<title>Optoelectronic devices made from multilayer and molecularly doped organic layers</title>

Abstract

We discuss the photovoltaic and electroluminescence properties of three groups of optoelectronic devices with the following organic materials: (A) single layer devices made of para-hexaphenyl (PHP), pristine methyl-substituted laddertype poly-para-phenylene (mLPPP) and N-(2,6- Diisopropylphenyl)-N'-octylterrylene-3,4,11,12-tetracarboxdiimide- (DOTer) sandwiched between ITO and Al electrodes, (B) mLPPP blended with TiO-phthalocyanine (TiO-Pc) and an aromatic macromolecule, (C) multilayer devices consisting of differently arranged layers made of mLPPP, PHP and DOTer. The motivation for these experiments is the optimization of either charge transfer or energy transfer from one molecular to its neighbor molecule. In order to obtain high photocurrents for photovoltaic applications it is favorable to use a combination of a polymer with electron donor properties and an organic substance with high electron affinity, which provides efficient charge transfer resolution in the creation of polarons. In particular we investigated the influence of the location of the photoactive region on the shape and magnitude of the photocurrent action spectra by performing experiments under electrical and optical bias for different excitation conditions. The best photovoltaic yields were obtained for hetero-structure devices.