what are quantum dots and its applications

Quantum dots are very small semiconductor particles only several nano meters in size. So small that their optical and electrical properties differ room those of larger particles. They are a central theme in nano technology. Most of all types of quantum dot will emit light of specific frequencies if electricity or light is applied to them. In addition frequencies can be precisely tuned by changing the dots size and shape and material giving rise to many applications.

Quantum dots

Quantum dots exhibit properties that are intermediate between those bulk semiconductors and those of discrete molecules. Their opted electronic properties change as a function of both size & shape larger qd’s emit longer wavelength. Which resulting in emission of colors such as orange or red. Smaller qd’s 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. Because of their highly tunable properties QD’s are of wide interest. Potential applications include transistors, solar cells, led’s, diode lasers and second harmonic generation quantum computing and medical imaging.

quantum dots

Additionally their small size allows for QD’s to be suspended in solution which leads to possible uses in the inkjet printing and spin coating. These processing techniques  is less expensive and consumes less time which is  a  method of semiconductor fabrication.

How does Quantum dots work

 When energy is applied to an atom electrons are energized and move to a higher level. When the electron returns to its lower and stable state, this additional energy is emitted as light corresponding to a particular frequency.

Quantum dot work in much the same way but a quantum dot crystal acts as one very large atom. Since Large quantum dots produce light with a long wavelength and small quantum dots produce light with small wavelength. In terms of color in the visible spectrum this means large quantum dots produces blue light sizes in the spectrum.

quantum dots

By combining a range quantum dot sizes in the same sample the entire light spectrum can be simultaneous and as white light. Quantum dots can be manufactured by a number of processes from colloidal synthesis to chemical vapor deposition. The cheapest and simplest method in bench top colloidal synthesis electrochemical techniques and cvd can be used to create ordered arrays of quantum dots on a substrate material.

Advantages

  • These have become a hot technology in the display devices like monitors.
  • This QD technology can improve liquid crystal display dramatically in terms of color gamut.
  • These qd’s help in giving crystal HD display.

Disadvantages

  • Quantum dots can have surface defects.
  • Although qd’s are in the nano-meter range, bi-conjunction with different molecules will increase the size dots making delivery into cells is difficult.
  • The poisonous nature of quantum dots to cells is a major issue.
  • Quantum dot metabolism and degradation inside the body is still widely unknown and several studies have shown.

Applications

  • Most of all high usage in medical field.
  • A current applied directly to the quantum dots between these layers will cause them fluorescence. Probably it will be an extremely high efficiency light source.
  • Almost the energy emitted from quantum dots as light is close to 100 % of the energy put into the system.

 

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