Tag Archives: energy

Room-Temperature NDR Polymer Diodes for Flexible, Low-Power Electronics

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Summary:

Devices that exhibit a phenomenon known as negative differential resistance (NDR) have tremendous potential to deliver the kind of low-power circuitry needed in a variety of electronics applications. To understand NDR, it is instructive to recall Ohm’s Law, V=IR. For a fixed resistance (R), as voltage (V) increases, current (I) increases in a linear fashion. In NDR, there is a voltage range where increasing voltage actually results in a decreasing current. This behavior has many beneficial design properties, one of which is the design of low power memory and logic or even energy scavenging from the environment, eliminating the need for a self-contained battery.

Until now, successful demonstrations of NDR have been limited to rigid, inflexible semiconductor-based devices that are unsuitable for certain applications. Researchers at The Ohio State University have developed a polymer-based device that exhibits NDR and has the flexibility needed for advanced applications such as smartcards and wearable electronics. These devices enjoy very fast operation, which leads to high performance while consuming very little power. Furthermore, these devices can be manufactured in a very cost-effective manner using simple printing techniques.

Potential Applications:

  • Smartcards
  • Energy Scavenging
  • Development of advanced logic and memory circuits on flexible substrates

Advantages:

  • Large and reproducible NDR, at room temperature, in a flexible polymer device!
  • Low cost and simple solution processing
  • Fast operation at low power

Carbon Monoxide (CO) Detector Operating at Room Temperature

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Summary:

Existing CO sensors are usually of either the electrochemical or optical variety. Inexpensive optical sensors, usually battery powered, are limited in their precision and lack displays to determine exact levels of CO concentration. Electrochemical devices offer higher precision and offer a display for CO concentration, but must operate at elevated temperatures and thus must be plugged in to a wall outlet. Researchers at The Ohio State University have developed an electrochemical CO sensor that operates and senses CO at room temperature, thus eliminating the need for a heating device. Therefore, energy demands are far lower when plugged in to a wall outlet, and a battery-powered electrochemical CO sensor can be achieved. This sensor can monitor CO in the ppm range and can be readily fabricated by screen printing techniques with deposition on polymer substrates. Sensors are miniaturizable.

Potential Applications:

  • Home, office, and industrial CO monitoring for occupant safety and fire detection
  • CO sensors can be incorporated into mobile devices, such as cell phones

Advantages:

  • Increased safety and sensor longevity as no heating device is needed
  • For the first time, battery-powered electrochemical CO sensors are possible
  • A portable, battery-powered CO sensor with a display becomes possible
  • Great reduction in energy consumption
  • Low-cost and easy to manufacture

Graphene Composites as the Cathode Material of High-Power Lithium Ion Batteries

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Summary:

Lithium ion batteries, commonly found in today’s mobile devices, are poised to play a major role in serving our future energy needs. While current batteries are suitable for mobile phones and laptops, their energies and power densities are insufficient for more demanding applications such as transportation and mass energy storage. The major limiting factor in lithium ion battery performance is in the cathode material, and various materials have been identified that offer large capacity, low cost, chemical stability, and environmental friendliness. Unfortunately, these materials also suffer from very poor electrical conductivity. Much research has focused on forming composites of these materials with different kinds of carbons, conductive polymers, metals, and oxides in order to alleviate this issue, with little success. Researchers at The Ohio State University have developed composites of these materials with graphene (planar atomic sheets of graphite) that exhibit excellent electrical conductivity while maintaining the beneficial properties noted above. The researchers have developed one type of graphene composite that boosted the electrical conductivity (compared to the material alone) by eight orders of magnitude. Amazingly, in this case graphene only makes up 3.6% of the composite by weight! Other material systems and methods of manufacture have been developed, and continue to be investigated, that could yield even more impressive results.

