Photoinduced absorption and excitation spectra studies of excited states in a cyano-derivative of poly (p-phenylenevinylene)

We have identified in a cyano-substituted derivative of poly (p-phenylenevinylene) a broad photoinduced absorption signal at 1.3 eV from a photoexcited state with a lifetime of 0.2 ms at 20 K, which we assign to the triplet exciton. We present here excitation spectra in the range 2–5 eV of the triplet-triplet photoinduced absorption, and photoluminescence signals, which are both broadly flat above the onset of the linear absorption. From these results we conclude that quantum efficiencies of singlet and triplet exciton generation are constant over the excitation range.