State-of-the-art MDMO-PPV: PCBM bulk hetero-junction organic solar cells: materials, nano-morphology and electro-optical properties.

Abstract

Current state-of-the-art bulk hetero-junction organic photovoltaic devices will be discussed based on poly(2-methoxy-5-(3',7'-dimethyl-octyloxy))-p-phenylene vinylene, (MDMO-PPV), as an electron donor and (6,6)-phenyl-C-61-butyric-acid (PCBM) (a soluble C60 derivative) as electron acceptor. A brief review will be provided summarizing recent results on efficiency enhancement and on morphological investigations. A significant increase in power conversion efficiency has been demonstrated for devices based on so-called 'sulphinyl' synthesised MDMO-PPV (eta(AM1.5) = 2.9%) in comparison with devices based on 'Gilch' synthesised MDMO-PPV (eta(AM1.5) = 2.5%). In order to understand the higher efficiency values obtained using a different solvent or a different MDMO-PPV-material, electrical and morphological investigations are being performed. Concerning the latter, it has been shown with various analytical techniques that the morphology of the blended photoactive films and also the power conversion efficiency of the corresponding photovoltaic devices are both simultaneously influenced by preparation conditions such as choice of the solvent and drying conditions.