Dssc (Dye sensitized solar cell)

introduction to DSSC, Principle and working of DSSC,Component involved in DSSC, how does DSSC work?,Advantage and disadvantage of DSSC, application of DSSC.

1. DSSC (Dye Sensitized Solar Cell) Submitted by: Preeti choudhary ( 17/MAP/016 ) M.Sc.(Applied Physics )

2. content Introduction to DSSC •  Principle and working of DSSC •  Component involved in DSSC •  How Does DSSC work? Advantage and Disadvantage •  Application

3. Renewable energy sources such as solar energy are considered as a feasible alternative because “ More energy from sunlight strikes Earth in 1 hour than all of the energy consumed by humans in an entire year .”(Lewis, 2007). • The use of natural dye extracts provides natural, non toxic and low cost dye sources with high absorbance level of UV, visible and near IR. • Examples of such dye sources are Bahraini Henna ( Lawsonia inermis L .) and Bahraini raspberries ( Rubus spp.). Introduction

4. Disadvantages of Conventional Solar cells o C ostly equipment o Environmental Impact of PV Cell Production o Initial cost is very high o Requires expert hand and equipment in manufacture

5. Semiconductor Solar Cells DSSC Transparency Opaque Transparent Environment(Material& Process) Normal Great Power Generation cost High Low Power Generation efficiency High Normal Color Limited Various

6. What is a DSSC? A dye sensitized solar cell is a new kind of relatively low cost solar cell with great potential as its materials are considerably cheaper and it is simple to make.

7. Past • Michael Grätzel and Brian O’Regan invented “Dye- sensitized solar cells”, also called “Grätzel cells”, in 2005. • The first cells were only capable of using light at the Ultraviolet and Blue end of the spectrum. • By the turn of the century, advances in technology were able to broaden the frequencies in which these cells were able to respond. • The most efficient of the dyes were simply known as “Black dyes” due to their very dark colors.

8. C omponents The DSSC device consists of 4 components : Semiconducting electrode n-type TiO and p-type NiO Dye-sensitizer Light harvesting and electronic transition Redox mediator I - / I 3 - or Co II / Co III complexes Counter electrode Carbon or Pt

9. 1. Transparent substrate for both the conducting electrode and counter electrode • Clear glass substrates are commonly used as substrate because of their relative low cost, availability and high optical transparency in the visible and near infrared regions of the electromagnetic spectrum. • TCFs for photovoltaic applications have been fabricated from both inorganic and organic materials. • Inorganic films typically are made up of a layer of transparent conducting oxide (TCO),generally in the form of indium tin oxide (ITO), fluorine doped tin oxide (FTO), and doped zinc oxide.

10. 2.Nanostructured photoelectrode • In the old generations of photo electro chemical solar cells (PSC) photo electrodes were made from bulky semiconductor materials such as Si, GaAs or CdS. • However, these kinds of photo electrodes when exposed to light they undergo photo corrosion that results in poor stability of the photoelctrochemical cell. • The use of sensitized wide bandgap semiconductors such as TiO ₂ , or ZnO resulted in high chemical stability of the cell due to their resistance to photo corrosion.

11. • The problem with bulky single or poly-crystalline wide band gap is the low light to current conversion efficiency mainly due to inadequate adsorption of sensitizer because of limited surface area of the electrode. • One approach to enhance light-harvesting efficiency (LHE) and hence the light to current conversion efficiency is to increase surface area (the roughness factor) of the sensitized photo electrode.

12. 3.Photosensitizer • Dye molecules of proper molecular structure are used to sensitized wide bandgap nanostructured photoelectrode. • Upon absorption of photon, a dye molecule adsorbed to the surface of say nanostructured TiO ₂ gets oxidized and the excited electron is injected into the nanostructured TiO ₂ . • Sensitizations of natural dye extracts such as shiso leaf pigments, Black rice, Fruit of calafate, Rosella ,Natural anthocyanins ,Henna and wormwood have been investigated and photovoltaic action of the tested cells reveals some opportunities.

13. Redox electrolyte • Electrolyte containing I ⁻ / 3 I ⁻ oxidized dye molecules redox ions is used in DSSC to regenerate the • This will complete the electric circuit by mediating electrons between the nanostructured electrode and counter electrode. • Cell performance is greatly affected by ion conductivity in the electrolyte which is directly affected by the viscosity of the solvent. • NaI, LiI and R ₄ NI (tetraalkylammonium iodide) are well known examples of mixture of iodide usually dissolved in nonprotonic solvents such as acetonitrile, propylene carbonate and propionitrile to make electrolyte. • The redoxing electrolyte needs to be chosen such that the reduction of I ions by injection of electrons is fast and efficient 3 Dye-Sensitized Solar Cells: A Successful Combination of Materials Claudia Longo and Marco-A. De Paoli* Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13084-971 Campinas - SP , Brazil

14. Mechanism

15. Dye Sensitized Solar Cells - Working Principles, Challenges and Opportunities Khalil Ebrahim Jasim Department of Physics, University of Bahrain Kingdom of Bahrain Schematic of the structure of the dye sensitized solar cell.

16. Illustration of operation principle of dye sensitized solar cell

17. TiO 2 Dye Electrolyte Cathode Wide band-gap semiconductor How Does DSSC Work?

18. -0.5 0.5 TiO 2 1.0 S* S ° /S + Dye Electrolyte Ox Red Cathode Electron energy (eV vs. NHE) -1.0 e - Wide band-gap semiconductor How Does DSSC Work?

19. 1. Light absorption -0.5 0.5 TiO 2 1.0 S* S ° /S + hν Dye Electrolyte Ox Red Cathode 1 Electron energy (eV vs. NHE) -1.0 e - Wide band-gap semiconductor h + How Does DSSC Work?

