As-8.docx

Solar Photovoltaics: Energy, Technologies and Materials Assignment-08 1. In CIGS solar cells, p-type character of Cu(InGa)Se2 is attributed to:  Copper interstitials  Selenium vacancies  Selenium-Copper complex  Copper vacancies 2. In CIGS solar cells, increase in In/Ga ratio leads to?  Lowering of bandgap  Increase in bandgap  Change in crystal structure  Increase in short circuit current 3. Soda lime glass is used as a substrate for fabrication of CIGS solar cells because:  Na reduces bulk defect density  Na helps in surface passivation  Na improves texture of CIGS films  Na reduces series resistance 4. In multijunction solar cells with light entering from top, what should be the design strategy?  Low band gap material is the top most layer.  Material with highest absorption coefficient is on top.  Low band gap material is the bottom most layer.  High band gap material is the top most layer. 5. Exciton dissociation in single junction organic solar cells requires:  Presence of an electric field in the device  Presence of interfaces where exciton can dissociate  Large thickness of photo-absorbing layers  Cathode and anode of same work function 6.

Low efficiency of organic solar cells is generally due to:  Lower quantum efficiency  Relatively high bandgap of polymeric materials  Poor absorption coefficients  Inappropriate electrodes

7. Organic polymers exhibit semiconducting behavior due to:  presence of benzene ring  delocalization of sigma electrons  delocalization pi electrons  doping by elements such as I or S 8. Bulk Heterojunction organic solar cells are superior to bi layer organic solar due to :  Improved dissociation of excitons into free carriers  Relatively thin absorber layer  Better optical absorption  Improved contacts 9. For better photovoltaic performance, the photosensitizer used in DSSC solar cells should have:  Low band gap  High band gap  High ionic conductivity  High electronic conductivity 10. Assuming that light enters from top, the thickness of the bottom layer in tandem solar cells is related to:  External quantum efficiency in higher wavelength region  External quantum efficiency in lower wavelength region  Absorption in higher wavelength region  Absorption in lower wavelength region 11.    

In a perovskite solar cell, the perovskite layer is used as a: N-type layer P-type layer Intrinsic layer Light absorbing layer

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In a conventional dye sensitized solar cell, which of the following do/does not happen? Absorption of photons by the sensitizer Migration of electrons through TiO2 Migration of holes through the electrolyte Absorption of hole by dye molecules during regeneration

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The electrolyte in a dye sensitized solar cell must have: High electronic conductivity High ionic conductivity High optical absorption coefficient Good stability

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Perovskite solar cells can be fabricated with which of the following structures? P-I-N structure N-I-P structure P-N structure Bulk heterojunction

15. What is the correct sequence of conversion of light into current in organic solar cells?

 Absorption of light exciton formation exciton dissociationcharge collection  Absorption of light exciton formation exciton dissociationfree charge carrier diffusionexciton collection

 Absorption of light exciton formation exciton diffusionexciton dissociationfree charge carrier transportcharge collection

 Absorption of light exciton formation exciton diffusionexciton dissociationcarrier diffusioncarrier transportcharge collection