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Recent advance in Photorefractive Polymers; SPIE Optics and Photonics; 2011
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A revolutionary cable developed by University of Central Florida researchers can transmit and store electricity at the same time. The cable combines the energy transmission capability of a copper wire, its core, with energy storage made possible by a hybrid battery-supercapacitor, the cable's outer layer. The new technology is applicable to any wired electrical system that benefits from power storage. The cable's flexibility and space-saving nature can revolutionize the design of innumerable electronics--from consumer products like smaller and lighter smartphones, encased with woven, molded energy-storing cable and woven-cable garments able to charge devices, to public sector and military applications for lighter, more fuel-efficient hybrid and all-electric vehicles, heavy machinery, aircraft, and spacecraft.
Technical Details
The energy-storing cable's formation begins with a core conductor wire, on the surface of which nanowhiskers of insulating copper oxide are grown, perpendicular to the wire. The 100-fold increase in surface area enables a higher level of capacitative energy storage. These nanowhiskers are then coated with an alloy of gold and palladium to form the supercapacitor's current collector, followed by an electrochemically active coating of manganese oxide. The first layer is then complete and separated from a second layer of the same composition as the first by a solid electrolyte and porous polymer. Increased surface area from the two layers, each featuring many nanowhiskers, enables high energy storage around the conventional copper coaxial wire for energy transmission.
Researchers at the University of Central Florida have invented a weavable filament that both captures and stores solar energy simultaneously—two capabilities that have only been available in separate devices until now. Thin and ribbon-like, the solid-state Integrated Energy Harvesting and Storage Device (IEHSD) enables manufacturers to provide portable, self-sufficient energy systems in a variety of applications. For example, instead of lugging heavy batteries to power their gear, soldiers on the battlefield could run devices from IEHSD filaments woven into their uniforms. In another example, a jogger could keep a smartphone and health monitors charged by a shirt/clothing made of the smart fabrics (filaments).
Harvesting and storing solar energy typically requires two separate devices: a solar cell, which generates electrical energy, and a battery or supercapacitor, which stores the electrical energy. The size of these devices can limit their portability and use in wearable technology. In comparison, the new invention integrates a solar cell and a supercapacitor into a single, flexible, lightweight filament and widens the scope for even smaller and more powerful electronics. Compared to existing woven circuits with electrically conductive filaments, the new invention has the added capability of storing energy and providing it on-demand—eliminating the need for a bulky, external, energy storage device.
Technical Details
The solid-state IEHSD invention consists of a ribbon-like filament and methods for producing it. Easily woven into textiles and matrices, the filament has two main components: a solar cell that harvests energy and a supercapacitor that stores it. The solar cell can be made of a material such as perovskite, and the supercapacitor can be based on lithium ion technology. A metal material (such as copper) integrates the components via shared electrodes. This enables the device to quickly and efficiently capture, transfer and store energy. In addition, the device can be used to create non-crimp fabric preforms to make an energy-smart structure. Non-crimp fabrics have minimal filament interlacing and extremely long float lengths. As a result, they offer increased axial strength, even penetration of resin in bonded composite structures, and a higher weight fraction of fiber.
Wearable Energy-Smart Ribbons For Synchronous Energy Harvest And Storage, Nature Communications, 2016 Nov 11; Vol. 7, pp. 1331.
Researchers at the University of Central Florida have invented novel materials that enable next-generation supercapacitors to outperform current state-of-the-art energy storage technologies, including lithium thin-film batteries, porous graphene, electrolytic capacitors, and recently developed MXenes and metallic 1T-MoS2. The new hybrid one-dimensional/two-dimensional (1D/2D) core/shell nanowires enable manufacturers to produce flexible supercapacitors with exceptional charge-discharge endurance (for example, 100 percent capacitance retention after 30,000 cycles of charging and discharging).
The invention comprises materials and methods for fabricating arrays of 1D/2D core/shell nanowire supercapacitors with excellent strength and flexibility, high energy density, and superb charge-discharge capabilities. For example, vertically aligned nanowires provide enhanced surface areas for improved adsorption/intercalation of electrolyte ions. Conductive nanowire cores of 1D hexagonal tungsten trioxide (h-WO3) provide efficient carrier transports and capacitive 2D tungsten disulfide (WS2) nanowire shells facilitate ion absorption from electrolytes. The interfaces of the core/shell and nanowire/current collector are chemically self-assembled without any binders or extra materials; thus, ensuring structural integrity. All components are converted from one identical material, enabling one-body structures with remarkable mechanical stability.
