Search

Abstract--An improved and simplified synthetic method for 4-bromo-2,2'-bipyridine (5) has opened a way to the synthesis of the model compounds 8a, b of polymer 9. 8a, b confirmed the effective conjugation segment of polymer 9 to consist of an alternation of three aryl and two ethynyl units (Ar--C Is equivalent to C--Ar--C Is equivalent to C--Ar) due to the zig-zag structure of the polymer. It was found to be the smallest conjugated unit necessary to obtain excellent fluorescence. [ABSTRACT FROM AUTHOR]

Novel 2,2′-bipyridine-based conjugated polymers of formula 2 have been synthesized by Pd-catalyzed cross-coupling reactions between 4,4′-dibromo-2,2′-bipyridine (3) and substituted phenyldiacetylenes (4). The zig-zag arrangement of the 2,2′-bipyridine units implies a helical conformation of 2. The solubility of 2 requires at least a dodecyl side-chain. 2 is thermostable up to 400°C. The polymers have a high fluorescence quantum yield in solution (60%). [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effect of solvent on the photovoltaic performance of bulk heterojunction organic solar cells comprising of an n type polymer poly (2,5-didodecyloxy-1,4-phenylene-2-cyanovinylene-2,5-dioctyloxy-1,4-phenylene-1-cyanovinylene) (DE119) and poly(3-hexylthiophene) (P3HT). We have fabricated devices from blends of P3HT and DE119 with varying acceptor ratio cast from chlorobenzene, toluene and chloroform. For the devices with 1:2wt ratio of P3HT and DE119, respectively, cast from chlorobenzene, we achieved a short circuit current density of (J SC) of 0.85mA/cm2 and an open circuit voltage (V OC) of 1100mV with a FF of 0.33 leading to an efficiency of 0.3%. We also showed that inversion of the device can be accomplished using an amorphous titanium oxide (TiO x ) as the hole blocking layer. [Copyright &y& Elsevier]