2.5% efficient organic plastic solar cells

We show that the power conversion efficiency of organic photovoltaic devices based on a conjugated polymer/methanofullerene blend is dramatically affected by molecular morphology. By structuring the blend to be a more intimate mixture that contains less phase segregation of methanofullerenes, and simultaneously increasing the degree of interactions between conjugated polymer chains, we have fabricated a device with a power conversion efficiency of 2.5% under AM1.5 illumination. This is a nearly threefold enhancement over previously reported values for such a device, and it approaches what is needed for the practical use of these devices for harvesting energy from sunlight.

The interconnection between efficiency and morphology of two component systems in plastic solar cells

Using the ultrafast photoinduced electron transfer with long-living charge separation in the conjugated polymer/fullerene thin films, photovoltaic devices have been fabricated. The photoinduced charge separation happens with internal quantum efficiency near unity. The performance of such "bulk heterojunction" photovoltaic devices is critically dependent on the transport properties of the interpenetrating network. The influence of the variation of different donor / acceptor materials on the sample morphology is monitored by atomic force microscopy (AFM), while I/V characteristics have been studied to evaluate the conversion efficiency

Investigation of photoinduced charge transfer in composites of a novel precursor PPV polymer and fullerenes

Homogenous blends of a functionalized methanofullerene, the [6,6]-Phenyl C61-butyric acid methyl ester (PCBM), with poly (p-phenylene vinylene) (PPV) made from a novel non-ionic precursor route were investigated by optical spectroscopy and by photocurrent measurements. The conversion process of the precursor polymer to the PPV in the blends with PCBM was monitored by IR absorption. In composites of PPV/PCBM strong quenching of the PPV luminescence was observed. LESR (light induced electron spin resonance) and PIA (photoinduced absorption) studies confirmed the occurrence of photoinduced electron transfer from the PPV to PCBM. Photovoltaic devices made from PPV/PCBM blends showed monochromatic power conversion efficiencies of app. 0.3%. The spectral photocurrent was observed to follow the absorption profile of the PPV

Towards increasing the photon harvesting in bulk heterojunction polymer solar cells.:Electrochemical, Radiational, and Thermal Energy Technology

Org. solar cells based on interpenetrating networks of conjugated polymer donors and fullerene-based acceptors with MA 1.5 efficiencies up to 3% were presented recently. For further improvement of the efficiency, the absorption of the solar light should be increased. This can be done by matching the active layer absorption better to the terrestrial solar emission spectrum and by increasing the absorption coeff. In this contribution the authors present a combined spectroscopic and device study of novel materials that extend the absorption to the red. The systems studied are, among others, low bandgap polymers as electron donors or dye sensitized fullerene compds. The photophys. properties are studied by excited state spectroscopy and the materials are discussed with regard to their suitability for efficient photoinduced charge generation. The photovoltaic activity is demonstrated by photocurrent action spectra as well as by AM 1.5 efficiencies of prototype devices made using these novel materials. [on SciFinder(R)