Chalcogenophene Comonomer Comparison in Small Band Gap Diketopyrrolopyrrole-Based Conjugated Polymers for High-Performing Field-Effect Transistors and Organic Solar Cells - Ashraf,RS; Meager,I; Nikolka,M; Kirkus,M; Planells,M; Schroeder,BC; Holliday,S; Hurhangee,M; Nielsen,CB; Sirringhaus,H; McCulloch,I (JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2015)