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![Why Ruthenium based dyes?
Ruthenium (Ru2+) as a second row transition metal ion has larger Δ◦ and small P
values
Bipy is also a strong field ligand which produces large Δ◦ values
[Ru(bpy)3]
2+ is a d6 low spin complex which is diamagnetic
It possess a singlet ground state and triplet excited state
Radiative transition from triplet excited state to singlet ground state is quantum
mechanically forbidden
It therefore occurs at low efficiency and therefore allows electrons transfer
6/8/2018
8:23 PM
8](https://image.slidesharecdn.com/dyesensitizedsolarcells-180608202343/75/Dye-sensitized-solar-cells-8-2048.jpg)
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Dye sensitized solar cells
- 1. Dye Sensitized SolarCells (DSSC) The Future Of Solar Energy By: Seth Asamoah 6/8/2018 8:23 PM 1
- 2. Content : Introduction Structure and preparation of DSSC Principles of DSSC Applications of DSSC Advantages and Disadvantages Conclusion 6/8/2018 8:23 PM 2
- 3. Introduction The increasingin global energy consumption 1998 - 12.7TW 2050 - expected around 26.4 to 32.9 TW 2100 - expected around 46.3 to 58.7 TW (Zulkifili, Kento, Daiki, & Fujiki, 2015) 6/8/2018 8:23 PM 3
- 4. Introduction Con’t Thepressure on natural sources of energy such as coal, petroleum and natural gas These forms of energy takes years to replenish once it is used up Hence the need to consider other sources of energy which is renewable 6/8/2018 8:23 PM 4
- 5. Introduction con’t Solarcell (photovoltaic cell) is the promising alternative for renewable energy A solar cell is a photovoltaic device that converts photons with specific wavelength into electricity It is classified into two: crystalline silicon thin film Both are constructed from semi-conductors including crystalline silicon compounds, cadmium telluride and copper indium selenide 6/8/2018 8:23 PM 5
- 6. Introduction con’t Dyesensitized solar cell (DSSC) is a relatively new kind of solar cell technology that shows great promise because of its low cost materials and simplicity DSSC is categorized under thin film considered as low cost energy conversion device with simple manufacturing procedures DSSC incorporates dye molecules into the wide band gap semi conductor electrodes (Titanium oxide) Michael Gratzel and co-workers (1991) were the pioneers in manufacturing DSSC called ‘Gratzel cell’ 6/8/2018 8:23 PM 6
- 7. Types of Dyesused in DSSC They constructed DSSC using nano-crystalline titanium oxide film with ruthenium based complexes Other dye types such as porphyrins, platinum complex also exist These dyes have better efficiency, high durability But high cost and possible degradation in the presence of water Highly toxic and carcinogenic 6/8/2018 8:23 PM 7
- 8. Why Ruthenium baseddyes? Ruthenium (Ru2+) as a second row transition metal ion has larger Δ◦ and small P values Bipy is also a strong field ligand which produces large Δ◦ values [Ru(bpy)3] 2+ is a d6 low spin complex which is diamagnetic It possess a singlet ground state and triplet excited state Radiative transition from triplet excited state to singlet ground state is quantum mechanically forbidden It therefore occurs at low efficiency and therefore allows electrons transfer 6/8/2018 8:23 PM 8
- 9.
- 10. Other forms ofdyes There was an introduction of natural dyes as sensitizers because of their Non-toxicity Easily available Easy to prepare Low cost Environmentally friendly Biodegradable Natural dye is capable of functioning as a dye sensitizer because of the presence of anthocyanin 6/8/2018 8:23 PM 10
- 11. Components of DSSC Semiconductor : Titanium oxide Sensitizer dye : porphyrins, platinum complexes Redox mediator : iodide Counter electrode (platinum) Mechanical support : glass coated with titanium oxide Binder : PEG 6/8/2018 8:23 PM 11
- 12. Operational principles ofDSSC 6/8/2018 8:23 PM 12 Fills the gab between the electrodes I3 - + 2e- 3I- (red) 3I- I3 - + 2e- (ox) The reduced part of the couple regenerates the photosensitized dye The formed oxide species diffuses to the counter electrode where it is reduced The redox couple I-/I3 affects the electrochemical potential of Titanium oxide electrode through the recombination kinetics between electrons in the titanium oxide and oxidized redox species (Boschloo, Hagfeldt, & Spectus, 2009) Schematic diagram of how the dssc operates
- 13. Why I-/I3 asredox couple? It yields the most stable forms of DSC It has good solubility It does not absorb too much light It has a suitable redox potential and provides rapid dye generation It is preferred to other redox mediators because of its slow recombination kinetics between electrons in titanium oxide and the oxidized part of the redox couple (Boschloo, Hagfeldt, & Spectus, 2009) 6/8/2018 8:23 PM 13
- 14. Applications of DSSC Architecture and urban planning ( eg buildings and houses) For agricultural purposes ( eg irrigation and green house For domestic purposes (eg heating, cooking etc) 6/8/2018 8:23 PM 14
- 15. Advantages of DSSC Lowcost of manufacturing Ability to work in wider angles and low light Long life span compared to other thin film solar cells Mechanically robust Pollution free No political interference Unlimited power Clean and easy to handle 6/8/2018 8:23 PM 15
- 16. Disadvantages of DSSC Not suitable for large scale purposes The use of liquid electrolytes which is unstable at varying temperatures The presence of VOC in electrolytes calls for proper sealing 6/8/2018 8:23 PM 16
- 17. Conclusion DSSC hasdemonstrated a very promising future in the field of energy due to its environmentally friendly nature and the easiness to construct Further more, the solar panel can be constructed in every location without connection to any power grid Initial construction is relatively expensive but once its done the solar energy is free It also has a long life span after installation 6/8/2018 8:23 PM 17
- 18. References Zulkifili, A.N. B., Kento, T., Daiki, M., & Fujiki, A. (2015). The Basic Research on the Dye-Sensitized Solar Cells (DSSC). Journal of Clean Energy Technologies, 3(5), 382– 387. https://doi.org/10.7763/JOCET.2015.V3.228 Boschloo, G., Hagfeldt, A., & Spectus, C. O. N. (2009). Characteristics of the Iodide / Triiodide Redox Mediator in Dye-Sensitized Solar Cells. Accounts of Chemical Research, 42(11), 1819–1826. https://doi.org/10.1021/ar900138m 6/8/2018 8:23 PM 18
- 19.
Editor's Notes
- #11 The presence of anthocyanin gives the photoactivity properties of natural dyes because they are capable of attaching to titanium oxide and injecting electrons into the conduction band of titanium oxide
- #12 The semiconductor has to be nano crystalline porous semiconductor which absorb dye, a counter electrode and an electrolyte of iodide triodide ions
- #13 The redox couple I-/I3 affects the electrochemical potential of Titanium oxide electrode through the recombination kinetics between electrons in the titanium oxide and oxidized redox species