Quantum Dots are Illuminated Under Stress

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An international team of researchers who participated in the teachers Fernando Rajadell, Juan I. Climente and Josep Planelles the Department of Physical Chemistry at the Universitat Jaume I (UJI) has designed a new technique to manipulate the fluorescence (light emission) quantum dots that opens the door to the design of new devices with properties beyond the traditional method of confinement cuántico. Los semiconductor nanocrystals, or quantum dots are tiny particles of nanometer size with the ability to absorb light and re-emit it with well defined colors. Thanks to a low manufacturing cost, its long-term stability and a wide palette of colors, have become an important base of visual technology, by improving the picture quality of televisions, tablets and mobile phones. They are also emerging interesting applications of quantum dots in the fields of green energy, optical sensing, and bio-imaging.

The prospects are even more attractive after a publication entitled "Band structure engineering via anisotropic piezoelectric fields in strained CdSe / CdS nanocrystals" ("Engineering band structure using piezoelectric fields in anisotropic quantum dots of CdSe / CdS under stress" published in the journal Nature Communications last July. An international team of scientists of the Italian Institute of Technology (Italy), the University Jaume I (Spain), the IBM research laboratory in Zurich (Switzerland) and the University Milano-Bicocca (Italy) demonstrated a radically new approach to manipulate the light emission of quantum dots.

The traditional principle of operation of the quantum dots is based on the so-called quantum confinement effect, whereby the particle size determines the color of the emitted light. The new strategy is based on a completely different physical mechanism; an electric field with voltage induced within the quantum dots. This is created by growing a thick frame around the points. Thus, researchers could compress the inner core, creating intense internal electric field. This field becomes the dominant factor in determining the emission properties.

The result is a new generation of quantum dots whose properties beyond those generated only by quantum confinement. This not only expands the scope of the materials known CdSe / CdS, but also other materials. "Our findings add an important new degree of freedom to the development of technological devices based on quantum dots," say the researchers. "For example, the time between the absorption and emission of light time can be extended to more than 100 times higher compared to conventional quantum dots, which opens the way to new devices for optical and intelligent pixel memories. The new material could also result in highly optical sensors sensitive to electric fields in the nanoscale environment. "