The Photoluminescence of Ph-LPPP Polymer Under Hydrostatic Pressure

The photoluminescence (PL) spectra of blue light emitted ladder type organic conjugated polymer (ladder-type poly para-phenylene) with trace concentrations of metallic impurities both in the form of thin film and powder at various pressures are measured. We find that the peak 00 in the PL spectrum of Ph-LPPP in the powder form is weaker than that of in film. A red shift and broadening of PL spectra with increasing of pressure in both forms are also observed. However, the shift rates in thin film and in powder are slightly different, which indicates the effect of aggregation on the PL of polymers. The effective conjugated length change of polymer under the pressure is discussed. By this investigation, we conclude that the structure, therefore, the interaction between chains of the polymer plays an important role in its PL spectrum.