Hybrids with Graphene for Optical Limiting Applications

1. Hybrids with Graphene for Optical Limiting Applications Pramod Gopinath Indian Institute of Space Science and Technology Valiamala, Thiruvananthapuram 695 547

2. IIST… Annual Photonics Workshop – February 28, 2014

3. Outline of the talk • Graphene – an Introduction • Methods of Graphene Preparation • Characterization of Graphene • Optical Limiting • Graphene • Graphene-C60 Hybrid • Polyaniline-Graphene Hybrid • ZnO-Graphene Hybrid • Conclusion Annual Photonics Workshop – February 28, 2014

4. 2010 Nobel Prize for Physics for ground breaking experiments regarding the two dimensional material graphene Konstantin Novoselov and Andre Geim Centre for Mesoscience and Nanotechnology and School of Physics and Astronomy, University of Manchester Annual Photonics Workshop – February 28, 2014

5. Graphene Sheet (2 D monolayer of carbon atoms) Fullerene 0 D Nanotube 1 D Graphite Sheet 3 D A. K. Geim & K. S. Novoselov. The rise of graphene. Nature Materials Vol . 6 ,183-191 (2007) Annual Photonics Workshop – February 28, 2014

6. Properties of Graphene Annual Photonics Workshop – February 28, 2014 Electronic Properties – High electron mobility (230,000 cm2/Vs) Thermal Properties - Thermal Conductivity ( 3000 W/mK) Mechanical Properties – Strength (130 GPa), Young’s modulus (~1.3 TPa) Optical Properties – 2.3% absorption of visible light Quantum Hall Effect – minimum Hall conductivity ~ 4 e2/h

7. Preparation of Graphene Annual Photonics Workshop – February 28, 2014 • Top down approach from Graphite • Micromechanical exfoliation • Creation of colloidal suspensions • Bottom up approach from carbon precursors • CVD • Organic synthesis • Epitaxial growth on insulating substrates

8. Preparation of Graphene Micromechanical exfoliation Annual Photonics Workshop – February 28, 2014

9. Preparation of Graphene Annual Photonics Workshop – February 28, 2014 Graphite flakes are combined with sodium cholate in aqueous solution Green and Hersam, Nano Letters, 9, 4031 (2009)

10. Preparation of Graphene Annual Photonics Workshop – February 28, 2014 Roll based production of graphene films on copper foil

11. Preparation of Graphene NATURE, Vol , 458, 16 , April (2009) Annual Photonics Workshop – February 28, 2014 From Carbon nano tubes

12. Preparation of Graphene Oxidation (Hummers’method) Graphite Oxide H2SO4/ KMnO4 H2SO4/KClO3 Or H2SO4/HNO3 ………………. H2O Ultrasonication (exfoliation) Fuctionalization (for better dispersion) Graphene Oxide monolayer or few layers Chemical reduction to restore graphitic structures Making composite with polymers Making composite with polymers Annual Photonics Workshop – February 28, 2014

13. Graphene - Characterization Optical Microscopy Image of Single, Double and Triple layer Graphene on Si with a 300 nm SiO2 over layer Annual Photonics Workshop – February 28, 2014

14. Graphene - Characterization Atomic Force Microscopy Images of unreduced and chemically reduced graphene oxide nanosheets deposited from aqueous dispersions Annual Photonics Workshop – February 28, 2014

15. Graphene - Characterization Flourescence Quenching Microscopy Image showing G-O single layer deposited on a SiO2 /Si wafer applying a 30 nm thick fluorescein/PVP layer Annual Photonics Workshop – February 28, 2014

16. Graphene - Characterization Transmission Electron Microscopy Image of a single layer Graphene membrane Step from a monolayer to a bilayer Annual Photonics Workshop – February 28, 2014

17. Graphene - Characterization Raman Spectroscopy D – 1350 cm-1 G – 1580 cm-1 2D – 2700 cm-1 D band – presence of disorder in atomic arrangement or edge effect G band – in plane vibration of sp2 carbon atoms 2D band – second order Raman scattering Annual Photonics Workshop – February 28, 2014

18. Nonlinear Optical Materials Saturable Absorbers which give increased transmittance at high optical intensities or fluences, and are useful for pulse compression, Q-switching and mode-locking Optical Limiters Which give decreased transmittance, and are useful for pulse shaping, mode locking and for the protection of eyes and sensor focal-plane arrays Progress in development of Optical limiters with large NLO responses in carbon-based materials like, graphitic systems, single-walled CNTs, small π-electron systems like fullerenes, porphyrins and phthalocyanines Challenge: Development of materials that can be processed as stable solutions or liquid dispersions that can ultimately be formed into films for practical applications Annual Photonics Workshop – February 28, 2014

19. Optical Limiting Open aperture Z-scan technique • Sheik-Bahae, M., et al. IEEE J. of Quantum Electron., 26(4): 760-769 (1990). Annual Photonics Workshop – February 28, 2014

