Minimizing Polymer Band Gap via Donor‐Acceptor Frameworks: Poly(dithieno[3,2‐ b :2′,3′‐ d ]pyrrole‐ alt ‐thieno[3,4‐ b ]pyrazine)s as Illustrative Examples of Challenges and Misconceptions

Donor‐acceptor (D−A) frameworks have been produced via the copolymerization of the strong donor dithieno[3,2‐ b :2′,3′‐ d ]pyrrole (DTP) with ambipolar thieno[3,4‐ b ]pyrazine (TP) units to generate soluble, processible materials with band gaps as low as 0.8 eV. Optical and electronic characterization of the DTP‐TP copolymers illustrate common misconceptions in the relative contributions of the comonomers to the D‐A framework, as well as highlighting the challenges of minimizing band gap while also retaining desirable frontier orbital energies for application to technological devices.