New Angular-Shaped and Isomerically Pure Anthradithiophene with Lateral Aliphatic Side Chains for Conjugated Polymers: Synthesis, Characterization, and Implications for Solution-Prossessed Organic Field-Effect Transistors and Photovoltaics

An isomerically pure anti-anthradithiophene (aADT) arranged in an angular shape is developed. Formation of the framework of aADT incorporating four lateral alkyl substituents was accomplished by a one-pot benzannulation via multiple Suzuki coupling. This newly designed 2,8-stannylated aADT monomer was copolymerized with a ditheniodiketopyrrolopyrrole (DPP) unit and a bithiophene unit, respectively, to furnish an alternating donor–acceptor copolymer poly(anthradithiophene- alt -dithienyldiketopyrrolopyrrole) ( PaADTDPP ) and a thiophene-rich poly(anthradithiophene- alt -bithiophene) ( PaADTT ). PaADTT with crystalline nature achieved a high FET mobility of 7.9 × 10 –2 cm 2 V –1 s –1 with an on–off ratio of 1.1 × 10 7 . The photovoltaic device based on the PaADTDPP:PC 71 BM (1:2.5, w/w) blend exhibited a V oc of 0.66 V, a J sc of 9.49 mA/cm 2, and a FF of 58.4%, delivering a power conversion efficiency (PCE) of 3.66%. By adding 1.5 vol % 1-chloronaphthalene (CN) as a processing additive, the PCE can be improved to 4.24%. We demonstrated that these angular-shaped and alkylated aADT-based polymers have better organic photovoltaic (OPVs) and field-effect transistor (FETs) characteristics than the linear-shaped ADT-containing polymers.