A concise, highly efficient palladium-catalyzed direct CH (hetero)arylation is developed to modularly assemble a diketopyrrolopyrrole (DTDPP)-based polymer library to screen low-bandgap and near-infrared (NIR) absorbing materials. The DTDPP-based copolymers P1 and P2 with an alternating donoracceptordonoracceptor (DADA) sequence and the homopolymer P9 exhibit planarity and excellent -conjugation, which lead to low bandgaps (down to 1.22 eV) as well as strong and broad NIR absorption bands (up to 1000 nm).