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1 December 1997 Long-lived polarons and triplet excitons in ladder-type poly(p-phenylenes) and poly(p-phenylene ethynylenes)
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Recent x-band optically detected magnetic resonance studies of spin 1/2 polaron and spin 1 triplet exciton dynamics in ladder-type poly(p-phenylene) and poly(p-phenylene ethynylene) (PPE) films and solutions are described. The results suggest that the polaron resonance is due to interchain polaron pairs with lifetimes 10 microsecond(s) <EQ (tau) <EQ 4 ms range. The absence of delayed fluorescence at such times as well as other observations lead to the conclusion that the mechanism responsible for this resonance is the nonradiative quenching of singlet excitons by the polarons, whose population decreases at the field-for- resonance. The full-field triplet pattern is 700 - 1200 G wide, consistent with a triplet localized on a phenylene ring. In frozen toluene solutions of PPE, the amplitudes (Delta) I/I of both the polaron and half-field triplet resonances decrease similarly with concentration, and increase similarly with laser power P as P(alpha ), where 1/3 <EQ (alpha) <EQ 1/2. Hence, the triplet resonance is believed to be due to triplet intrinsically trapped and stabilized at similar interchain sites. Possible scenarios which link the processes yielding the resonances are also discussed.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jonathan Partee, Joseph Shinar, Wilhelm Graupner, Guenther Leising, Scott W. Jessen, Arthur J. Epstein, Yi Wei Ding, and Thomas J. Barton "Long-lived polarons and triplet excitons in ladder-type poly(p-phenylenes) and poly(p-phenylene ethynylenes)", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997);

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