x 28 cm) for solar field applications using an industrial vacuum lamination process for the purpose of outdoor testing. Steps taken to optimize the lamination process to provide high optical transparency, resistance against moisture ingress and to withstand dust abrasion are described. The experiments performed to arrive at the optimal curing temperature, curing time, and vacuum pressure maintenance for the lamination process are elaborated. Details on the construction, functionality and operation of the outdoor testing units are provided. Measurements of the optical transmission efficiency (TE) and output power restoration (OPR) of the EDS film stack laminated onto PV modules are presented along with a model for full-scale lamination with an aim for advancing the EDS film technology as a commercially available product.

Perovskite solar cells continue to garner significant attention in the field of photovoltaics. As the optoelectronic properties of the absorbers become better understood, attention has turned to more deeply understanding the contribution of charge transport layers for efficient extraction of carriers. Titanium oxide is known to be an effective electron transport layer (ETL) in planar perovskite solar cells, but it is unlikely to result in the best device performance possible. To investigate the importance of band energy alignment between the electron transport layer and perovskite, we employ numerical modeling as a function of conduction band offset between these layers, interface recombination velocity, and ETL doping levels. Our simulations offer insight into the advantages of energy band alignment and allow us to determine a range of surface recombination velocities and ETL doping densities that will allow us to identify novel high performance ETL materials.