Nano Technology is that branch of science which studies the behaviour of matter at atomic or molecular scale, which is about 1 to 100 nanometres (1 nm = 1/1000000000 meters) in dimension. The motive is to manipulate the atoms or molecule to design the superior characteristics of the product. The large percentage of the nano particles are found on the surface of the atom than its interiors and because of this reason they exhibit different characteristics than the rest of the atom when sunlight falls on them.
Energy loss in conversion
The normal solar PV cells or panels cannot convert all the incoming sun light into electrical energy as one part of the light is reflected back to the atmosphere and another is lost as a heat, which results in lower efficiency of the solar panel.
Energy at different wavelengths
As you know that the sunlight comprises of 7 colors:
The violet light is having the highest energy levels (lowest wavelength) while the red light has the lowest energy levels (Highest wavelength) in the spectrum of light.
The silicon cells are more efficient in converting higher energy blue light and less efficient in converting low energy red light into the usable energy. Moreover, the part of higher energy is lost as the excited electrons spontaneously combine with the holes and produce heat.
The quantum dots
In the silicon cells the ultraviolet energy is generally absorbed by the cell and is converted into heat but not the electricity.
â€‹By integrating the layer of silicon nano-particles on to the surface of the silicon cell, can boost the overall performance of the cell and this can be done through Quantum dots technology.
The quantum dots are the nano crystals of semiconductor material having finite energy in them. The energy levels and the energy band gap can be modified by changing their size.
It can be said that the desired wavelength of the light can be absorbed by the quantum dots by modifying their size.
This flexibility of tuning energy bang gaps to absorb any wavelength of light by changing their size, without changing the basic material, has made them quite desirable for use in solar cells.
The nano particles of desired size are dispersed on the surface of the silicon cell to enhance the performance of any region (Ultra violet, white light or Infra red) of the spectrum.
This nano crystal film integrated on the silicon cell will absorb more light from the desired region of the spectrum and hence result in enhanced performance in the form of more usable energy.
When sun light hit the quantum dots, they produce more excited electrons which move from valence band to the conduction band. Hence, increases the efficiency of the solar cell
The growth & phases of Nanotechnology
Advantages of using quantum dot nanotechnology
The potential applications of nano technology in solar PV
The research is going on to study the several aspects of solar cells in combination of nano crystals to further increase the efficiency and reduce the manufacturing cost of the solar cells.
â€‹It has the potential to become a revolutionary force for the growth of solar PV market. With this pace of development, the time is not far behind when the people will have nano-technology enhanced solar panels at their roofs.