Aggregate versus Excimer Emissions from Poly(2,5-di-n-octyloxy-1,4-phenylenevinylene)

Using fractions of poly(2,5-di-n-octyloxy-1,4-phenylenevinylene) (DO−PPV) of different chain lengths, the interchain interactions in both the solution and the bulk states from ambient to cryogenic temperatures were examined via a combination of steady-state and time-resolved photoluminescence spectroscopic techniques. Results indicated that the emission from these aggregates bears characteristics of quantum mechanical dimerization, not that of the extended conjugation of single chains. The emission spectrum from films is generally consistent with the “aggregate emission” spectrum extracted from aggregated solutions; nevertheless, there indeed exists minor emission at the red end of the spectrum, representing contribution from excimers.