PHOTOLUMINESCENCE AND UV-VIS ABSORPTION STUDY OF POLY(PARA-PHENYLENE)-TYPE LADDER-POLYMERS

Soluble poly(para-phenylene) (PPP)-type ladder-polymers have been show n to be suitable as active layers in light emitting diodes (LEDs). In this work we discuss the absorption spectra in the ultraviolet (UV) an d visible (VIS) range as well as photoluminescence spectra of such mat erials. The steepness of the band edge in the absorption spectra indic ates that high intrachain order and well-defined conjugation length ar e characteristic for these ladder-type PPPs (LPPP). By investigating t he absorption and photoluminescence of LPPP dissolved in toluene and o f solid LPPP films we study the influence of molecular interaction (fo rmation of excimers, luminescence quenching through the presence of ne ighbouring molecules within the distance of energy transfer) on the ph otoluminescence quantum yield.