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 temperature dependent (20K-300K) streak camera measurements. The luminescence spectrum originating from two different emitting species is composed 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 this latter intrinsic component (lambda(em)=492nm) is increased dramatically as a change from linear to hyperlinear behaviour is observed. The material is found to be photochemically stable and the luminescence is not limited by saturation effects even under high excitation conditions, which is essential for laser application.