Improvement of characteristics on polymer photovoltaic cells composed of conducting polymer - fullerene systems

Photovoltaic properties of the cells consisting of a heterojunction of conducting polymer-fullerene systems and a semiconductor oxide thin film, which is transparent in the visible-wavelength range, have been investigated. Introducing the transparent semiconductor oxide, such as zinc oxide (ZnO), into the photovoltaic cells with conducting polymer - fullerene systems, high performance has been obtained. Especially in the layered photovoltaic cells with the structure of ITO/ZnO/C60/PAT6/Au, the high monochromatic energy conversion efficiency and the external quantum efficiency have been realized. The photovoltaic properties have been interpreted by the effective absorption of incident photons around the interface of conducting polymer and fullerene, the interpenetrated fullerene/conducting polymer interface involving the efficient photo-induced charge transfer, and the short distance between the electron-generation region and electrode, resulting in the enhancement of the electron collection to the electrode.