A quantum dot is a particle having an approximate size of one nanometer which has the display properties of a semiconductor. A semiconductor is a solid material that possesses some amount of electrical conductivity. Silicon is one of the most popular materials used in creating a quantum dot.
The size of the quantum dot, one-billionth of a meter, can cause it to exhibit unusual properties that are not present in larger samples of a semiconductor material. These properties could have some benefits to humans including, but not limited to, energy and light production. Unlike some forms of nanotechnology, the quantum dot is not theoretical. It has been created in a real-world setting.
The key to the quantum dot is in the electrons. Electrons occupy one of two bands in a material’s crystal. By providing the proper stimuli, an electron, or perhaps more than one, can be encouraged to move from one band to the other. As it moves from one band to the other, it creates a hole, which is positively charged. Together, the hole and the electron are referred to as an exciton.
The electron and the hole in the exciton normally keep their distance from each other. This is called the Exciton Bohr Radius. However, if the crystal is reduced in size, it crowds this gap. Once that happens, it changes the crystal’s ability to absorb and emit energy. At this point, the quantum dot is created. Different colors can be obtained by reducing or increasing the size of the quantum dot.
The quantum dot has a number of different applications. Multiple quantum dots can be used as light emitting diodes in sign displays, cell staining for life science observation, even inks that can aid in spotting counterfeits. Another security application that could soon be realized is luminescent dust, which could be used to track trespassers in restricted areas.
Much like fiber optics, quantum dots may also be used to transmit data. Some estimates suggest that data transfer using quantum dots could be a million-fold increase over standard Ethernet connections.
While these are some of the cutting edge applications, there are also more mundane ones as well. Quantum dots could be used as a light source in buildings, or even an illumination for computer screens.