High-Performance One-Body Core/Shell Nanowire Supercapacitor Enabled by Conformal Growth of Capacitive 2D WS2 Layers, ACS Nano, October 12, 2016, 10 (12), pp 10726–10735
The University of Central Florida invention describes a new device combining the simplicity of an interdigitated electrode (IDE) with the sophistication of plasmonics for in vitro biosensing applications. The nanoscale geometry of the polyacrylonitrile (PAN) plasmonic layer on a glass substrate is tuned to maximize the targeted interaction of this layer with electrodes and cells which is subsequently measured. Such an interaction could dramatically improve the sensitivity of IDEs enabling the plasmonic interdigitated electrodes (PIDEs) to be a new tool for the electrical and optical analysis of single cells and a network of cells. These devices may be used in applications such as in vitro drug development, single-cell analysis, toxicity testing and organ-on-a-chip models.
Researchers at the University of Central Florida have invented a unique method of creating structures for ultra-thin, highly efficient optoelectronic devices. Current methods (such as depositing PQDs onto a graphene substrate or applying them via spin-coating or dipping) produce structures that offer limited carrier mobility and photoresponsivity. In contrast, the UCF method overcomes these limitations by providing a way to grow PQDs and nanocrystals on any substrate and reduce the separation between them. The resulting structure possesses increased carrier mobility and photoresponsivity.
For example, the inventive group successfully used the method to produce a stable graphene-perovskite quantum dot (G-PQD) superstructure with possibly the highest photoresponsivity and thinnest active layer reported. By effectively combining the versatile optical properties of quantum dots (QDs) with the superior electronic and mechanical properties of graphene, the innovation paves the way for a new class of materials for applications in bio-imaging, solar cells, quantum computing and flexible electronics.
Technical Details
The UCF invention provides techniques for growing QDs and nanocrystals on any substrate via a novel defect-mediated growth mechanism. The method includes placing a precursor on the surface of the material, adding an antisolvent to the precursor, and growing QDs on the surface. Defects can be created by using dry or wet chemistry on one-, two-, or three-dimensional materials such as graphene, carbon nanotubes, or a doped semiconductor. With this method, a structure not only retains the large absorption coefficient and photogeneration efficiency of the QDs, but it also provides the properties of the substrate. The method can be used to replace existing composite structures with a single PQD superstructure. In one example application, the researchers used G-PQD superstructures to make phototransistors. The devices exhibited excellent responsivity of 1.4 × 10^8 AW^-1 and specific detectivity of 4.72 × 10^15 Jones at 430 nm.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
Ultrasensitive and ultrathin phototransistors and photonic synapses using perovskite quantum dots grown from graphene lattice, Science Advances, 12 Feb 2020: Vol. 6, no. 7, eaay5225, DOI: 10.1126/sciadv.aay5225
Researchers at the University of Central Florida have developed a simple, low-cost method of creating electrodes for flexible, robust supercapacitors. The UCF invention resolves the performance and safety issues associated with producing supercapacitors for wearable electronic devices. It also offers a way to build commercially available supercapacitors with high specific capacitance and long cycle life. These capabilities are essential for applications such as microelectronics and hybrid electric vehicles.
Existing fabrication methods require tedious material processing and may use flammable and toxic solvents. Still, others result in electrodes with inferior cycle life or do not meet the bendability requirements of wearable devices. In contrast, the UCF method uses safer aqueous electrolytes to produce vertically aligned graphene-carbon fiber electrodes (VGCFs). Electrodes made with the hybrid material retain 100 percent capacitance after 100,000 electrochemical cycles and 100 percent high-specific capacitance retention after 1,000 bending cycles.
Technical Details
The UCF invention comprises a simple and facile method for fabricating highly efficient supercapacitor electrodes. It includes using pristine graphene sheets that are vertically stacked and electrically connected onto any electrically conducting substrate. The technique results in 3D mesoporous VGCF nanostructures. The graphene displays good adhesion and resists delamination during severe bending and twisting conditions. In an example process, graphene sheets are electrophoretically deposited onto a carbon fiber substrate using nickel ions as the charged elements in the deposition bath. The resulting 3D architecture enables faster and efficient electrolyte-ion diffusion with a specific capacitance of 333.3 F/g. Also, compared to a supercapacitor with metallic current collectors, the supercapacitor is substantially less weight.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
Vertically Aligned Graphene-Carbon Fiber Hybrid Electrodes with Superlong Cycling Stability for Flexible Supercapacitors, Small, 12 September 2019, Vol. 15, DOI: 10.1002/smll.201902606.
