Photo-physical and lasing characterisation of a polyparaphenylenevinylene (PPV) neat film

Abstract

The wave-guided travelling-wave laser action (amplified spontaneous emission) of a neat film of poly(p-phenylenevinylene) (PPV) on a quartz glass substrate prepared by a sulfinyl precursor technique is studied. The samples are transversally pumped with picosecond excitation pulses (wavelength 347.15 nm, duration 35 ps). Lasing occurs at 550 nm. The optical constants of the neat films are determined by transmittance measurements exploiting the multiple beam interference in the transparency region. A fluorescence spectroscopic characterisation is carried out determining the fluorescence quantum distribution, fluorescence quantum yield, degree of fluorescence polarisation, and fluorescence lifetime. The emitting chromophore size (emitting singlet exciton extension) is determined by the ratio of exciton radiative lifetime to repeat-unit based radiative lifetime. The obtained size of about two repeat units is discussed in a disordered solid-state polymer model.

Alternating 2,7- and 3,6-linked carbazole copolymers as wide band gap energy transfer donors

“…Measurements of the fluorescence quantum yields were also undertaken in the solid state using an integrating sphere and were found to be (0.13 ± 0.013) for polymer P1. Clearly the solid-state quantum efficiencies that we deduce are lower than those determined in solution, however, these values are comparable to those described in the literature for films of poly(p-phenylenevinylene) derivatives which have solid-state quantum efficiencies around 0.15 [26].…”

Laser spectroscopic investigation of a new precursor-type polyparaphenylenevinylene

“…Film thickness was 190 nm, and the exposed film area was 5 mm  0:13 mm: Full acceptance angle of emitted laser light was 341. Circles represent measured points and the curve is a fit to the experimental results [26]. The threshold pump pulse energy density w L;th % 100 mJ cm À2 for travelling-wave laser action is marked (identified by kink in Fig.…”

“…Below w L;th the edge emission is caused by spontaneous emission. At high pump pulse energy density the edge emission saturates towards W em;max % 2:8 nJ: This saturation is thought to be caused by singlet-exciton-singletexciton annihilation [26,29] since the distance between two excited chromophores becomes small (two excited chromophores transfer energy bringing one chromophore to the ground-state and the other to a higher-excited singlet state, from where it relaxes non-radiatively with subpicosecond time-constant normally to the first excited singlet state). …”

“…Transmission and refractive index spectrum of a neat PPV film on fused silica substrate[26] (Film thickness 190 nm).…”

“…Repeat-unit based absorption cross-section spectrum and stimulated emission cross-section spectrum[26].…”