Intramolecular donor–acceptor copolymers containing side‐chain‐tethered perylenebis(dicarboximide) moieties for panchromatic solar cells

A series of side‐chain‐tethered copolymers containing the N‐(2‐ethylhexyl)‐N′‐(thiophene‐3‐yl)‐3,4:9,10‐perylenebis(dicarboximide) (thiophene‐PDI) moieties and 4,4‐diethylhexyl‐cyclopenta[2,1‐b:3,4‐b′]dithiophene unit were synthesized via Grignard metathesis polymerizations. With the incorporation of pendent perylenebis(dicarboximide) (PDI) moieties as acceptor side chains and thiophene as the donor backbone, the copolymers exhibited the intramolecular donor–acceptor characteristic and displayed a panchromatic absorption ranging from 290 to 1100 nm and ideal bandgaps of 1.49 to 1.52 eV. Due to the coplanarity of PDI moieties, the charge separation and transfer process were more effective and enhanced after photoexcitation. When increased the weight ratio of PC₆₁BM:polymer to 3, the J_sc could be raised significantly. The value of bandgap decreased slightly, and both V_oc and J_sc showed an upward trend with the increase of molar ratio of thiophene‐PDI unit from 50% (the copolymer P11) to 75% (the copolymer P13). The polymer/PC₆₁BM devices have shown a significant improvement from 0.45 to 1.66% with a judicious modulation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1978–1988