Synthesis, characterization, and polymer solar cell and transistor application of a series of phenanthro[1,2-b:8,7-b]dithiophene-based donor-acceptor (D-A)-type semiconducting polymers combined with a diketopyrrolopyrrole unit are reported. The present polymers showed some unique features such as strong aggregation behavior, high thermal stability, and short - stacking distance (3.5-3.6 angstrom), which are suitable for high performance organic materials. In addition, they have a significantly extended absorption up to 1000 nm with a band gap of ca. 1.2 eV. However, such strong intermolecular interaction reduced their solubility and molecular weights, which resulted in low crystalline nature and moderate field-effect mobility of 0.01 cm(2) V-1 s(-1). Furthermore, such strong aggregation behavior led to the large-scale phase separation in the blend films, which may prevent the effective photocurrent generation, limiting J(sc) and power conversion efficiency of 2.0%. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 709-718