Photogeneration and Photoluminescence Studies in Bilayer Structures Containing Poly(P-Phenylene Vinylene) and Molecularly Doped Polymers

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Abstract
The photogeneration efficiency for photocarriers (holes and electrons) in poly(p-phenylene vinylene) (PPV) is measured in the presence of high electric fields, for bilayer sandwich devices containing molecularly doped polymers (MDP) and PPV. A hole transport diamine molecule (TPD) and an electron transport malononitrile molecule (BCFM) each dispersed in polycarbonate were used to study holes and electrons respectively. By performing photoluminescence (PL) experiments in the bilayer structures and hole collection experiments in single layers without the TPD:PC overcoat, we have concluded that generation of photocarriers in PPV is mainly a bulk mediated process, assisted by the applied electric field, and not sensitized by the presence of the MDP. The electric field dependence of photogeneration suggests that photoexcitation results in a strongly correlated electron-hole pair dissociated by the electric field.