Researchers at the University of Central Florida have developed a phototransistor device that can act as an artificial photonic synapse for neuromorphic computing. Ultrathin and highly efficient, the device comprises a superstructure with the fast charge transport capability of graphene (G) and the efficient photogeneration features of perovskite quantum dots (PQDs). The UCF team also devised a unique method for using the device to mimic the synaptic behavior and energy efficiency of the human brain.
Biologically, a synapse acts as a channel of communication between two neurons. One neuron (a presynaptic cell) transmits information to a receiving neuron (a postsynaptic cell). With the UCF invention, the presynaptic signal consists of external stimuli—optical pulses, electrical pulses, or both. The postsynaptic signal is the current obtained across the G-PQD channel.
Technical Details
In one embodiment, the UCF device comprises a substrate with a silicon dioxide layer and a patterned graphene source-drain channel. Grown on the graphene source-drain channel is a perovskite quantum dot layer of methylammonium lead bromide material. The new approach can extend to other 2D materials, including transition metal dichalcogenides and other heterostructures. A method of operating the device as an artificial photonic synapse includes applying a first fixed voltage to a gate of the phototransistor and a second fixed voltage across the graphene source-drain channel. In this example, the presynaptic signal comprises one or more pulses of light or electrical voltage. The postsynaptic signal is a measurement of the current across the graphene source-drain channel. The artificial synapses can strengthen (potentiate) or weaken (depress) based on the appropriate triggers of optical pulses.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
The University of Central Florida invention is a method to grow organic-inorganic halide perovskite quantum dots (PQDs) directly on multi-wall CNTs (MWCNTs) to increase the photosensitivity of optoelectronic synapses. The perovskite quantum dot-multiwall carbon nanotube (PQD-MWCNT) hybrid material acts as an optoelectronic synapse for optoelectronic neuromorphic computing. Brain-inspired (neuromorphic) computing offers lower energy consumption and parallelism (simultaneous processing and memorizing) and provides excellent opportunities in many computational tasks ranging from image recognition to speech processing. To accomplish neuromorphic computing, highly efficient optoelectronic synapses, which can be the building blocks of optoelectronic neuromorphic computers, are necessary.
Researchers at the University of Central Florida have invented a dual-purpose device that can store energy and provide structural support as a body panel of an electric vehicle. The UCF carbon fiber for storing energy (CASE) electrode achieves more than 100,000 charge-discharge cycles with less than 15 percent degradation of capacitance. With this approach, an electric vehicle can achieve 80-100 more miles over its existing range. For example, if a vehicle is currently getting 300 miles per charge, the UCF approach enables it to get 380-400 miles/charge. If the range is 400 miles/charge, it will get 480-500 miles/charge.
Technical Details
When fabricated into an aqueous gel-based, solid-state asymmetric supercapacitor, the CASE fibers store energy via a combined electric double-layer capacitor (EDLC)-redox charge storage mechanism. CASE supercapacitors have high energy density (more than I00 watt-hours per kilogram) and power density (more than 2.5 kilowatts per kilogram).
The devices can be converted into carbon composites using commercial grade epoxies and optimized to meet the mechanical properties of commercial (vehicle) grade carbon composites. With their high tensile strength and impact energy, the composites are moldable as the body panels of electric cars that are safe from fire hazards and toxic material leakage in the event of an accident. They also offer more protection than aluminum or steel, which serve as only structural components in electric vehicle panels.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
The University of Central Florida invention is a new type of organic electrochemical transistor (OECT) called the plasmonic OECT (POECT). The invention leverages the near-field effect of plasmonics to increase the sensitivity of OECTs. Organic electrochemical transistors (OECTs) marked a rapid growth in recent years due to their attractive applications in biosensing, neuromorphic computing and human-machine interface systems. Among all biosensors, OECTs have advantages of high sensitivity, flexibility, biocompatibility, and ease-of-fabrication for commercial applications. The critical and most useful characteristics of the OECT are: