Jm. Leng et al., PICOSECOND TO MILLISECOND PHOTOEXCITATIONS IN POLY(PHENYLENE ACETYLENE), Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 256, 1994, pp. 697-703
Using ps transient and cw photoinduced absorption and photoluminescenc
e, and their respective versions of optically detected magnetic resona
nce, we elucidate the origin of photoexcitations in thin films of poly
(phenylene acetylene) (PPA). We clearly identified two kinds of photoe
xcited singlet excitons: the first type is radiative and unrelaxed whe
reas the second type is nonradiative, self trapped and thus long-lived
. Other photoexcitations such as triplets and polarons play only a min
or role in PPA.