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Submission + - Practical solid state lighting gets closer (rsc.org) 6

slashdotlurker writes: "During all the talk about the new energy revolution, and need for moving off our oil habit, one aspect of this problems tends to get forgotten — conservation. According to Department of Energy statistics, the US uses almost 22% of all the electricity produced on lighting on homes, commercial buildings, factories, etc. The basic cause of this is the widespread use of the incandescent bulb. Though their use has declined, the compact fluorescent lamps (CFL) they are replaced with, only increase the efficiency by about 5 times, while potentially causing serious health hazards with mercury used in CFLs.

Light emitting diodes have long been presented as an alternative. They are almost 10 times more efficient than incandescent bulbs, and have much longer lifetimes than CFLs. The best part is — they do not use mercury. The problem is cost. Since silicon cannot be used as an LED material, and gallium used in gallium arsenide and gallium nitride is a rare element, it has been impractical to use these inorganic materials in commercial lighting. White organic light emitting diodes (WOLEDs) have been presented as cheaper alternatives, but the method of depositing the materials is often expensive, and wastes a lot of material.

In a paper just published in Soft Matter (subscription required), a team of US scientists partnering with a Japanese company may have finally broken this barrier. They combined some hybrid organic and inorganic materials to create a hybrid macromolecule, mixed it with a polymer, and then printed it to create extremely bright light emitting diodes. They claim a value of 10,000 candelas per square meter. For comparison, a computer monitor puts out about 300.

This is one of the first times that such high brightness printed light emitting diodes have been reported, using a process that wastes almost no material at all. The kicker is that since this was printed, this can be done over very large areas (think walls).

Is practical, cheap, efficient solid state lighting finally here ? I am already imagining walls of bright light emitting material, with no ugly electrical fixtures sticking out at all."

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Practical solid state lighting gets closer

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  • This could be a huge improvement for pocket projectors, especially if it runs cooler than conventional LEDs. Also since it seems to be spread over an area rather than a point source, it would possibly allow the same device to be used directly as a screen by removing the optics that collimate the projection. Of course the image would have to be flipped and/or rotated, but that is not exactly a big hurdle.


    • I had not thought of that. Since they are printing this stuff, they could even deposit it on a flexible display, which means you can stash it away when you are done.

      Kind of like a roll away projector screen that is actually an active display, which is kind of cool. They can then flip the image in the logic board, which is pretty easy as you say.

      They did not quote any temperature ranges, but it seems that their macromolecule has a transition temperature of 54C. From what I remember of my undergrad, I
    • Is there a good reference for the lifetime issue you asked about ? How do these things actually degrade (other than just burning out) ?
  • "Douglas-Martin shadowless skyfoam"

  • I think that taking the time to write summaries and submitting stories is a waste of time. None of mine ever get accepted anyways. Its best to mooch off other people's efforts.

Never keep up with the Joneses. Drag them down to your level. -- Quentin Crisp