Researchers at the University of California, Davis (“UC Davis”) have developed an optical absorber/emitter for thermophotovoltaics application with a tunable emission wavelength.

Researchers at the University of California, Davis have developed an approach to generating mechanical power from the earth's ambient thermal radiation using a Stirling engine.

Brief description not available

      Goniophotometers measure the luminance distribution of light emitted or reflected from a point in space or a material sample. Increasingly there is a need for such measurements in real-time, and in real-world situations, for example, for daylight monitoring or harvesting in commercial and residential buildings, design and optimization of greenhouses, and testing laser and display components for AR/VR and autonomous vehicles, to name a few. However, current goniophotometers are ill-suited for real-time measurements; mechanical scanning goniophotometers have a large form factor and slow acquisition times. Parallel goniophotometers take faster measurements but suffer from complexity, expense, and limited angular view ranges (dioptric angular mapping systems) or strict form factor and sample positioning requirements (catadioptric angular mapping systems). Overall, current goniophotometers are therefore limited to in-lab environments.      To overcome these challenges, UC Berkeley researchers have invented an optical sensor  for parallel goniophotometry that is compact, cost-effective, and capable of real-time daylight monitoring. The novel optical design addresses key size and flexibility constraints of current state-of-the-art catadioptric angular mapping systems, while maximizing the view angle measurement at 90°. This camera-like, angular mapping device could be deployed at many points within a building to measure reflected light from fenestrations, in agricultural greenhouses or solar farms for real-time monitoring, and in any industry benefitting from real-time daylight data.

Researchers at the University of California, Davis have developed a green technology designed for the efficient storage and discharge of heat energy sourced from intermittent green energy supplies.

Traditionally, land can be used for either crop growth or energy production. This technology optimizes the efficiency of land use by combining both. Researchers at the University of California, Davis have developed solar cell designs that absorb only specific solar photons (> 2.2 eV) to create electricity, while letting through beneficial light (< 2.2 eV) for efficient crop growth.

Many non-traditional energy sources, such as solar panels, fuel cells, and batteries, supply direct-current (DC) power. This has led to development of DC power systems for a number of applications since conversion to alternating-current (AC) can be eliminated. For example, DC distribution is now used for computer data centers, office buildings, and ship power and propulsion. Though the source, loads, and other components in a DC power system are well understood, there may be interest in innovation with respect to protection schemes since DC systems do not have a zero crossing in its current, and circuit breakers are unable to open up a faulted component without sustaining an arc.

Researchers at the University of California, Davis, have developed an improved redox flow battery (RFB) for intermittent renewable energy applications such as wind, solar, and tidal. The device provides high-density energy storage and transfer without losing capacity over time and frequent replacement as with traditional lithium batteries.

Brief description not available

Brief description not available

Photosynthetic organisms use “soft” macromolecular assemblies for light absorption and concentration of electronic excitation energy. These generally work via an optically inactive protein-based backbone that acts as a host matrix for an array of light-harvesting pigment molecules. The pigments are organized in space such that excited states can migrate between molecules, ultimately delivering the energy to the reaction center. 

Large format active or deformable mirrors can enable optical applications that are difficult to achieve with more conventional-sized deformable mirrors. In particular, adaptive secondary mirrors (ASMs) can be integrated into telescopes and provide adaptive optics corrections. However, making facesheets for ASMs is challenging. Current facesheet fabrication processes are costly and risky. Hot forming approaches for forming curved facesheets have been developed, but these methods typically require a mold for the facesheet to slump into.

Hydrogen from sustainable/renewable inputs shows promise as a decarbonized energy source. Hydrogen can be produced from a liquid electrolyte (e.g., water) through a variety of sunlight-based processes, including low/high-temperature electrolysis (e.g., steam electrolysis), photoelectrochemical (PEC), and solar thermochemical (STC). Temperature-based electrolysis systems using solar electricity are generally more complex and less solar-to-hydrogen efficient than PEC and STC. Water-splitting by PEC uses functional materials and leverages sunlight-driven electron-hole pairs to produce hydrogen and oxygen in two half reactions. STC water-splitting uses a series of consecutive chemical reactions and absorbed heat from sunlight to generate hydrogen and oxygen in two full reactions. Generation of hydrogen bubbles at the electrode-electrolyte interface obstruct the propagation of sunlight to functional or catalytic interfaces which limits the cell performance.

