Presentation about 'Quantum Dot solar cell.pptx

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1) introduction
2) construction
3) working
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1. QUANTUM DOT SOLAR CELL Presented By :- Abhisek Sahoo +3 3 rd YEAR(6 th sem ) R05021PHY005

2. INDEX Introduction History Quantum dots Solar Cells Need for Quantum dots in Solar Cells Quantum dots in Solar Cells References

3. Introduction A Quantum Dot Solar Cell(QDSC) is a solar cell design that uses quantum dots as the light absorbing photovoltaic material. It replace bulk materials such as silicon, copper indium gallium selenide(CIGS). Quantum dots are special class of semiconductors and are nano crystals. The energy band increases with decrease in size of quantum dots. The adjustable band gap of quantum dots allows the construction of nano structure solar cell, that is able to absorbs maximum amount of solar spectrum.

4. HISTORY The idea was noted by Burnham and Duggan in 1990. Later, quantum dot solar cells emerged in 2010 as the newest technology on an NREL(National Renewable Energy Laboratory)chart that tracks research efforts to convert sunlight to electricity with increasing efficiency. Quantum dot Solar cell

5. QUANTUM DOT Quantum dots are special type of semiconductor and very small in size. Size from (2-10) nanometers in diameters. Zero(0) Degree of Freedom They can emit light or absorb it, depending on their size and composition. The energy band gap increases with decrease in size of quantum dots. The adjustable band gap of quantum dots allows the construction of nano structure solar cell , that is able to absorb maximum amount of solar spectrum. Quantum dots are some time called “artificial atoms”.

6. SOLAR CELL A Solar cell is like a tiny power generator that takes sunlight and turns it into electricity. It’s made of special materials that create an electric current when light shines on them. These cells are often grouped together to form solar panels , which can be used to power things like home, calculators , or even spacecraft . It’s a clean and renewable way to generate power without polluting the environment .

7. Need for Quantum dots in Solar Cells Reduction in cost :- - of each kilowatt of electricity produced - of raw materials - of processes used to convert the raw materials into functional cells Inefficiencies in conventional single junction solar cells - inability to absorb all of the solar energy - inability to convert all of the photon energy that is absorbed to free electrons and holes Traditional semiconductor materials are crystalline or rigid

8. QUANTUM DOT IN SOLAR CELL Quantum dot solar cells are a type of solar cell that use tiny particles called quantum dots to absorb sunlight and convert it into electricity. It is more efficient than traditional solar cell and it’s utilization efficiency of sunlight about 66%. They still being developed , but they could be a big deal in the future of solar energy.

9. Properties High efficiency : QDSCs can achieve high conversation efficiencies due to their ability to absorb a broad range of the solar spectrum compared to conventional solar cells. Size tunability : The optical and electronic properties of QDs can be tuned by adjusting their size , making them highly versatile for use in various applications . Low cost : QDSCs are relatively low-cost to produce compared to other types of solar cells .

10. construction

11. WORKING Step1:- Excitation Upon absorption of a photon , a quantum dot is excited from the ground state(QD) to a higher energy state(QD*). QD + h v QD* QD and QD* are the quantum dot in its ground state and excited state respectively. Step 2 :- Formation of Electron – Hole Pair The absorption process results in the creation of electron-hole pair in the form of exciton. QD* QD(e - *+h + *) Dissociation of the exciton occurs if the thermal energy exceeds its binding energy.

12. WORKING Step 3:- Injection Process The excited electron is then injected in the conduction band of the wide band gap semi conductor TiO2 thin film This process will cause the oxidation of the photo sensitizer QD(h + *). QD(e - *+h + *) + TiO2 TiO2(e - *) + QD(h + *) Step 4:- Energy Generation The injected electron is transported between the TiO2 nano particles , and then gets extracted to a load where the work done is delivered as electrical energy. TiO2(e - *) + CE TiO2 + CE(e - *) + Electrical energy

13. WORKING

14. WORKING

15. APPLICATIONS Used in power portable electronic devices Used in building-integrated photovoltaic cells Used in space applications

16. REFERENCES http://www.evidenttech.com/ http://en.Wikipedia.org/wiki/Solar_cell http://en.Wikipedia.org/wiki/Quantum_dot http://softpedia.com/ http://www.sciencedaily.com/articles/ http://www.i-sis.org.uk/index.php/ White Paper:- Brad Gussin , John Romankiewicz Peter Green L.H. Slooff ,R. Kinderman , A. R. Burgers , J.A.M. van Roosmalen UC-Davis Physics , CM Journal Club