Excited state inhibition of luminescence in DPOP-PPV

The optical properties of a luminescent polymer, poly[1,4-phenylene-1,2-di( phenoxyphenyl)] vinylene (DPOP-PPV), have been investigated, Measurement of photoluminescence (PL) quantum efficiency shows an unusual increase in eff iciency in the solid state over solution, 52% to 6% respectively. Investiga tions into the stimulated emission properties of this material were carried out but no amplified spontaneous emission was observed. To investigate the presence of excited state absorption features photoinduced absorption (PA) measurements were performed. An extended polaron absorption band, from 1.5 eV to 2.25 eV was observed. This overlaps the emission spectra and therefo re inhibits stimulated emission. This highlights the need to consider the e ffects of excited state absorption on the emission when synthesising new ma terials.