INFLUENCE OF SINGLE-WALL CARBON NANOTUBE LENGTH ON THE OPTICAL AND CONDUCTIVITY PROPERTIES OF THIN ‘BUCKYPAPER’ FILMS

 

Daneesh Simien, Jeff Fagan, Jack F. Douglas, Kalman Migler and Jan Obrzut

 

Polymers Division, National Institute of Standards and Technology,

Gaithersburg, Maryland 20899, U.S.A.

 

ABSTRACT

 

Thin layers of length-sorted single wall carbon nanotubes (SWNT) were formed in to a “buckypaper” sample through vacuum filtration. These length sorted samples exhibit sharp changes in their optical and conductivity (s) properties with increasing SWNT surface coverage. At given surface concentrations, longer nanotubes are found to be more transparent and conducting. Changes of s with SWNT concentration can be quantitatively described by the generalized effective medium (GEM) theory which incorporates both effective medium and percolation theory concepts. The scaling exponents describing the conductivity percolation transition from an insulating to conducting state with increasing concentration are consistent with two-dimensional percolation theory, provided that the SWNTs are sufficiently long. The conductivity percolation threshold, xc, varies with particle aspect ratio L as, xc ~ 1 / L, which also accords with the expectations of conductivity percolation theory. Our results provide a framework for engineering the properties of thin SWNT layers for the numerous technological applications that are envisioned for buckypaper including its effects on photoconductivity.

 

 

 

Presenter: Daneesh Simien

Advisor: Jan Obrzut

 

Polymers Division, Materials Science and Engineering Laboratory,

Bldg 224, Mail Stop 8542

Gaithersburg, Maryland 20899, U.S.A.

 

Tel: 301-975-6895

Fax: 301-975-4924

E-mail: dsimien@nist.gov

 

Sigma xi: non member

 

Poster: “INFLUENCE OF SINGLE-WALL CARBON NANOTUBE LENGTH ON THE OPTICAL AND CONDUCTIVITY PROPERTIES OF THIN ‘BUCKYPAPER’ FILMS “

 

 

Category: Materials