Sterically controlled azomethine ylide cycloaddition polymerization of phenyl-C61-butyric acid methyl ester.

Phenyl-C61-butyric acid methyl ester (PCBM) is polymerized simply using a one-pot reaction to yield soluble, high molecular weight polymers. The sterically controlled azomethine ylide cycloaddition polymerization (SACAP) is demonstrated to be highly adaptable and yields polymers with probable Mn≈ 24 600 g mol(-1) and Mw≈ 73 800 g mol(-1). Products are metal-free and of possible benefit to organic and hybrid photovoltaics and electronics as they form thin films from solution and have raised LUMOs.

One small step in synthesis, a big leap in charge mobility: diphenylethenyl substituted triphenylamines.

Star-shaped charge transporting materials with a triphenylamine core and a varying number of diphenylethenyl sidearms, obtained using a one step synthesis procedure from commercially available and relatively inexpensive starting materials and possessing comparatively high hole drift mobility (up to 0.017 cm(2) V(-1) s(-1)), are reported.

Bimolecular recombination coefficient as a sensitive testing parameter for low-mobility solar-cell materials.

Bimolecular charge carrier recombination has been clarified in bulk-heterojunction solar cells based on a blend of regioregular poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene using the time-of-flight method. We show how bimolecular recombination influences the charge carrier transport, how it limits the efficiency of low-mobility solar cells, and how to estimate the bimolecular recombination coefficient. We found that bimolecular recombination in these efficient photovoltaic materials is orders of magnitude slower as compared to Langevin recombination expected for low-mobility materials.

Extraction current transients: new method of study of charge transport in microcrystalline silicon.

The transport properties of microcrystalline silicon, namely, mobility and conductivity, are investigated by a new method, for which the simple theory as well as numerical modeling is presented. The basic idea of the new method is verified on amorphous hydrogenated silicon by comparison with the widely used time-of-flight method. Contrary to time of flight, the new method can be used even for relatively conductive materials.