Quantum Dot LEDs: Making custom color LEDs

Let me preface this by saying that this is NOT a cheap experiment by any means. At this time quantum dots are VERY pricey, with typical prices ranging from around $150 to $500 for 10mg. That being said, I used very little per LED. I estimate used about a tenth of a mg or less per LED. So assuming the high end. That is $5/LED and the low end $1.50/LED. Like I said, not cheap but it allows you to literally make ANY color you desire. Also, keep in mind the higher the cost the better quality materials. Don't pay attention to just quantum yield, also keep an eye on accepted variation in emission (this is REALLY important in the green-yellow-orange range) and FWHM. All of that being said, this is something that ANYONE can do. It's as simple as dipping them and evenly coating them in a mixture of QDots and glue.

I am in a unique position in that I research quantum dot synthesis (though for biotech use NOT for electronics use). So I have access to the QDots from failed reactions. All of the LEDs I am making are using failed materials (no I can't sell you any, I'd get fired quicked than you can say QDot :P) which didn't meet our rigorous specs. These are materials which would have been disposed of and are being repurposed just for fun.

I apologize now for the photos. They are grainy because they are all cell-phone pics. My stupid camera up and refused to turn on. So cell-phone pics it is.

Step 1 SCIENCE!

Now on with the article! Have you ever been designing a project and wishing that you had a very specific color of LED? Well thats what this article is going to discuss. But first, some science. If you don't care for the science and theory then skip on to step 3.

Comments

[The Green Gentleman]

This is a really cool instructable. I think your warnings regarding cadmium are dead-on, but as people get kind of blasé about warnings, I thought I would add a link to Itai-Itai Disease article in Wikipedia:

http://en.wikipedia.org/wiki/Itai-itai_disease

Obviously, this is the result of long-term exposure, but even short-term exposure to cadmium dust is nasty, as inhalation is a very efficient means of absorption. So, have fun with this, but listen to PedroDaGr8's warnings, and if you have kids around the house, you might want consider some other way of getting your LEDs looking pretty.

[PedroDaGr8]

Yep, though to be honest. On most of these the cadmium is enapsulated by a zinc sulfide shell. Some tests have shown very minute amounst leaking out but not enough to by cytotoxic. That being said not near enough toxicological research has been done on these to declare them anywhere near harmless. So if you have kids, its better safe than sorry, because typically heavy metal poisoning affects them MUCH more drastically than it does an adult who has stopped growing. Therfore, if you must do this with kids around the house use one of the cadmium-free types of quantum dots. I don't throw warning out just like that. I work with this stuff daily so I know its hazards first hand. Thanks for the link to Itai Itai Disease. I am going to include this in the warnings section as well in an update later today or tomorrow. I have a few things I need to correct; such as saying skip to page 2 instead of skip to page 3 and breaking out the warnings into a separate section.

[PedroDaGr8]

by the way, the commen I don't throw warnings out just like that wasn't directed at you. It was directed at the common reader. Those who know already know that Cd is toxic.

Also, here are some cadmium-free formulations I have found:
CuInS (Copper Indium Sulfide)
InGaP (Indium Gallium Phosphide) - Near IR (~700nm)
InP (Indium Phosphide)
InSb (Indium Antimonide) - not sure on the toxicity of this one.
ZnSe (Zinc Selenide)
CuInP (Copper Indium Phosphide)