optical properties of carbon nanotubes

Andreas Graw

motivation

Schematic sketch of a FET (source: IBM)

Sketch of a display based on CNTs as emitter(source: K. Dean, Nature Photonics 1, 273 - 275 (2007) )

Fluorescence of SWCNT(source: Rice University)

outline

motivation

principles of carbon nanotubes

electronic properties

optical propertiesraman spectroscopyfluorescence

outlook

principles of carbon nanotubes

graphene unit cell(a) in real space (b) first Brillouin zone

Source: M. Engel: Graphene and Carbon Nanotube based optoelectronic devices (2012)

principles of carbon nanotubes

Tight binding modelOnly nearest neighbor interaction

Source: M. Engel: Graphene and Carbon Nanotube based optoelectronic devices (2012)

with empirical parameters ϵ2p and γ0

principles of carbon nanotubes

electronic band structureConduction and valence band touch at six distinct points at the Fermi energy

Source: M. Engel: Graphene and Carbon Nanotube based optoelectronic devices (2012)

E F

electronic properties

electronic band structurequantization of allowed states along and the continuity of states along

Source: Bo Xu: Phonon Scattering and Electron Transport in Single Wall Carbon Nanotube (2013)

principles of carbon nanotubes

electronic band structure

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

optical properties

Raman spectroscopyInelastic scattering of monochromatic lightdue to interaction with molecular vibrations

optical properties

Raman spectroscopystronger Raman signal for resonance with van Hoven singularities

→ information about DOS of CNTs

Source: M. Dresselhaus: Raman Spectroscopy on isolated single wall carbon nanotubes Carbon 40, 2043-2061 (2002)

optical properties

Raman RBM

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

D (nm)=248ωRBM

Source: S. Bachilo: Structure-assigned optical spectra of single walled carbon nanotubes, Science 298 (2002)

optical properties

optical transitionsfluorescence

λ11 (nm) E11 (eV) Helicity (n,m)

952 1.302 (8,3)

1023 1.212 (7,3)

1053 1.177 (10,2)

1122 1.105 (7,6)

1172 1.058 (8,6)

1250 0.992 (10,3)

1323 0.937 (9,7)

1376 0.901 (12,2)

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

optical properties

extinction of bundled SWNT

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

optical properties

fluorescence

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

red shift of fluorescence of approximately 45/cm from absorption spectrum

optical properties

single SW-CNT spectroscopy

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

optical properties

single SW-CNT spectroscopy

Source: H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)

optical properties

length dependence of fluorescence

Source: T. Cherukuri: Length- and Defect-Dependent Fluorescence Efficiencies of Individual Single-Walled Carbon Nanotubes, ASC 6 (2012)

optical properties

coulomb interactions - excitonsdiscrepancy with tight binding model

Source: S. Bachilo: Structure-assigned optical spectra of single walled carbon nanotubes, Science 298 (2002)

optical properties

two photon excitationdirect measurement of excitons → binding energy of ~400meV

Source: F.Wang: The Optical Resonances in Carbon Nanotubes Arise from Excitons, Science 308 (2005)

outlook

Source: http://www.cnt-initiative.de

90 companieswith an annual budget ~100 Mio. €

projects:- electronics- lightweight constructions- energy...

Source: http://www.soci.org

Source: http://www.physorg.com

references

[1] H. Pedrosa: The Optical Properties of Single-walled Carbon Nanotubes (2006)Dissertation, University of Rochester

[2] F. Wang: The Optical Resonances in Carbon Nanotubes Arise from ExcitonsScience 308, 838-841 (2005)

[3] M. Engel: Graphene and Carbon Nanotube based optoelectronic devices (2012)Dissertation, University of Karlsruhe

[4] T. Cherukuri: Length- and Defect-Dependent Fluorescence Efficiencies of Individual Single-Walled Carbon Nanotubes

ACS Nano 6 (1), 843-850 (2012)[5] M. Dresselhaus: Raman Spectroscopy of carbon nanotubes

Physics Reports 409, 47-99 (2005)[6] S. Bachilo: Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes

Science 298, 2361-2366 (2002)[7] M. Dresselhaus: Raman Spectroscopy on isolated single wall carbon nanotubes

Carbon 40, 2043-2061 (2002)[8] Bo Xu: Phonon Scattering and Electron Transport in Single Wall Carbon Nanotube

(2013)

Thank you for your attention!