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Dye sensitized solar cells


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Dye sensitized solar cells are combination of inorganic semiconductor and organic dyes.

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Dye sensitized solar cells

  1. 1. Dye Sensitized Solar Cells Organic optoelectronics| Ashish Singh| B10007
  2. 2. Introduction  Low cost solar cells  Invented by Brian o’ Regan and Michael Gratzel at UC Berkley  Conversion efficiency lower then other thin film cells.  Price/performance ratio is better.  Manufactured through Roll printing technique.
  3. 3. Dye Sensitized Solar cells
  4. 4. Components The DSSC device consists of 4 components: Semiconducting electrode  n-type TiO2 and p-type NiO Dye-sensitizer  Light harvesting and electronic transition Redox mediator  I- / I3- or CoII / CoIII complexes Counter electrode  Carbon or Pt
  5. 5. Working Principle  Dye Sensitizers absorb the Sunlight, which results in electron injection into conduction band of Oxide (charge separation takes place at interface of oxide and dye).  The dye molecules are quite small (nanometer sized), so in order to capture a reasonable amount of the incoming light the layer of dye molecules needs to be made fairly thick, much thicker than the molecules themselves.
  6. 6. Working Principle  Original state of Dye is subsequently restored by electron donation from the electrolyte(Redox iodide/Triodide).  Iodide is regenerated in turn by the reduction of triiodide at the counter electrode the circuit being completed via electron migration through the external load.  I3  3I - 2e - 3I - I3 2e - | Redox regeneration at the counter-electrode (oxidation). |Dye regeneration reaction (reduction).
  7. 7. Working Principle  The voltage generated under illumination corresponds to the difference between the Fermi level of the electron in the solid and the redox potential of the electrolyte.  Overall the device generates electric power from light without suffering any permanent chemical transformation
  8. 8. Energy Level Diagram
  9. 9. TiO2  Low cost  Widely available  Biocompatible material  Non toxic
  10. 10. Dye Sensitizers  Absorb all light below a threshold wavelength of about 920 nm.  Contain attachment such as Carboxylate or Phosphonate group for better attachment with semiconductor oxide.  Quantum yield of unity for injection of electrons in Semiconductor oxide.
  11. 11. Dye Sensitizers  Energy level of the excited state should be well matched to the lower bound of the conduction band of the oxide to minimize energetic losses during the electron transfer reaction.  Stable enough to sustain about 10^8 turnover cycles corresponding to about 20 years of exposure to natural light.
  12. 12. Dye-sensitizers
  13. 13. Efficiency  Electrical power generated =Isc * Voc  Voc ~ 0.7 (greater then normal Silicon cells)  Isc for DSSC ~ 20 mA/cm2 an Silcon cells ~ 35 mA/cm2 Peak conversion Efficiency achieved ~ 11 % Max . Peak conversion Efficiency ~ 15 %
  14. 14. Disadvantages  Liquid electrolytes are corrosive in nature (iodide/Triiodide couple).  Temperature instability of Liquid electrolytes (freeze in low temp. and expansion high temp.)  Health hazard of Electrolytes.
  15. 15. Solid state Dye Sensitized Solar cells  Solid hole conductor instead of liquid Electrolytes.  The charge transfer material currently used is a spirobifluorene
  16. 16. Solid State Dye Sensitized Cells  Hole transfer occurs directly from the oxidized dye to the HOMO level of the hole conductor, which then transports the charge to the (typically silver) counter electrode.  Dye regeneration occurs over a period of tens to hundreds of picoseconds — several orders of magnitude faster than regeneration with the I - /I 3 couple.
  17. 17. Conclusion  DSSCs show the most promising future due to their independence, environmentally friendly, low maintenance, and low cost .  A solar energy system can be installed in any location without a connection to a power grid.  The initial investment is expensive. Once the use of electricity reaches to a certain point, the solar energy is free.  After installation, there is no recurring cost and it can be used for a long time.
  18. 18. Bibliography  Grätzel, M. (2003). Dye-sensitized solar cells. Journal of Photochemistry and Photobiology , 145-153.  hardin, B. e., snaith, h. J., & McGehee, M. D. (2012). the renaissance of dye-sensitized solar cells. The nature photonics , 162-171.  Nagata, T., & Murakami, H. (2009). Development of Dye-sensitized Solar Cells. ULVAC Technical Journal , 70E.  Dye Sensitized solar cells. (n.d.). Retrieved from
  19. 19. Thank You !!