Quantum dot

Quantum dots (QD) are semiconductor devices that tightly confine electrons or holes in all three spatial dimensions. They can be made via several possible routes including colloidal synthesis, plasma synthesis, or mechanical fabrication. The term “quantum dot” was coined by Mark Reed in 1988; however, they were first discovered in a glass matrix by Alexey Ekimov in 1981 and in colloidal solutions by Louis E. Brus in 1985. The electronic properties of the quantum dots fall between those of bulk semiconductors and those of discrete molecules of comparable size, and optoelectronic properties such as band gap, can be tuned as a function of particle size and shape for a given composition. For example, the photoluminescence of a QD can be manipulated to specific wavelengths by controlling particle diameter. Larger QDs (radius of 5-6 nm, for example) emit longer wavelengths resulting in emission colors such as orange or red. Smaller QDs (radius of 2-3 nm, for example) emit shorter wavelengths resulting in colors like blue and green, although the specific colors and sizes vary depending on the exact composition of the QD.