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A trilobal non-fullerene electron acceptor, BTT-3PDI , incorporating benzo[1,2- b :3,4- b ′:5,6- b ″]trithiophene (BTT) as the core and three bay-substituted perylenediimides (PDIs) as the arms, was designed and synthetized. It shows a high electron mobility of 3.69 × 10 −3 cm 2 V −1 s −1 because it is a crystalline semiconductor for the partially conjugated structure between PDI units and BTT core. BTT-3PDI shows a matched energy levels and a complementary absorption spectrum with PTB7-Th. The conventional polymer solar cells were fabricated without any processing additive or posttreatment. It showed a power conversion efficiency (PCE) of 1.35% because the unconspicuous microphase separation of the blend film leads to low electron mobility (1.67 × 10 −5 cm 2 V −1 s −1 ) and hole mobility (2.80 × 10 −5 cm 2 V −1 s −1 ). The study provides a proof that the crystalline PDI derivative with small dihedral angles between a core and PDI units can also avoid serious molecular aggregation and large phase separation in the active layer. [ABSTRACT FROM AUTHOR]

Two novel acceptor pended push–pull conjugated polymers PTT–DTBT and PT–DTTBT ，incorporating thieno[3,2– b ] thiophene in the backbone chain and conjugated side chains respectively, were designed and synthesized. The effects of the location of thieno[3,2– b ]thiophene units on the thermal, photophysical, electrochemical and photovoltaic properties of the polymers were investigated. Compared to the polymer PTT–DTBT , the polymer PT–DTTBT with thieno[3,2– b ]thiophene units in the side chains shows more broadened and red–shifted absorption, smaller band gap and higher hole mobility. Bulk heterojunction solar cells with the polymers as electron donors and (6,6)–phenyl–C 61 –butyric acidmethyl ester as the electron acceptor were fabricated, and the PT–DTTBT –based device exhibits a higher power conversion efficiency of 4.07% than that of the PTT–DTBT –based device (3.05%) without any processing additives or posttreatments. [ABSTRACT FROM AUTHOR]