Delayed luminescence of the ladder-type methyl-poly(para-phenylene) Original Research Article

The delayed luminescence of a film of ladder-type π-conjugated polymer – the methyl-substituted poly(para-phenylene) (MeLPPP) – has been detected and investigated at 6, 77 and 295 K. The delayed emission consists of a delayed fluorescence (DF) in the region of 450–550 nm, which decreases by a factor of 10 during 200 ns (at 77 K), and a phosphorescence in the region of 600–750 nm with a much slower decay rate. The latter decreases by a factor of 10 during about 100 μs. The DF spectrum is the superposition of the intrinsic fluorescence emission and an excimer-type emission. The analysis of the experimental data provides evidence for a geminate pair recombination being the origin of both types of DF.