Measurements are reported of the time-resolved photoluminescence (PL)
from unoriented films of poly(p-phenylenevinylene) [PPV], methoxy,5-(2
'-ethyl-hexyloxy)-p-phenylenevinylene] [MEH-PPV] and a cyano-substitut
ed derivative of PPV, CN-PPV. The PL features observed for PPV and MEH
-PPV are consistent with the ultrafast formation and subsequent energy
migration of intrachain excitons followed by their decay through radi
ative and non-radiative processes. The dynamics of the PL in CN-PPV is
substantially altered compared to that of PPV and MEH-PPV films and a
lso to that of CN-PPV in solution. A transient high energy feature is
observed that is not seen in continuous-wave (CW) measurements and a l
ong-lived low energy feature which corresponds to the CW PL. These res
ults are consistent with the formation of inter-chain excitations in C
N-PPV films.