faculty seminar
DESCRIPTION
Quantum dotsTRANSCRIPT
Quantum DotsAn innovative technology for highly
efficient solar cells
Seminar presented byAmit Coudhary
Asst. Prof.ECE Deptt.
AKGEC Ghaziabad
Introduction to Solar Cells Basic problems with solar cells Multi Layer Solar cell Cost of solar power Semiconductor Quantum Dots Quantum Dots Solar cells Synthesis of Cd-Se Quantum Dots Other applications of Quantum Dots Conclusion
Contents
A solar cell basically is a semiconductor PN junction diode.
Sun light Photons, which have energies comparable to band gap of semiconductor are absorbed by valance band electron and they produce e--h+ pair.
This leads to flow of current in external circuit
Introduction to Solar Cells
Dominant solar cell technology use silicon. Band gap of Si is 1.1eV. If we see Solar Spectrum
Thus Solar to electrical energy conversion efficiency is about 30%
Basic problems with solar cells
Three layer (InGaAs/ GaAs/ InGaP) solar cells, in which three layer have three different Band gaps (1.89/1.42/0.94 eV), can absorb photons from wider range of solar spectrum
Hence their efficiency is higher (48%) as compared to Si solar cells
An infinite layer solar cell will has theoretically maximum efficiency of 86%
Multi Layer Solar cell
Low efficiency of solar cells and their high cost make per unit cost of solar power very high
Cost of solar power
Quantum Dots are semiconductor particles having nanometer dimensions. A QD can have 100 to 100000 atoms
Solution of Schrodinger wave equation for QD suggest that their Band Gap is inversely proportional to their diameter
Examples of QDs are Cd-Se, Zn-O, In-P etc
Semiconductor Quantum Dots
Quantum Dots Solar cells
CdO is added with oleic acid and Octadecene. Then this mixture is heated up to 225o C.
Selenium solution is added to this solution. It produce seed
Cd-Se crystals which grows in size with time
Different samples are taken after each 3 minutes . Thus each sample has Cd-Se QDs with different sizes
Synthesis of Cd-Se Quantum Dots
Other applications of Quantum Dots
By using QDs, efficiency of solar cells can be increased up to 86% (Theoretically maximum efficiency)
This will reduce the per unit cost of solar power
Will also help to make our environment pollution less
Conclusion
Thank You