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Nanorods Emit and Detect Light, Could Lead To Displays That Communicate Via Li-Fi (ieee.org) 33

schwit1 quotes a report from IEEE Spectrum: Ever since 2015 Consumer Electronics Show, quantum dots have been in a market struggle to displace light-emitting diodes (LEDs) as a backlight source for liquid crystal displays (LCDs). Now an advance by a team of researchers from the University of Illinois at Urbana-Champaign, the Electronics and Telecommunications Research Institute in South Korea and Dow Chemical may turn the display market on its head by eliminating the need for backlights in LCD devices. They have produced a LED pixel out of nanorods capable of both emitting and detecting light. In research described in the journal Science, the international team of researchers mixed three types of semiconductors to produce engineered nanorods. "The nanorods contain three different semiconductor materials," explains Shim. "The first semiconductor, which is attached at the tips of the nanorod, is the quantum dot that emits and absorbs visible light." The other two semiconductors are the main body of the rod and the shell around the quantum dot. These components facilitate and control the flow of electrons (negative charges) and holes (positive charges) to and from the quantum dot. The semiconductor materials in the rod and the shell each have a band gap in which no electron states can exist as well as band alignment. With these two semiconductors in contact with the quantum dot, the nanorods are extremely efficient at both emitting and detecting light.
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Nanorods Emit and Detect Light, Could Lead To Displays That Communicate Via Li-Fi

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  • by sheramil ( 921315 ) on Saturday February 11, 2017 @02:07AM (#53844901)
    Maybe they could manufacture billions of them and then arrange them so that they set each other off in patterns and then make an optical model of the human brain.

    No amazing philosophical observations, but it'd make one hell of a light show.

  • Whatever you want to do that involves light, i guess, not just Li-Fi. Why so short-sighted?
  • When I woke up this morning I thought, "you know what would be great? If my screen could get hacked and be recording me at the same time." Slashdot never fails to deliver! ;)

  • Obviously you use it to make a display which is also a camera. Apple has two patents on telescreens; one with a camera hidden behind the display and peeking out between multiple pixels, and one with the receptor elements interspersed throughout the display and lensed in groups to different focal lengths to permit multiple depth of field. Presumably you would do the same as the latter with this technology.

  • TFA misses point ... (Score:5, Interesting)

    by jdagius ( 589920 ) on Saturday February 11, 2017 @06:54AM (#53845373)

    ... namely that these nanorods are incredibly small (5 nanometers), such that they can be 'liquefied' and used as "semiconductor paint". So it's primarily a breakthrough in 'scaling down', not multitasking. Conventional LED's have always had the capability to detect light. (Ever hear of 'photo-diodes'?). But exploiting this dual-functionality has always been inefficient, due to the relatively large size of individual LED's (on the order of millimeters).

    As stated in TFA:
    "Shim concedes that is possible to use a LED light bulb as a light-emitting device or as a light-detecting device. Even more, for thin film inorganic semiconductors this is relatively easy thing to do, and, in fact, sort of similar to what the researchers have done here at the individual nanorod level. But because the researchers have made the LED pixel from this colloidal nanorod, it can be processed in solution and in turn be used to make large arrays of LEDs."

     

    • ... namely that these nanorods are incredibly small (5 nanometers), such that they can be 'liquefied' and used as "semiconductor paint". So it's primarily a breakthrough in 'scaling down', not multitasking. Conventional LED's have always had the capability to detect light. (Ever hear of 'photo-diodes'?). But exploiting this dual-functionality has always been inefficient, due to the relatively large size of individual LED's (on the order of millimeters).

      It IS a breakthrough in multitasking - or at least it could be. Conventional LED's can detect light, but they are too big for making arrays sufficiently dense for any reasonable resolution. The techniques described in TFA may result in large screens which are also basically high-res image sensors. Also, with a speed "about three orders of magnitude faster than a typical video refresh rate", (as stated in TFA), the ability to switch back and forth between display mode and 'camera mode' will be limited only b

      • LEDs are the size they are for economic reasons and to get a reasonable amount of light out of a single die. They can be made smaller, or multiple independently addressable LEDs made on one die.
  • by ka9dgx ( 72702 ) on Saturday February 11, 2017 @10:38AM (#53845873) Homepage Journal

    There obviously aren't many hardware hackers watching this thread, but I just wanted you to know that LEDs also function as photodiodes... back in the 1990s I breadboarded an alarm circuit that used a bi-color LED, with the green as an emitter and the red as a detector, to sense a reflector from a few feet away. I'm fairly certain that you could probably do interesting things with this knowledge and an arduino... like make a device that has a lock that has an single LED as it's heartbeat output, and its unlock input, with a matching keychain, for example.

  • Not a particularly scientific thought, but . . . optical sensors that work like biological eyes. Acoustic sensors which work like biological ears. Proprioception, tactile, olfactory and vestibular senses. Robotic mobility. I wonder what a deep learning algorithm might turn into it limited to these inputs and left running for a decade or two?
  • Well, paranoid people were suspicious before that they could watch you through the monitor.

    Now it's coming true!

  • She'll start calling me "nanorod".

    No, you can't ask why.

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