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differantes types of organic solar cells and applications
- 1. 1 Academic year 2016/2017 Republic of Tunisia University of Sousse Higher Institute of Applied Sciences and Technology Organic photovoltaic cells : OPV Elaborated by : TALBI Malek El –AGUECH Mohamed Amin JEDIDI Sahar Supervised by: Pr. DRIDI Cherif
- 2. 2 Introduction How it works Advantages and limits Conclusion Definition Applications
- 3. 3 • The Earth receives 174,000 (TW) of incoming solar radiation at the upper atmosphere, so as a solution the sun became an important source of renewable energy . Classic solar panel •Through the ages mankind needed more and more energy. • Oil, gas and coal will not last forever and it takes a number of years until new fossil fuels are formed.
- 4. 4 Organic photovoltaic (OPV) solar cells aim to provide an Earth-abundant and low-energy- production photovoltaic (PV) solution. Why Organic solar cells ? This New technology also has the theoretical potential to provide electricity at a lower cost than the classical solar cells ( inorganic pv cells)
- 5. 5 Introduction How it works Advantages and limits Conclusion Definition Applications
- 6. 6 •An organic solar cell device or organic photovoltaic cell (OPVC) is a class of solar cell that uses conductive organic polymers or small organic molecules for light absorption and charge transport.
- 7. 7 • Processes occurring in an organic solar cell:
- 8. 8 Organic photovoltaic solar cells Single layer organic cells Bilayer organic cells Bulk heterojunction organic cells Electrode 1 (ITO) Semiconducting polymer Electrode 2 (Al,Mg,Ca) Electron acceptor Electron donor PEDOT Electrode 1 (ITO) Electrode 1 (ITO) Electrode 2 (Al,Mg,Ca) Electrode 2 (Al,Mg,Ca)
- 9. 9 Introduction How it works Advantages and limits Conclusion Definition Applications
- 10. 10 • Single layer organic cells : Substrate Semiconducting polymer Electrode 1 (ITO) Electrode 2 (Al,Mg,Ca) Once an external circuit is made by connecting the two electrodes with a conductor, the difference in the work functions creates an electric field in the organic layer
- 11. 11 Electrons are excited to the LUMO leaving hole in the HOMO Excitons Electric field in the organic layer : -Break up the excitons pairs. -Pulling electrons to the positive electrode. -Pulling holes to the negative electrode
- 12. 12 • Bi-layer organic cells : In a bilayer OPV cell we have more layers: Donor layer Acceptor layer
- 13. 13 The layer with higher electron affinity and ionization potential is the electron acceptor, and the other layer is the electron donor. Bi-layer cells splits excitons give are much more efficiently
- 14. 14 • Bulk heterojunction organic cells : In a Bulk heterojunction organic cells we find 2 transparent electrods 1 active layer
- 15. 15 In charge transfer, both donors contribute directly to the generation of free charge carriers. Holes pass through only one donor domain before collection at the anode. In energy transfer, only one donor contributes to the production of holes. The second donor acts solely to absorb light, transferring extra energy to the first donor material. In parallel linkage, both donors produce excitons independently, which then migrate to their respective donor/acceptor interfaces and dissociate ow
- 16. 16 Introduction How it works Advantages and limits Conclusion Definition Applications
- 17. 17 Advantages and limits Single layer organic cells Simple fabrication Low quantum efficiency and coversion efficiency: Exciton pairs not effectivly separated. Advantages : Disadvantages : The elctron-hole recombination process is high: electrons and holes travel in the same material
- 18. 18 Advantages and limits Bi-layer organic cells Small interface that allows only excitons of a thin layer to reach it and get dissociated. Disadvantages : The diffusion length of excitons is on the order of 4-10 nm.
- 19. 19 Advantages and limits Bulk heterojunction organic cells Fullerenes (PCBM ) : -Absorb very weakly visible light. - Poor electronic tunability. . Disadvantages : Replace these fullerenes with organic molecules Structural formula of phenyl-C61-butyric acid methyl ester
- 20. 20 Advantages and limits Organic photovoltaic cells: Advantages: Flexibility : roll to roll production Low cost and light weight Ease of integration Ecological and economic benefits Semitramsparent
- 21. 21 Advantages and limits Organic photovoltaic cells: Disadvantages: Low efficiency: only 5% efficiency compared to the 15% of silicon cells Low liftime < 10 000h Low yield
- 22. 22 Advantages and limits Organic pv Inorganic pv Lifetime 10 000 h 10 years Yield 5% to 11 % 11% 15% 25% Cost Low hight Transparency Transparent Opaque Integration Easy Not easy Flexibility Flexibl Not flexible
- 23. 23 Introduction How it works Advantages and limits Conclusion Definition Applications
- 24. 24 Applications Personal mobile phone charger. BIV(building integrated photovoltaics). Clothes with embedded cells
- 25. 25 Introduction How it works Advantages and limits Conclusion Definition Applications
- 26. 26 Organic photovoltaic energy have the potential to be part of the world’s solution to the future of energy. New generation of microelectronics : electronics everywhere
- 27. 27 The organic solar energy research is developing: Reaserchers investigated the possibility to use liquid crystal semiconductor molecules in order to get bulk-ordered separated structures of p and n to obtain a better bulk architecture. The key to future improvements in this field lies in better understanding the materials involved and their structures.
- 28. 28 [1] Askari Mohammad Bagher. Comparison of Organic Solar Cells and Inorganic Solar Cells. International Journal of Renewable and Sustainable Energy. Vol. 3, No. 3, 2014, pp. 53-58. doi: 10.11648/j.ijrse.20140303.12 [2] Pulfrey, L.D. (1978). Photovoltaic Power Generation. New York: Van Nostrand Reinhold Co. [3] M.G. Zebaze Kana. Introduction to Organic Solar Cell Devices & Electrical Characterization . September 16, 2011 [4] Krebs et. al., Solar Energy Materials and Solar Cells 2009
- 29. 29 Thank you for your attention !
