Luminescence efficiency and time dependence in a high electron affinity conjugated polymer

We report measurements of the efficiency and time dependence of photoluminescence in a high electron affinity cyano-substituted derivative of poly (p-phenylenevinylene). In solution the photoluminescence quantum yield is 0.52 +/- 0.05, and the luminescence lifetime is 0.9 +/- 0.1 ns. In solid films the luminescence quantum yield is 0.35 +/- 0.03 and the luminescence lifetime, of 5.6 +/- 0.2 ns, is much longer. These results strongly suggest that the emission from the film is from an inter-chain excitation, and that inter-molecular interactions are an important factor to consider in the design of highly luminescent conjugated polymers.