20. Optical Limiting Open aperture Z-scan plot Optical limiting plot where • z0 is the Rayleigh length. • R is the Fresnel reflectance of the sample surface • Leffis given by α is the linear absorption coefficient L is the thickness of the sample • R. L. Sutherland, Handbook of Nonlinear Optics, second ed., Marcel Dekker, New York, 2003. Annual Photonics Workshop – February 28, 2014

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25. Graphene – C60 Hybrid Annual Photonics Workshop – February 28, 2014

26. Graphene-Polyaniline Hybrid AlenHeeger A.J.MacDiarmid H.Shirakawa Annual Photonics Workshop – February 28, 2014 2000 Nobel Prize

27. Polyaniline-Graphite oxide hybrid – In-situ polymerization of aniline in the presence of synthesized graphite oxide Synthesis of graphite oxide (GO) Low temperature modified Hummers method Characterization Annual Photonics Workshop – February 28, 2014

28. SEM image TEM image AFM image 2 nm 2 nm Annual Photonics Workshop – February 28, 2014

29. Synthesis of polyaniline-graphite oxide hybrid In-situ polymerization of aniline in presence of GO Various compositions : PxGy, (x =proportion of aniline, y= proportion of GO)- P4G1, P2G1, P1G1, and P1G2 Annual Photonics Workshop – February 28, 2014

30. SEM images Polyaniline P1G2 AFM image 5 µm 500 nm TEM image HRTEM image 3.2 nm 1 nm Annual Photonics Workshop – February 28, 2014

31. Nonlinear optical properties Annual Photonics Workshop – February 28, 2014

32. Polyaniline-phenylene diamine functionalized reduced graphene oxide hybrids Synthesis of phenylene diamine modified reduced graphene oxide (GONH2) Annual Photonics Workshop – February 28, 2014

33. TEM image SEM image 5 µm Annual Photonics Workshop – February 28, 2014

34. Synthesis of polyaniline-phenylene diamine modified reduced graphene oxide hybrid GONH2 to aniline ratio 1:2 1:1 2:1 Annual Photonics Workshop – February 28, 2014

35. SEM image TEM images Annual Photonics Workshop – February 28, 2014

36. Remyamol T, Pramod Gopinath, Honey John. Synthesis and nonlinear optical properties of reduced graphene oxide covalently functionalised with polyaniline. Carbon 59 (2013) 308-314. Annual Photonics Workshop – February 28, 2014

37. Covalently grafted polyaniline- reduced graphene oxide hybrid Synthesis of polyaniline-reduced graphene oxide hybrid Annual Photonics Workshop – February 28, 2014

38. SEM image TEM image Annual Photonics Workshop – February 28, 2014

39. Remyamol T, Pramod Gopinath, Honey John. Grafting of self assembled polyaniline nanorods on reduced graphene oxide for nonlinear optical application. Synthetic Metals 185-186 (2013) 38-44. Optical limiting plots Open aperture Z-scan plots Annual Photonics Workshop – February 28, 2014

40. Reduced Graphene oxide-ZnO Hybrid Reduced graphene oxide –ZnO hybrid is synthesized by two routes: Hydrothermal Synthesis Solution precipitation technique Annual Photonics Workshop – February 28, 2014

41. Zn(Ac)2 (1 mmol)CH3COOH Polyvinylpyrrolidone (PVP) (0.05 %) Zn(Ac)2- PVP complex NaOH Reduced Graphene oxide-ZnO Hybrid Different weight ratios of GO Dispersed by sonication for 8 h Followed by stirring for 16h ZnO/GO colloid Stirred at room temperature for 12 h (solution precipitation) S-rGO-ZnO-x Annual Photonics Workshop – February 28, 2014 Kept in autoclave at different temperature for 7 h @ 100oC (hydrothermal method) H-rGO-ZnO-x

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43. IR and Raman spectra of H-rGO-ZnO and S-rGO-ZnO • Decrease of oxygen functional groups in hybrid • in both the samples peak at 1730 cm-1 • (C=O stretching vibrations of the –COOH groups) is absent • For S-rGO-ZnO, peak at 1680 cm-1 indicate C=O in conjugation with C=C • ID/IG ratios 0.94 and 1.03 for H-rGO-ZnO and S-rGO-ZnO • Restacking of exfoliated graphene sheets are prevented by the • as-grown ZnOnanoparticles Annual Photonics Workshop – February 28, 2014

44. compared to bare ZnO and GO, hybrid shows enhanced • nonlinear optical properties • photoinduced electron transfer and energy transfer • For hydrothermally synthesized hybrid, more extended • -conjugation results in enhanced NLO properties Annual Photonics Workshop – February 28, 2014

45. Conclusion Lot of scope for further work in Hybrids as the optical limiting properties can be enhanced by suitably modifying the functionalities Annual Photonics Workshop – February 28, 2014

46. A word of Gratitude…… Collaborators: 1. Dr. Honey John, Department of Chemistry, IIST 2. Dr. Reji Philip, Raman Research Institute Research Students: 1. Ms. Remyamol T 2. Ms. Kavitha M K Annual Photonics Workshop – February 28, 2014

47. Thank you for listening Annual Photonics Workshop – February 28, 2014