Editor's Notes
- It is an important source of renewable energy , We all know about the classic pv in which we use this kind of panels, In our presentation we will deal with the organic solar cells :
- Its the new generation of solar cells with very lower cost comparing with the classical solar cells.
- An organic solar cell device or organic photovoltaic cell (OPVC) is a class of solar cell that uses conductive organic polymers or small organic molecules for light absorption and charge transport. These devices are relatively easy to fabricate, can also be processed on flexible substrates, however they have relatively low conversion efficiencies and offer low stability . This is an example of a structure of a planar organic photovoltaic device . We obtain these layers with different methods of depositions like : -the ITO by sputtring -organic layers by spin coating -the electrodes by evaporation
- A photon is absorbed in the polymer, thus creating an exciton. • The nascent exciton dissociates into separated charge carriers. This process is facilitated by the presence of an electron acceptor, which accepts the electron while the hole remains on the polymer chains. • The difference in work functions of the electrodes gives rise to an electric field which drives the separated charge carriers towards electrodes. • The charge carriers are collected at the electrodes. If an electrical circuit is connected to the electrodes, an electrical current flows through it.
- There are 3 types of opv : Here are the basic structres of each cell Single layer organic photovoltaic cells are the simplest form. These cells are made by sandwiching a layer of organic electronic materials between two metallic conductors, typically a layer of indium tin oxide (ITO) and a layer of metal such as Aluminum, Magnesium or Calcium. 2) The double layer organic solar cell improves the functionality of the single layer OPV by including a distinct organic Donor layer and a distinct Acceptor layer between the two previous electrodes.. 3) Bulk heterojunctions : Instead of having distinct donor and distinct acceptor layers, in the blend layer solar cell device, the electron donor and acceptor are mixed together, forming a polymer blend.
- Now let’s spicify how each type works : 1) Single layer organic cells : Once an external circuit is made by connecting the two electrodes with a conductor, the difference in the work functions creates an electric field in the organic layer.
- *upon absorption of light, the electrons are excited to the LUMO leaving hole in the HOMO, forming excitons, the electric field in the organic layer will therefore help to break up the exciton pairs, pulling electrons to the positive electrode and holes to the negative electrode. *Single layer organic solar cells are also refered to as Schottky diode since the rectification occurs at only one interface (organic layer / metal electrode), the other electrode forming and ohmic contact with the organic semiconductor.
- In a bilayer OPV cell, sunlight is absorbed in the photoactive layers composed of donor and acceptor semiconducting organic materials to generate photocurrents. The donor material(D) donates electrons and mainly transports holes and the acceptor material (A) withdraws electrons and mainly transports electrons. Lack of electrons,
- In the case of Bi-layer cells splits excitons are much more efficiently than single layer photovoltaic cells. This structure is also called a planar donor-acceptor heterojunction.
- After the capture of a photon, electrons move to the acceptor domains, then are carried through the device and collected by one electrode, and holes move in the opposite direction and collected at the other side. If the dispersion of the two materials is too fine, it will result in poor charge transfer through the layer.
- This class of solar cell though simple to fabricate has low quantum efficiency and conversion efficiency. The drawback is due to the fact that the electric field (in the organic layer) resulting from the difference in work functions of the two electrode is usually not sufficient to achieve an effective separation of the exciton pairs. • There is rather an electron-hole recombination process in the organic layer. Furthermore, in the single layer device both the electrons and the holes travel in the same material and recombination losses are generally high
- Fullerenes (a molecule of carbon )such as PC71BM are often the electron acceptor materials found in high performing bulk heterojunction solar cells. However, these electron acceptor materials very weakly absorb visible light, decreasing the volume fraction occupied by the strongly absorbing electron donor material. Furthermore, fullerenes have poor electronic tunability, resulting in restrictions placed on the development of conjugated systems with more appealing electronic structures for higher voltages. Recent research has been done on trying to replace these fullerenes with organic molecules that can be electronically tuned and contribute to light absorption. * As an exemple this is a spherical fullerenes also reffered as buckyballs
- In summury : Ultra flexible and even stretchble Envirementlty friendly materials semitramsparent
- * The next generation of microelectronics is aiming for applications of electronics everywhere * BIV(building integrated photovoltaics) such as building’s exterior wall and windows. Clothes with embedded cells are also possible And athors applications fields The present situation indicates that organic solar cells cannot substitute for silicon cells in the energy conversion field. However their use seems to be more targeted towards specific applications such as recharging surfaces for laptops, phones, clothes, and packages, or to supply the power for small portable devices, such as cellphones and MP3 players. Other than the domestic use, recent developments have shown a military application potential for organic solar modules. Research in the US (Konarka) has shown that organic cells can be used in soldier tents to generate electricity and supply power to other military equipment such as night vision scopes and GPS (global positioning system) receivers. This technology is thought to be extremely valuable for demanding missions.
- As a concluding remark of this brief review concerning organic solar cell : Organic photovoltaic energy have the potential to be part of the world’s solution to the future of energy also The new generation of microelectronics is aiming for applications of electronics everywhere thanks to flexibility and light weight
- , we like to stress the fact that this field of research is in developing. Efforts need to be done in order to get bulk-ordered separated structures of p and n organic semiconductors in order to improve contemporaneously both the charge separation processes and the transport of the free charge to the electrodes. In our opinion one of the most promising work directions is to investigate the possibility to use liquid crystal semiconductor molecules and to study phase separation strategies between these base components, in order to obtain fine cell bulk architectures