A set of engineered crystalline polymers containing thiazolo[5,4-d]thiazole and arene imides linked by ethynylene bridges have been modeled by means of density functional theory (periodic boundary) calculations. A large set of relevant electronic properties related to the optoelectronic and semiconductor character of these systems, such as optical band gap, frontier molecular orbital energy levels, electron affinity, ionization potential, reorganization energy, and electronic coupling between neighboring polymer chains, were obtained. We further discuss the effect of the ethynylene linkages, the presence of heteroatoms in thiazolo[5,4-d]thiazole rings, and the number of fused rings in the repeating unit on the electronic properties, for disclosing useful structure–property relationships. ; M.M. thanks the E2TPCYTEMA-SANTANDER program for the financial support.