hybrids with graphene for optical limiting applications

Hybrids with Graphene for

Optical Limiting Applications

Pramod Gopinath

Indian Institute of Space Science and TechnologyValiamala, Thiruvananthapuram 695 547

Annual Photonics Workshop – February 28, 2014

IIST…


● Graphene – an Introduction● Methods of Graphene

Preparation● Characterization of Graphene● Optical Limiting● Graphene● Graphene-C60 Hybrid● Polyaniline-Graphene Hybrid● ZnO-Graphene Hybrid● Conclusion

Outline of the talk

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



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)

Graphene Sheet (2 D monolayer of carbon atoms)


Properties of Graphene

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


Preparation of Graphene

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



Micromechanical exfoliation



Graphite flakes are combined with sodium cholate in aqueous solution

Green and Hersam, Nano Letters, 9, 4031 (2009)



Roll based production of graphene films on copper foil



From Carbon nano tubes

NATURE, Vol , 458, 16 , April (2009)



Oxidation (Hummers’method)

H2SO4/ KMnO4

H2SO4/KClO3

Or H2SO4/HNO3

………………. H2O

Ultrasonication (exfoliation)

Graphite Oxide

Graphene Oxidemonolayer or few layers

Fuctionalization (for better dispersion)

Chemical reduction to restore graphitic structures

Making composite with polymersMaking composite with polymers


Graphene - Characterization

Optical Microscopy

Image of Single, Double and Triple layer Graphene on Si with a 300 nm SiO2 over layer



Atomic Force Microscopy

Images of unreduced and chemically reduced graphene oxide nanosheets deposited from aqueous dispersions



Flourescence Quenching Microscopy

Image showing G-O single layer deposited on a SiO2 /Si wafer applying a 30 nm thick fluorescein/PVP layer



Transmission Electron Microscopy

Image of a single layer Graphene membrane

Step from a monolayer to a bilayer



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


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


Optical Limiting

Open aperture Z-scan technique

Sheik-Bahae, M., et al. IEEE J. of Quantum Electron., 26(4): 760-769 (1990).


Optical Limiting

dtezqzq

SzT t2

0,1ln0,11, 0

0 2

02

00 1)1()0,( zzLIRzq eff where

α is the linear absorption coefficientL is the thickness of the sample

-12 -8 -4 0 4 8 12

0.6

0.8

1.0T no

rm

z(mm)1.3x1011 1012 6x1012

0.6

0.8

1.0

T nor

m

Input intensity (W/m2)

Open aperture Z-scan plot Optical limiting plot

R. L. Sutherland, Handbook of Nonlinear Optics, second ed., Marcel Dekker, New York, 2003.

z0 is the Rayleigh length.R is the Fresnel reflectance of the sample surfaceLeff is given by ]1[ Le


Graphene – C60 Hybrid


Graphene-Polyaniline Hybrid

Alen HeegerA.J.MacDiarmidH.Shirakawa

2000 Nobel Prize


Synthesis of graphite oxide (GO)Low temperature modified Hummers method

CharacterizationPeak position (cm-

1)Assigned vibrations

1729 C=O stretching

1399 Carboxy C-O stretching

1186 Epoxy C-O-C stretching

1084 Alkoxy C-O stretching

1632 Unoxidized C=C stretching

>3000 O-H stretching

35

40

45

500 1000 1500 2000 2500 3000 3500

5

10

15

Graphite

10841186

1399 1729 GO

% A

bsor

banc

e

Wavenumber (cm-1)

1632

Polyaniline-Graphite oxide hybrid – In-situ polymerization of aniline in the presence of synthesized graphite oxide


2 nm

SEM image AFM imageTEM image

2 nm


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


TEM image

SEM images

HRTEM image

500 nm

Polyaniline

5 µm

P1G2

AFM image

3.2 nm 1 nm


Sample

name

β cm

GW-1

Isat GW

cm-2

Polyaniline 5.8 2.5

GO 5.5 3.5

P4G1 8 1.5

P2G1 11 0.7

P1G1 13 0.6

P1G2 19 0.4

Nonlinear optical properties


Polyaniline-phenylene diamine functionalized reduced graphene oxide hybrids

Synthesis of phenylene diamine modified reduced graphene oxide (GONH2)


TEM imageSEM image

5 µm


Synthesis of polyaniline-phenylene diamine modified reduced graphene oxide hybrid

GONH2 to aniline ratio 1:21:12:1


TEM images

SEM image


Remyamol T, Pramod Gopinath, Honey John. Synthesis and nonlinear optical properties of reduced graphene oxide covalently functionalised with polyaniline. Carbon 59 (2013) 308-314.

Sample nameβ

cm GW-1

Isat

GW cm-2

Polyaniline 5.8 2.5

GONH2 4.8 3.7

P2NH2G1 12 0.6

P1NH2G1 15 0.5

P1NH2G2 25 0.2


Synthesis of polyaniline-reduced graphene oxide hybrid

Covalently grafted polyaniline- reduced graphene oxide hybrid


SEM image

TEM image


Open aperture Z-scan plots Optical limiting plots

Sample name β cm

GW-1

Isat GW

cm-2

GO 5.5 3.5

Polyaniline 9.5 2

Polyanilne-g-rGO 20 0.25

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.


Reduced Graphene oxide-ZnO Hybrid

Reduced graphene oxide –ZnO hybrid is synthesized by two routes:

Hydrothermal Synthesis

Solution precipitation technique


Reduced Graphene oxide-ZnO Hybrid

Zn(Ac)2 (1 mmol)

CH3COOHPolyvinylpyrrolidone

(PVP) (0.05 %)

Zn(Ac)2- PVP complex

NaOH

Kept in autoclave at different temperature for

7 h @ 100oC(hydrothermal method)

H-rGO-ZnO-x

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


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 ZnO nanoparticles

IR and Raman spectra of H-rGO-ZnO and S-rGO-ZnO


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


Lot of scope for further work in Hybrids as the optical limiting properties can be enhanced by suitably modifying the functionalities

Conclusion


Collaborators:

1. Dr. Honey John, Department of Chemistry, IIST2. Dr. Reji Philip, Raman Research Institute

Research Students:

1. Ms. Remyamol T2. Ms. Kavitha M K

A word of Gratitude……

hybrids with graphene for optical limiting applications

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