Abstract: A terminal functional side chain-substituted diketopyrrolopyrrole (DPP)-based terpolymer and a preparation method and use thereof is described herein. The terpolymer has the following structural formula: where R1 is a terminal siloxy-substituted swallow-tailed chain with 22 to 52 carbon atoms in total, and t1 and t2 each are an integer of 1 to 18; R2 is a semifluoroalkyl-substituted swallow-tailed chain with 12 to 60 carbon atoms in total and 10 to 46 fluorine atoms in total, t3 and t4 each are an integer of 1 to 16, and t5 and t6 each are an integer of 1 to 10; and Ar is any one selected from the group consisting of aryl, heteroaryl, substituent-containing aryl, and substituent-containing heteroaryl, and m and n each are an integer of 5 to 100.