Quantum Dots - An Introduction to New World

      Could you think that you can control the atoms by your own by controlling their motions, vibrations, shutting them on or off and assigning them different colours? Now, the answer will be YES. This can be made possible by QUANTUM DOTS. These are just artificial atoms. Quantum dots (QDs) are man-made nanoscale semiconductor crystal and are zero dimensional, that can transport electrons and has a ability to convert a spectrum of light into different colours. Each dot emits a different colour depending upon its size.

      Just like atoms, QDs also have quantized energy levels. So, as in atoms when electrons gets excited to higher level, they returned back by emitting light of same energy as they absorbed. In this way, they emit colours also. QDs will give out different colours of light depending upon how big they are. The bigger quantum dots produce longest wavelengths (minimum energies) and smaller quantum dots produce shortest wavelengths (maximum energies). That’s why bigger dot is red in colour and smaller is blue and intermediate sized dot is green in colour. This is because bigger QDs have more closely band gap so will require minimum energy to excite electrons and smaller QDs have bigger energy gap so require more energy to excite electrons.

QDs have wide ranging applications covering various areas of catalysis, electronics, imaging, sensors and photonics.

Applications in field of optics

• QDs have interesting optical properties. A thin filter made of QDs can be fitted on LEDs and convert its light into different shades. QDs can be used instead of dyes and pigments. They produce different colours that are brighter and more controllable than dyes.
• QDs have brought revolution in the field of solar cells. QDs produce more electrons (or holes) for each photon that strikes them, potentially boosting efficiency upto 10 percent over conventional semiconductors.
• QDs can also be used in TV screens and computer display. QDs produce light themselves and do not need any backlight, so are energy efficient. They produce high resolution images. QDs LEDs are more brighter than OLEDs.

Quantum computing

Optical computers could use quantum dots in the same way as modern computers use transistors. In quantum computers, bits are stored in atoms, ions and photons all are linked together and are called qubits. These can store multiple values simultaneously and work on different problems together.

Medicine

QDs can be used effectively in cancer treatment. They can easily target one single organ of body liver, kidney, stomach etc. dots are designed such they accumulate in particular part of body and eject anti cancer drug associated to them.