Electronic interaction between photoexcited poly(p-phenylene vinylene) and carbon nanotubes

We have studied the electronic interaction between photoexcited poly(p-phenylene vinylene) (PPV) and multiwall carbon nanotubes (MWNT's) using photoluminescence (PL) and photoinduced absorption (PIA) spectroscopy. We have found that the MWNT's strongly interact with the photoexcited PPV, while there is no significant interaction in the ground state. The pi conjugation of PPV was slightly reduced in the composite, reflecting the nanoscopic structural influence of the MWNT's. On the basis of its temperature and frequency dependence, the PIA spectrum was found to originate from the same species as the pure PPV film, namely, triplet excitons formed in PPV via intersystem crossing. We have concluded that the predominant electronic interaction is the nonradiative energy transfer of singlet excitons from the PPV to the MWNT's.