Semiconductor poly(3,3"-didodecyl-quaterthiophene) (PQT-12) polymer for which the hole mobility exceeds 0.1 cm(2)/(V s) exhibits promising charge-transport characteristics as an organic thin-film transistor. A family of its oligomeric analogs, DDQT-n (3,3"-didedocylquaterthiophene-n) has been synthesized (with n = 1-6) and extensively characterized [Zhang, L.; et al. J. Am. Chem. Soc. 2013, 135, 844-854]. Through atomistic molecular dynamics and charge-transport simulations, we have studied the morphologies and electronic properties of crystalline didodecylquaterthiophenes (DDQT-1, DDQT-2, and DDQT-3). The morphologies are characterized by molecular ordering and paracrystallinity, while charge-transport is characterized by electronic-coupling, reorganization energy, energetic disorder, and hole mobility, calculated with VOTCA package. We observed increasing transport efficiency with increasing molecule size, as the morphologies evolve from oligomeric to polymeric packing arrangements. The trend is related to decreasing hole reorganization energy, energetic disorder, and increasing efficacy of transport topology. We also elucidate a direct link between molecular ordering and charge-carrier mobility of different DDQT-n oligomers.