Polymer photovoltaic devices using fully regioregular poly[(2-methoxy-5-(3′,7′-dimethyloctyloxy))-1,4-phenylenevinylene]

Fully regioregular poly[(2-methoxy-5-(3',7'-dimethyloctyloxy))-1,4-phenylenevinylene]s (MDMO-PPVs) synthesized by the Horner route were utilized for polymer photovoltaic devices, and their performance was compared with that of regiorandom MDMO-PPVs. The mixture films of the regioregular MDMO-PPVs and 1-[3-(methoxycarbonyl)propyl]-1-phenyl-(6,6)-C-61 (PCBM) were successfully fabricated by spin coating using a hot chlorobenzene solution. Significant improvements in fill factor (FF) and short circuit current (I-SC) were observed for the devices with regioregular MDMO-PPV compared with those for devices with regiorandom MDMO-PPV. A power conversion efficiency of 3.1% was achieved with regioregular MDMO-PPV under AM1.5 illumination, which is the highest efficiency reported for the PPV:PCBM system so far, whereas a power conversion efficiency of only 1.7% was achieved with regiorandom MDMO-PPV. It is concluded that both higher hole mobility resulting from the higher crystallinity of the polymer and better mixing morphology between the polymer and PCBM in bulk heterojunction films contributed to the improvement in the photovoltaic performance of devices with regioregular MDMO-PPV.