Organic polymer-based bulk heterojunction solar cells have been intensively developed during the last decade. Historically, conjugated polymers of the PPV (para-phenylene vinylene) family such as poly (2-[(3'-7'-dimethyloctyl)oxy]-5-methoxy-1,4-phenylene}-1,2-ethenediyl) (MDMO-PPV) and poly ({[(2ethylhexyl)oxy]-5-methoxy-1,4-phenylene}-1,2-ethenediyl) (MEH-PPV) were among the very fi rst electron-donor materials utilized for the construction of plastic solar cells. Power-conversion effi ciencies up to 2.5-3.0% have been obtained for solar cells based on the blends of fullerene derivatives [6,6]-phenyl-C 61 -butyric acid methyl ester ([60]PCBM) and [6,6]-phenyl-C 71butyric acid methyl ester ([70]PCBM), and MDMO-PPV. [ 1 , 2 ] Poly(3-alkylthiophenes) (P3ATs) formed the next generation of electron-donor polymers and were shown to be more promising compared with PPVs. [ 3 ] Bulk-heterojunction solar cells based on composites of poly(3-hexylthiophene) (P3HT) with [60]PCBM have demonstrated reproducible power-conversion effi ciencies of 3.5-4.5%. [ 4 , 5 ] The P3HT/PCBM composite system has been a "running horse" in organic photovoltaics for many years. [ 6 ] The emergence of third-generation electron-donor copolymers has led to signifi cant progress in organic photovoltaics. [ 7 , 8 ] Polymer-based solar cells with effi ciencies of 5-7% have been reported recently by many research groups worldwide. [9][10][11] Record performances were achieved using so-called "push-pull" polymers comprising different electron-defi cient heterocyclic blocks such as quinoxaline [ 12 ] benzothiadiazole, [ 13 ] 1,4-diketopyrrolopyrrole, [ 14 ] thieno [3,4-b]thiophene, [ 15 ] thieno [3,4-c]pyrrole-4,6-dione, [ 16 , 17 ] and isoindigo [ 17 ] in combination with electron-rich thiophene units or thiophene-based heterocycles such as cyclopentadithiophene, [ 18 ] dithienobenzene, [ 19 ] or dithienosilole. [ 20 ] These examples give the impression that the presence of both electron-defi cient heterocycles and electron-donating thiophene rings in the polymer structure is an essential requirement for achieving a high photovoltaic performance [7][8][9][10][11] This communication features an alternative type of conjugated polymer that can produce competitive photovoltaic characteristics compared with modern "push-pull" polymer systems. The investigated polymer, AnE-PV stat stat ( Figure 1 ), is distinguished by its PPV-type molecular structure, the absence of any heterocyclic units, particularly thiophene rings, and the presence of an anthracene unit bearing two adjacent triple bonds. Another peculiarity of this polymer is the statistical distribution of n-octyloxy-and 2-ethylhexyloxysolubilizing side chains along the polymer backbone. [ 21 ] Solar cells based on the polymer AnE-PV stat stat and the conventional fullerene-based material [60]PCBM showed rather modest power-conversion effi ciencies of 2.0-3.0% under our experimental conditions. However, the photovoltaic performance of AnE-PV stat stat was improved signifi cantly to the level of ...

We report the synthesis and investigation of four novel pyrrolidinofullerenes bearing electron donating alkoxyphenyl substituents. Cyclic voltammetry studies revealed that the designed fullerene derivatives have reduced electron affinity compared to the conventional material [60]PCBM. The organic bulk heterojunction solar cells based on the pyrrolidinofullerenes and P3HT revealed impressive open-circuit voltages of 700-780 mV and enhanced light power conversion efficiencies with respect to the reference PCBM/P3HT devices. The designed materials demonstrated also reasonably good compatibility and decent photovoltaic performances in combination with the carbazole-thiophenebenzothiadiazole copolymer PCDTBT.

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