Quantum Dots: What Are Quantum Dots, Their Uses And Functionalities
Nanoparticles are materials measured by a nano scale. These are used in nanotechnology by researchers to discover the uses of these elements in the nanoscale form. Quantum dots, with diameters ranging from 2 – 10 nanometers i.e. 10 – 50 atoms, are nanoparticles. This means that diameters of quantum dots are 1/1000th the width of the human hair. These tiny particles or nanostructures are semiconductor materials and exhibit quantum mechanical properties.
Alexey Ekimov first discovered quantum dots, named as such by Mark Reed, in a glass matrix in 1981. Later in 1985 Louis E Brus discovered these dots in colloidal solutions. The quantized energy levels of the dots relate them more to atoms than to molecules and hence, they are also known as “artificial atoms.”
Their unique electronic properties, ranging between the properties of bulk semiconductors and those of discrete molecules, are related to size and shape. The band gap (energy range where no electron states exist) is inversely related to its size, and this is what determines the range of frequency in emitted light. After being illuminated by light, these nanoparticles glow a particular colour depending on the size of the nanoparticle.
Why should you use Quantum Dots?
Due to the unusually high surface to volume ratios, one could buy quantum dots because it can exhibit optical and quantum electrical properties which find use in the electronic industries. Its unique quantum size also finds numerous applications.
Due to their high extinction coefficient, one can buy quantum dots because it finds use in optical applications. These nanocrystals can produce characteristic colours depending on their size resulting in fluorescence. As their size increases, these dots have a greater spectrum shift towards the red colour. So, as the quantum dot decreases in size, the frequency of emitted light increases and the colour keeps changing from red to blue which finds application in the fluorescent dye. The unique optical property of quantum dots is being used in LCD TVs also to produce more accurate and brighter colours.
As the size of quantum dots can be tuned when they are being made, this can be made use of in controlling the conductive properties of these dots during the time they are made.
In the biological analysis, many traditional organic dyes are being used which need to be flexible with the advancement of technology but are not so. Owing to their optical properties, quantum dots are 20 times brighter than organic dyes. Also, quantum dots have been found to be 100 times more stable than organic dyes. Quantum dots are also brighter and degrade little over time compared to the traditional organic dyes that are used in biomedical applications.
Medicinal and other uses of dots of quantum nature
Owing to their size, one could buy quantum dots because it can go anywhere in the body. This property finds use in different biomedical purposes like biosensors and fluorescent biomedical imaging.
Today’s photovoltaic cells may be replaced by quantum dots that may increase efficiency and decrease cost. In solar cells, one electron is generated by one photon of light while in quantum dots one photon of light can generate two electrons ultimately leading to the efficient production of electric power.
Many methods have been recommended in the use of quantum dots to improve the design of light emitting diodes LEDs as more accurate colours are visible in the light emitted by quantum dots. Some methods that have been proposed are “Quantum Dot White Light Emitting Diode” (QD-WLED) and Quantum Dot Light Emitting Diode" (QD-LED) displays.
In the conversion of water into hydrogen as a passage to solar fuel by the method of using light, quantum dots are used as photo catalysts.
In solid-state quantum computation, quantum dot technology is used where the flow of electrons through quantum dot is controlled by applying small voltages to the leads. This helps in the precise measurement of spins and also to find other properties.
Fabrication of quantum dot photo detectors is done either from conventional single crystalline semiconductors or from solution processing. These colloidal QDPs have latent possibilities of being used in a machine vision, surveillance, spectroscopy and industrial inspection.
The density of states of these quantum dots is sharper due to the fact that they are zero-dimensional. This gives them greater optical and transport properties leading them to be researched for application in amplifiers, biological sensors and diode lasers.
A new generation of quantum dots has extensive possibilities in the study of intracellular processes like high resolution cellular imaging, diagnostics and tumor targeting.