PICOSECOND-SPECTROSCOPY AND HYPERLINEAR PHOTOLUMINESCENCE IN POLY(PARA-PHENYLENE)-TYPE LADDER POLYMER

The temporal decay and the spectral evolution of the photoluminescence of poly(para-phenylene)-type ladderpolymer films are studied by tempe rature dependent (20K-300K) streak camera measurements. The luminescen ce spectrum originating from two different emitting species is compose d of a broadband yellowish contribution of extrinsic nature (lambda(em )=600nm) and a spectrally sharp component in the blue-green region. On increasing the illumination to high intensities the luminescence of t his latter intrinsic component (lambda(em)=492nm) is increased dramati cally as a change from linear to hyperlinear behaviour is observed. Th e material is found to be photochemically stable and the luminescence is not limited by saturation effects even under high excitation condit ions, which is essential for laser application.