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Abstract
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We investigated the efect of multiwall carbon nanotubes grafted with poly(3-dodecylthiophene) (CNT-graft-PDDT) on the
performance of poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester photovoltaic cells. It is demonstrated
that the presence of small amounts of these modifed CNTs improves the structural organization of the flms as evidenced
by the grazing incidence wide-angle X-ray scattering studies. The ultraviolet–visible (UV–Vis) spectroscopy revealed that
the incorporation of CNT-graft-PDDT changes the absorption intensity and induces a redshift to characteristic peaks. CNT
hybrid features have appeared on the surface morphology as verifed by atomic force microscopic images. The concentration
of additive was optimized at 0.5 wt% to obtain the highest efciency. Doping with this concentration of CNT-graft-PDDT
led to 380% power conversion efciency improvement by enhancement of short-circuit current density (Jsc) from 5.12 to
11.98 mA/cm2, open-circuit voltage (Voc) from 0.6 to 0.66 V, and fll factor from 0.41 to 0.62 in comparison with a reference
cell. The photophysics of hybrid systems were also studied by means of the electrochemical impedance spectroscopy as well
as V
oc and Jsc dependent on the light intensity.
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