20. 1. 2. Light absorption Injection to semiconductor 3. Percolation -0.5 0.5 TiO 2 1.0 S* S ° /S + hν Dye Electrolyte Ox Red Cathode 1 2 3 Electron energy (eV vs. NHE) -1.0 e - Wide band-gap semiconductor h + How Does DSSC Work?

21. 1. 2. Light absorption Injection to semiconductor Percolation 3. 4. Regeneration of oxidized dye -0.5 0.5 TiO 2 1.0 S* S ° /S + hν Dye Electrolyte Ox Red Cathode 1 2 3 4 Electron energy (eV vs. NHE) -1.0 Wide band-gap semiconductor e - h + How Does DSSC Work?

22. 1. 2. Light absorption Injection to semiconductor Percolation 3. 4. Regeneration of oxidized dye 5. Regeneration of oxidized species -0.5 0.5 TiO 2 1.0 S* S ° /S + hν Dye Electrolyte Ox Red Cathode LOAD e - External circuit 1 2 3 4 Electron energy (eV vs. NHE) -1.0 Wide band-gap semiconductor h + 5 h + e - How Does DSSC Work?

23. Maximum Voltage in DSSCs -0.5 0.5 TiO 2 1.0 S* S ° /S + Dye Electrolyte Ox Red Maximum Voltage Cathode LOAD e - External circuit Electron energy (eV vs. NHE) -1.0 e - Wide band-gap semiconductor The voltage is determined mainly by the titania and redox couple in the electrolyte. h +

24. Natural Dye Performances Dye-Sensitized Solar Cells: A Successful Combination of Materials : Claudia Longo and Marco-A. De Paoli* Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13084-971 Campinas - SP, Brazil Measured absorbance of some extracted natural dyes in methanol as solvent.

25. The DSC vs. Conventional Silicon PV TiO 2 Dye Electrolyte Cathode + n-type Silicon p-type Silicon + + + + • Charge carriers (excited electrons) are produced throughout the semiconductor • Semiconductor considerations: • Precise doping • high purity • high crystalinity • Light absorption and charge transport are decoupled • Relaxed constraints on individual components (each can be separately tuned) • Only monolayer of dye on TiO 2

26. Applications Of DSSC • Because of the physical nature of the dye sensitized solar cells, inexpensive, environment friendly materials, processing, and realization of various colors, power window and shingles are prospective applications in building integrated photovoltaics • The availability of lightweight flexible dye sensitized cells or modules are attractive for applications in room or outdoor light powered calculators, gadgets, and mobiles. • Flexible dye sensitized solar modules opens opportunities for integrating them with many portable devices, baggage, gears, or outfits. • In power generation, dye sensitized modules with efficiency of 10% are attractive choice to replace the common crystalline Si-based modules.

27. Applications of DSSC (a) 200 m 2 of DSSC panels installed in Newcastle (Australia)– the first commercial DSSC module

28. (c) flexible DSSC-based solar module developed by Dyesol ( http://www.dyesol.com ) (d) jacket commercialized by G24i (http://www.g24i.com). D

29. Solar Cell Efficiencies Silicon Solar Cell Efficiencies: Theoretical Maximum: 26% Best in Lab: 25% (Green, UNSW) Modules: 15-22% Thin Film Solar Cell Efficiencies: Theoretical Maximum: >22% Best in Lab: 20% (Noufi, NREL) Modules: 9-12% Dye-Sensitized Solar Cell Efficiencies: Theoretical Maximum: 14-20% Best in Lab: 12% (Grätzel, EPFL) Modules: 6-9%

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31. Advantage Less Expensive Work in low light conditions High performance-price ratio A variety of colours

32. Disadvantage Lower efficiencies Breakdown of the Dye Liquid Electrolyte may leak

33. Reference • Gratzel, M. (2005). Solar Energy Conversion by Dye-Sensitized Photovoltaic Cells. Inorg. Chem., Vol. 44, pp. 6841-6851. • • • • Lewis, N. S. (2007). Toward Cost-Effective Solar Energy Use. Science, Vol 315, pp. 798-801. Meyer, G. J. Inorg. Chem. 2005, 44, 6852. Mallouk, T. E.; Hoertz, P. G. Inorg. Chem. 2005, 44, 6828. Nakade, S.; Kubo, W.; Saito, Y.; Kanzaki, T.; Kitamura, T.; Wada, Y.; Yanagida, S. J. Phys. Chem. B 2003, 107. • • • • • • Plass, R.; Pelet, S.; Kruger, J.; Gratzel, M.; Bach, U. J. Phys. Chem. B 2002, 106, 7578. Nozik, A. J. Quatum dot solar cells. Next Gener. Photovoltaics 2004, 196. Liska er al. 2006, 88, 203103. Marcus, R. A. 1992, Nobel Lecture. Bernards, D. A.; Samuel, F. T.; Hector, D. A.; George, G. M. Science, 2006, 313, 1416. Amao, Y. & Komori, T. (2004). Bio-photovoltaic conversion device using chlorine-e6 derived from chlorophyll from Spirulina adsorbed on a nanocrystalline TiO2 film electrode. Biosensors Bioelectronics, Vol. 19, Issue 8, pp. 843-847. • Harding, H.E.; Hoke, E.T.; Armistrong, P.B.; Yum, J.; Comte, P.; Torres, T.; Frechet, J.M.J.; Nazeeruddin, M.K.; Gratzel, M. & McGehee, M.D. (2009). Increased light harvesting in dye- sensitized solar cells with energy relay dyes. Nature Photonics, Vol. 3, pp. 406-411. 72

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