Title: Study of photoluminescence quenching and DC conductivity measurements in polymer-SWNT composite films for various SWNT concentrations

Authors: Inderpreet Singh, P.C. Mathur, P.K. Bhatnagar, Inderpreet Kaur, L.M. Bharadwaj, Ravindra Pandey

Addresses: Materials Laboratory, Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. ' Materials Laboratory, Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. ' Materials Laboratory, Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India. ' Biomolecular Electronics Nanotechnology Division, Central Scientific Instruments Organization, Sector-30, Chandigarh, India. ' Biomolecular Electronics Nanotechnology Division, Central Scientific Instruments Organization, Sector-30, Chandigarh, India. ' Department of Physics, Michigan Technological University, 1400 Townsend Dr. Houghton, MI49931, USA

Abstract: Conducting polymer-SWNT composite films have a high potential in the area of photovoltaic devices and light emitting diodes (LEDs). SWNTs have high electron affinity and high mobility for electrons. As a result of this, the separation of photoinduced charges in the solar cell is very fast and efficient. For LEDs, the polymer-SWNT composite films act as efficient electron transporting layer (ETL). In the present work, composite solutions of P3HT and SWNTs were prepared in 1,2-dichlorobenzene with nanotube to polymer mass ratios varied from 0% to 30%. The films from this solution were spin coated on a glass substrate with the help of spinner keeping the film thickness ∼100 nm. The photoluminescence (PL) of the film was observed with the help of Shimadzu Spectrofluorophotometer. It was found that the PL intensity decreases by ∼90% as the concentration of the SWNT is increased from 0% to 30%. This decrease is due to the transfer of electrons from P3HT to SWNTs before the exciton in the polymer can decay radiatively to emit PL. DC conductivity of the composite films was measured with the help of Keithley sourcemeter in sandwich structures. It was found that conductivity increases by more than five orders of magnitude with the increase of SWNT concentration. The composite films can therefore act as good electron transporter for LEDs and efficient electron acceptor for solar cells.

Keywords: SWNT; conducting polymers; composite films; solar cells; photoluminescence quenching; DC conductivity; percolation limit; photovoltaics; LED; nanotechnology; nanocomposites; single-walled nanotubes; carbon nanotubes; light emitting diodes; nanoelectronics.

DOI: 10.1504/IJNT.2009.025312

International Journal of Nanotechnology, 2009 Vol.6 No.7/8, pp.745 - 752

Published online: 18 May 2009 *

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