Two new n-channel polymeric semiconductors for organic thin-film transistors (TFTs) based on electron-depleted perylene- (PDI) and naphthalene-dicarboxyimide (NDI) polymerized with dithiophene are reported: poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-naphthalene dicarboximide-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}, P(NDI2OD-T2), and poly{[N,N'-bis(2-octyldodecyl)-3,4,9,10-perylenedicarboximide-(1,7&1,6)-diyl]-alt-5,5'-(2,2'-bithiophene)}, P(PDI2OD-T2). Polymer regioregularity and electronic structure strongly depend on the rylene co-monomer. The use of NDI enables a regioregular and high-molecular-weight polymer with greatly stabilized electron transport in ambient. Unoptimized P(NDI2OD-T2)-based TFTs exhibit good electron mobilities [mu(e) = 0.04 (0.01) cm(2)/V.s in vacuum (ambient after 16 weeks) vs mu(e) = 0.003 (2 x 10(-4)) cm(2)/V.s in vacuum (ambient after 1.5 week) for P(PDI2OD-T2)] and on-off current modulation [I-on:I-off > 10(6)].