Potential Applications:

  • High density energy storage for alternative energy sources
  • Transportation (e.g. hybrid and plug-in electric vehicles)
  • Mobile devices (enables much longer life and better performance with a smaller battery)

Advantages:

  • A major breakthrough in the quest for high performance lithium ion batteries with large energy densities
  • Enables an environmentally friendly cathode material that exhibits large capacity, low cost, chemical stability, and high electrical conductivity
  • In one test, adding as little as 3.6% graphene by weight boosted the electrical conductivity of a material by eight orders of magnitude
  • Low carbon content in electrodes due to the use of graphene (3.6% by weight) results in enhanced overall gravimetric and volumetric capacities
  • Exhibits superior rate capability, maintaining ~70% capacity at 20 C

Novel Organic Light Emitting Diode (OLED) Technologies for Lighting and Display Applications

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Summary:

Researchers at The Ohio State University have developed a comprehensive portfolio of Organic Light Emitting Diode (OLED) technologies that include novel materials and device architectures as platforms for functional devices and for device manufacturing. These developments improve material stability over time while improving their performance such that the required voltage can be reduced and improved electroluminescence can be obtained with reduced power consumption. The bilayer device structure improves device quantum efficiency and brightness due to charge confinement and exciplex emission at the emitting polymer interface. Beyond advancements in the materials themselves, novel device architectures have been developed which are independent of the materials used. These advancements may be of significant value in simplifying manufacturing, thereby accelerating the displacement of LCD and plasma display technologies as well as the displacement of traditional incandescent and fluorescent lighting sources. The associated patent portfolio consists of 8 patent families with a total of 11 issued U.S. patents and 39 associated national stage filings (spanning all US cases). A listing of all issued U.S. patents can be found below.

Potential Applications:

  • Conformal, designable, and color-variable interior and exterior lighting for residential and commercial environments
  • Power and weight sensitive lighting and display applications (e.g. aircraft interior lighting, portable display backlighting)
  • Portable lighting devices such as flashlights
  • Light, ultra-thin, flexible displays with rich colors viewable from very wide angles
  • Body-wearable lighting and display applications
  • Nearly endless list of potential applications

Advantages:

  • More energy efficient lighting source compared to incandescent and fluorescent approaches
  • Color quality matches or surpasses conventional approaches in lighting and display applications
  • Estimated useful life is approximately 17-25 times longer than incandescent lighting and nearly twice as long as linear flourescent lighting (which is commonly used in modern LCD displays)
  • Polymeric material is conformal to a wide range of surface topologies and allows for ultra-thin, flexible displays
  • Low cost, materials-independent architectures have the potential to lower manufacturing costs
  • Adjustable color spectrum

Low Temperature Working Carbon Monoxide (CO) Sensor Based on Au/SnO2 Core-Shell Nanoparticles

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Summary:

SnO2-based CO sensors are widely used in domestic and industrial applications and belong to the class of metal-oxide semiconductor (MOS) sensors. This class of sensor is easy to manufacture and miniaturize, and sensitivity and selectivity are both tunable. Also, electrochemical measurements are easily realized, require simple electronics, and integration into electronic devices is straightforward. However, since sufficient oxygen vacancies are needed for conduction, MOS sensors typically operate at elevated temperatures, which requires energy consumption and reduces sensor lifetimes. Researchers at The Ohio State University have developed a MOS CO sensor based on Au/SnO2 core-shell nanoparticles that is operable in the 25 to 150 deg. C range. Sensor response is highly reproducible and recovery is fast in this temperature range, and high sensitivity was exhibited.

Potential Applications:

  • Home, office, and industrial CO monitoring for occupant and fire safety
  • Low temperature and low power requirement makes it compatible with mobile devices

Advantages:

  • A MOS electrochemical CO sensor that operates in the 25 to 150 deg. C range!
  • Increased safety and sensor longevity as no heating device is needed
  • Greatly reduced energy consumption
  • Extremely low cost and easy manufacturing
  • Simple electronics for easy device integration

Self-Supportive Mesoporous Nanowire Arrays For Anodes Of Li-Ion Batteries With High Capacities And Rate Capabilities

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Summary:

This invention provides a complex nano-architectured electrode for rechargeable Li-ion battery with superior energy/power capacity. In particular, this electrode: 1) increases the rate capabilities for high-powered applications; 2) improves the cyclic property in a rapid discharging/charging process and 3) increases the energy capacities. The synthetic method is applicable to large-area fabrication with low costs. No carbon or polymer additives are needed, which will save a mixing step and the method is template free, which is desirable for practical applications.

Potential Applications:

  • Rechargable Li-ion manufacturers
  • Fuel Cell/Electric Car producers

Advantages:

  • Increases the rate capacity for high-power applications
  • Improves the cyclic property in a rapid discharging/charging process
  • Increases the energy capacities
  • No carbon or polymer additives are needed