Enhanced device performance using different carbon nanotube types in polymer photovoltaic devices

The effects of incorporating different types of carbon nanotubes (single-walled, SWCNT; double-walled, DWCNT; and multi-walled carbon nanotubes, MWCNT) in organic solar cells were studied. Different compositions of carbon nanotubes in poly(3-hexiltiophene) (P3HT) were investigated. Absorption spectroscopy, photoluminescence and current–voltage measurements using 10 mW/cm2 white light illumination in air, were carried out to determine the photovoltaic behaviour of the organic solar cells prepared. The addition of carbon nanotubes (CNTs) to the polymer increases the power conversion efficiency by three orders of magnitude compared with the device without CNTs, but there is no clear connection with the number of walls or diameter of the nanotubes. A critical concentration value of 5 wt.% of CNT is found to achieve the highest open-circuit voltage and the best performance for the majority of the CNTs studied.