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

The delayed luminescence of a film of ladder-type pi-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 mu s. 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. (C) 1999 Elsevier Science B.V. All rights reserved.