Renewable energy sources such as solar photovoltaics (PV) and wind turbines are used for clean power generation to address the ever-increasing energy consumption. With large-scale integration of renewables, battery storage becomes essential in the grid to meet supply-demand volatility. In these scenarios, direct current (DC) grids offer multiple benefits over alternating current (AC) grids such as, improved efficiency, controllability, reliability and reduced cost. Isolated voltage boost/step-up DC-DC converters are used for interfacing PV and wind energy sources with DC grids and DC-DC converters serve such applications and environments. Existing DC-DC converter designs have known weaknesses. For example, shunt-resonant converter capacitors require a dedicated charging interval in every switching half-cycle, which does not contribute towards energy transfer and results in duty-cycle loss. Since the shunt-resonant capacitor is designed to hold resonant energy sufficient for a rated current condition, resonant energy is fixed for all loading conditions. At reduced loading, reduced resonant energy is sufficient but shunt-configuration has no means to achieve this control. Although this may be mitigated by using two additional switches, this arrangement leads to increased losses and cost. At reduced loading, duty-cycle loss increases significantly because the reduced current results in longer capacitor charging time. This severely restricts the operation range of converter. Smooth current commutation and zero-current-switching (ZCS) are also lost at overload conditions since the capacitor is designed for rated-current condition. The shunt-resonant capacitor is expected to hold its voltage/energy during the operating mode when input inductor charges. However, a leakage path exists through the transformer winding parasitics, which results in capacitor discharge. As a result, the capacitor energy must be overrated to compensate for this loss, which further aggravates all of the aforementioned issues. In another example, series-resonant capacitors must also be charged to a voltage higher than the reflected voltage across the transformer-primary. Peak voltage-rating of primary-side components (e.g., switches and input inductor) is also increased. Series-resonant capacitor also transfers energy to the output during the time interval when resonant current commutation occurs, which requires using capacitors having a higher rating. At reduced loading, the series-resonant capacitor does not have enough voltage to satisfy the resonant condition. Switching frequency may be used as an additional control parameter without using extra switches. Reduction in switching frequency results in increased charging time and hence, higher voltage, while ripple content increases and requires larger filters due to varying switching frequency. Overall, while traditional DC-DC converters like the aforementioned meets some requirements, it may be desirable to have new DC-DC converter approaches to smoothly onboard and operate PV and wind energy production with DC grids.

Brief description not available

Brief description not available

Brief description not available

Brief description not available

Brief description not available

Brief description not available

Brief description not available

Brief description not available

The inventors have discovered a new way to generate ultrafast back-gating, by leveraging the surface band bending inherent to many semiconductor materials. This new architecture consists of a standard bulk semiconductor material and a layered material on the surface. Optical pulses generate picosecond time-varying electric fields on the surface material. The inventors have successfully applied this method to a quantum well Rashba system, as this is considered today one of the most promising candidates for spin-based devices, such as the Datta Das spin-transistor. The technology can induce an ultrafast gate and drive time-dependent Rashba and quantum well dynamics never observed before, with switching faster than 10GHz. This approach minimizes lithography and will enable light-driven electronic and spintronics devices such as transistors, spin-transistors, and photo-controlled Rashba circuitry. This method can be applied with minimal effort to any two-dimensional material, for both exfoliated and molecular beam epitaxy grown samples. Electric field gating is one of the most fundamental tuning knobs for all modern solid-state technology, and is the foundation for many solid-state devices such as transistors. Current methods for in-situ back-gated devices are difficult to fabricate, introduce unwanted contaminants, and are unsuited for picosecond time-resolved electric field studies.  

Prof. Ming Lee Tang and her colleagues from the University of California, Riverside have developed a promising new material for photonic devices utilizing hybrid materials composed of inorganic semiconductor nanocrystals and organic acene molecules. The material allows for photon upconversion, a promising wavelength shifting technology for photon management. This multi-photon process has potential applications in biological imaging, photocatalysis and photovoltaics. Regarding solar energy systems, the conversion of low energy near-infrared (NIR) photons to higher energy photons is particularly appealing, considering NIR radiation comprises 53% of the solar spectrum. Current solar panels are greatly limited in efficiency due to this. Reshaping the solar spectrum to match the optical properties of common semiconductors will allow the efficient use of all incident light. This holds the potential to solve the largest issue that current solar panel systems face.

Brief description not available