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Summary: (derivative-like) and 2.7 eV (absorption band),
which are similar to those in disordered films
(14), the RR P3HT EA spectrum also contains
strong oscillation with zero crossing at 2.75 eV
(Fig. 4). Such oscillation was previously seen in
-sexithienyl microcrystallites and analyzed in
terms of a charge-transfer exciton near the con-
tinuum level (29). This may be a prerequisite
for the formation of Franz-Keldysh band-edge
oscillation, such as in EA of single-crystal poly-
diacetylene (30). We also found that this oscil-
lation gradually disappears upon aging of the
film, due to reduced electron coherence caused
by the oxygen attack on the polymer chains
(Fig. 4).
In conclusion, we studied and compared
long-lived photoexcitations in RR and RRa
P3AT films. In RR P3AT films, where lamellae
are formed, the increased interplane interchain
interaction, t delocalizes the traditional 1D
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