Geometry-dependent electronic properties of highly fluorescent conjugated molecules

We present a combined experimental/theoretical study of the electronic prop erties of conjugated para-phenylene type molecules under high pressure up t o 80 kbar. Pressure is used as a tool to vary the molecular geometry and in termolecular interaction. The influence of the latter two on singlet and tr iplet excitons as well as polarons is monitored via optical spectroscopy. W e have performed bond structure calculations for the planar poly(para-pheny lene) and calculated the dielectric function. By varying the intermolecular distances and the length of the polymer repeat unit the observed pressure effects can be explained.