Penta(organo)[60]fullerenes as acceptors for organic photovoltaic cells

Pentaaryl[60]fullerene derivatives, C-60(C6H4Ph)(5)Me, C-60(C6H4OPh)(5)Me, C-60((C6H4Bu)-Bu-n)(5)Me, Fe[C-60((C6H4Bu)-Bu-n)(5)]Cp, and Ru[C-60((C6H4Bu)-Bu-n)(5)]Cp have been used as acceptor materials in bulk heterojunction-type organic photovoltaic cells in combination with poly(3-hexylthiophene) as a donor material. High open-circuit voltages (up to 0.76 V) were obtained, which are attributed to the high LUMO of the penta(organo)[60]fullerenes. Scanning electron microscopic analyses of the cross-section of the devices indicated a homogeneous distribution of the donor and the acceptor compounds, which accounts for the moderate short-circuit current and photocurrent conversion efficiency (eta = 1.08).