1. NESLHAN YAMUR 23/01/2013 POLYMERIC MATERIALS FOR ORGANIC SOLAR CELLS 1

2. Organic Photovoltaic Cells Organic photovoltaic cells are solar cells that utilize organic polymers and small molecules as the active layer for light absorption and charge transport http://www.solarcell.net.in/2 3. Organic Photovoltaic Cells Solar cells are designed using a p- n junction with both n and p-type materials such that the free holes and electrons flow in opposite directions, producing a direct current. http://www.solarcell.net.in/3 4. The Steps for the Charge Transfer 1) Excitation on donor 2) Excitation delocalized on a donor-acceptor complex 3) Charge-transfer initiated. 4) Charge separation. 4 5. Diagram of the Donor and Acceptor 5 6. Advantages of Polymeric Materials Compared to silicon structures, organic materials have several advantages: 1) Low cost of the technology 2) Possible to achieve fully flexible structures, 3) Relatively low voltages. 6 7. Polymeric Materials Materials having a delocalized electron system can absorb sunlight, create photogenerated charge carriers, and transport these charge carriers. Organic solar cells generally focuses either on solution processable organic semiconducting polymers. 7 8. Donor (P-Type) Examples 8 9. Polymeric Materials as Donor 1. Phthalocyanine 2. Poly(3-hexylthiophene) P3HT 9 10. 1. Phthalocyanine C32H18N8 Molecular Mass: 514.54 g mol1 10 11. 1. Phthalocyanine Hazards: Do not breathe dust Avoid contact with skin Avoid contact with eyes 11 12. 1. Phthalocyanine Unsubstituted phthalocyanines strongly absorb light between 600 and 700 nm, thus these materials are blue or green. Substitution can shift the absorption towards longer wavelengths, changing the color from pure blue to12 13. 2. Poly(3-hexylthiophene) P3HT (C10H14S)n Melting Point: 238 C High molecular weight http://www.1-material.com/node/31 13 14. Acceptor (N-Type) Examples 14 15. Polymeric Materials as Acceptor 1. Perylene 2. Perylene-3,4,9,10-tetracarboxylic dianhydride PTCDA 3. Phenyl-C61-butyric acid methyl ester PCBM 4. Buckminsterfullerene C60 15 16. 1. Perylene C20H12 Molar mass: 252.31 g mol1 Melting Point: 276- 279 C S. Gne, H. Neugebauer, Conjugated Polymer-Based Organic Solar Cells, 2007 16 17. 1. Perylene The perylene molecule consists of two naphthalene mole cules connected by a carbon-carbon bond at the 1 and 8 positions on both molecules. All of the carbon atoms in perylene are sp2 hybridized.S. Gne, H. Neugebauer, Conjugated Polymer-Based Organic Solar Cells, 200717 18. 1. Perylene It or its derivatives may be carcinogenic Do not breathe dust Avoid contact with skin Avoid contact with eyes . http://en.wikipedia.org/wiki/Perylen e 18 19. 1. Perylene It has an absorption maximum at 434 nm. http://en.wikipedia.org/wiki/Perylen e 19 20. 2. Perylene-3,4,9,10-tetracarboxylic dianhydride PTCDA C24H8O6 Molar Mass: 392.32 g mol -1 Melting Point: > 300 C 20 21. 2. Perylene-3,4,9,10-tetracarboxylic dianhydride PTCDA Harmful if swallowed May cause respiratory irritation. Avoid breathing dust / fume / gas / mist / vapors / spray. 21 22. 3. Phenyl-C61-butyric acid methyl ester PCBM C72H14O2 Molar Mass: 910.88 g mol1 22 23. 3. Phenyl-C61-butyric acid methyl ester PCBM It is a more practical choice for an electron acceptor when compared with fullerenes because of its solubility in chlorobenzene. This allows for solution processable donor/acceptor mixes, a necessary property for "printable" solar cells.23 24. 4. Buckminsterfullerene C60 C60 Molar Mass: 720.64 g mol1 Density: 1.65 g/cm3 Melting Point: sublimates at ~600 C S. Gne, H. Neugebauer, Conjugated Polymer-Based Organic Solar Cells, 2007 24 25. 4. Buckminsterfullerene C60 The C60 molecule is extremely stable, being able to withstand high temperatures and pressures. S. Gne, H. Neugebauer, Conjugated Polymer-Based Organic Solar Cells, 2007 25 26. References S. Gunes, H. Neugebauer, Conjugated Polymer- Based Organic Solar Cells, 2007 A. Moliton1, R. Hiorns, Review of electronic and optical properties of semiconducting -conjugated polymers: applications in optoelectronics, 2004 A. Facchetti, -Conjugated Polymers for Organic Electronics and Photovoltaic Cell Applications, Northwestern University, 2011 www.wikipedia.com 26 27. Thank You for Your Attention 27