Perylene diimides (PDIs) and their derivatives are excellent semiconductors, while conjugated polymers based on PDIs have limited applications because of their low electron mobility ((e)) derived from low molecular weight. The reported maximum number-average molecular weight (M-n) of related polymers is only 21 kDa because PDIs have very poor solubility due to strong - stacking of their big planar conjugated cores. Herein, it is found that suitable semi-perfluoroalkyl groups could enhance the solubility of PDIs significantly, and a series of semi-perfluoroalkyl modified conjugated polymers with high molecular weight and electron mobility were synthesized. The maximum M-n reaches 94.8 kDa [P(4C(F)8C(H)-PDI-T2)(HW)]. In their space-charge-limited current (SCLC) devices, all polymers exhibit typical characters of electron transporting semiconductors, and the highest (e) is up to 8.40 x 10(-3) cm(2)V(-1)s(-1) [P(4C(F)8C(H)-PDI-T2)(HW)], which is similar as that of widely used electron transporting semiconductor PC61BM (6.41 x 10(-3)cm(2)V(-1)s(-1)). (c) 2017 Wiley Periodicals, Inc.