White light for laptop computers or interior lighting in cars

Things snowballed from there, with scientists making more silicon dots (and, later, germanium dots) that emitted light in lots of bright, pretty colors, especially the highly desirable green and blue ranges. The bigger the dot, the redder the light, and the emitted light becomes shorter and shorter in wavelength — and higher in energy — as the dots shrink in size. This is called "tunability" because you can pretty much tailor the dots to emit whatever frequency of visible light you happen to need for a given application, simply by altering the size of the dots.The most obvious application is using quantum dots as an alternative to the organic dyes used to tag reactive agents in fluorescence-based biosensors. You know, the dyes start to glow when, say, a harmful toxin is present. But the number of colors available using organic dyes is limited, and they tend to degrade rapidly. Quantum dots offer a broader spectrum of colors and show very little degradation over time.
Last year, engineers at Ohio State University "invented a new kind of nano-particle that shines in different colors to tag molecules in biomedical tests." The secret ingredient? quantum dots! This breakthrough — described in the online edition of Nano Letters, in a paper by OSU's Jessica Winter and Gang Ruan — involved stuffing tiny plastic nanoparticles with even tinier quantum dots for use in biomedical tagging applications. It's easier to see biological molecules under a microscope if they fluoresce, and quantum dots glow more brightly than other fluorescent molecules used for this purpose.They also "twinkle", i.e., blink on and off, an effect that is less noticeable if there are many quantum dots congregated together. There are pros and cons to this behavior. Con: it "breaks up the trajectory of a moving particle or tagged molecule" that one is trying to track under the microscope. Pro: when the blinking stops, scientists know they've reached a critical threshold of aggregated quantum dots.
The continuous glowing makes it easier to track tagged molecules with no breaks, and they could also use the color changes to determine when said tagged molecules congregate. The nanopartices would be great for microfluidic devices, and could one day be combined with magnetic particles to enhance medical imaging for, say, cancer detection. In fact, earlier this year, Nature Nanotechnology published the results of a study showing no ill effects over a one-year period in four rhesus monkeys injected with such tiny luminescent crystals.You can also build quantum dot LEDs that emit white light for laptop computers or interior lighting in cars. As for electronics, the possibilities are endless: all-optical switches and logic gates, for instance, with a millionfold increase in speed and lower power requirements, or, further in the future, quantum dots could be used to make teensy transistors for nanoelectronics