Photovoltaic effect in heterostructure consisting of poly(p-phenylene vinylene) derivative and polypyridine

The characteristics of a photovoltaic device based on a heterostructure con sisting of poly(2-methoxy-5-dodecyloxy-p-phenylene vinylene) (MDOPPV) and p olypyridine (PPy) have been studied. The heterostructure device shows a sig nificant enhancement of the photovoltaic properties compared to the single- layer devices based on MDOPPV or PPy. For example, the device shows a signi ficantly larger photocurrent than a device consisting only of MDOPPV. Moreo ver, notable quenching of the photoluminescence of the two polymers due to lamination has also been observed. These results indicate that a photoinduc ed charge transfer occurs between MDOPPV and PPy. Kowever, the photoinduced charge transfer between these polymers cannot be explained by the bulk ele ctronic energy structure of the polymers estimated from the optical absorpt ion and the atmospheric photoemission spectra. A possible mechanism, which takes modulation of electronic energy structure at the interface due to a l ocal lattice distortion into account, has been proposed. Another possible m echanism of the enhanced carrier generation based on the polarization at th e MDOPPV/PPy interface is also mentioned.