Novel 1,3-Diketone Modified Fullerenes for Organic Photovoltaic Cells

The feasibility of novel 1,3-diketone modified C₆₀s (compound 1 and 2) was studied as acceptor materials in organic photovoltaic cells (OPVC). 1,3-Diketone modified fullerenes were synthesized by the addition reaction of 1,3-bis(5′-hexylthiophen-2′-yl)propane-1,3-dione with C₆₀ in the presence of DBU (1,8-diazabicyclo[5,4,0]undec-7-ene). From this procedure two products can be prepared, which are mono- (1) and di-substituted compound (2) in the yield of 40% and 17%, respectively. OPVCs fabricated by using the mixture of P3HT and compound 1 as an active layer showed excellent power conversion efficiency of about 3.42% after annealed at 160 °C for 15 min and we believe that substantial improvements can be realized by nano-structured heterojunction. It was demonstrated that 1,3-diketone modified C₆₀ (compound 1) was one of the promising candidates for acceptor materials for OPVCs.