AuthorBY- SUPRAJA G.S Before diving deep let’s see some basics, what actually a normal solar cell is ?, Solar cells work under the effect of the Photovoltaic effect which actually is the generation of voltage and electric current in a material upon exposure to light. It is a physical and chemical phenomenon. Majorly silicon is used in the production of solar cells. Today let’s see how Carbon Nanotubes and Quantum dots can be used to meet our objective of reducing the production cost while increasing efficiency. Let’s start with the problems that are faced in primitive solar cells and how Nanotechnology aids them. QUANTUM DOTS: Primitive Solar cells are not capable of converting the entire received light to proposed energy since few particles of light can evolve into the air. Added to it, light rays occur in multi-colors or spectrum as we know and the cells harness blue night and function at a slow rate in conversion of reddish light & Infrared. Silicon has more bandgap which requires more energy to pull out the electrons from the excitons. Semiconductor quantum dots are used as the absorbing photovoltaic material which adjusts the bandgap thereby absorbing the longer wave light and increasing the output. When the quantum dots of 1 nm diameter was used it was observed that 67 % of blue light and 60 % of red Quantum dots also have a high possibility of multiple exciton generation. in which one-photon absorption will emit 2 + excitons that mean more than two electron-hole pairs is obtained, whereas only one electron-hole pair is generated in normal solar cells. With all these put together, quantum dots has proved to improve the efficiency of the solar cell up to 55%. CARBON NANOTUBES: Now lets see how Carbon nanotubes(CNT) are useful. In primitive solar cells, The electrons that are freed by the interaction of the sunlight within the semiconductor material creates an electron flow as the free electrons move together around an external circuit. Usually electrons follow through a complex path to reach electrodes, but easier ballistic transport of electrons on solar cell surface was achieved successfully by using the CNT’s along the axis, with high current density and reduction in loss.
Another major problem is heat generated during the day time, which decreases the efficiency. But with the help of carbon nano tubes we can harness them as well, heat specifically infrared heat from the sun, solar cells that are designed with array of cavities patterned into a film of aligned carbon nanotubes as shown in the figure, absorbs and channels the heat into a form that solar cells can use and the convert to electricity. All these put-together carbon nanotubes have proved to improve the efficiency of the solar cell upto 80%. Advantages : ➢ Nanotechnology with the utilization of solar cells would help to preserve the environment. ➢ The inexpensive photovoltaic cells which are enough to cover with the roofing materials. This will decrease the fossil fuels and helps to reduce pollution. ➢ The nanotechnology improves the standard of living up to billions of people. To generate the power the car coating with photovoltaic solar cells and solar cell windows were used. Scientists are finding a way to incorporate both Quantum dots and carbon tube nanotubes in a much more efficient way. To produce solar cells with much more efficiency. With this, I conclude Nanotechnology infused solar cells is a boon to human society and the best aid to the future energy source for mankind.
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