Synthesis and characterization of poly(Dithieno[3,2-b:2′,3′-d] pyrrole) Derivatives Containing Thiophene Moieties and Their Application to Organic Devices

A series of conjugated polymers (PDTP, PDTPT, PDTPTT) based on dithieno[3,2-b:2′,3′-d]pyrrole (DTP) containing branched side-chains is synthesized. The synthesized polymers show good solubility due to branched side-chains in the organic solvent in the absence of heat treatment. To increase the oxidation potential, unsubstituted thiophene units are introduced into the polymer backbone. The introduction of unsubstituted thiophene units increases the oxidation potential, elevates degradation temperature, and enhances electronic properties. The PDTPTT FETs show the highest charge-carrier mobility among the three polymers. These polymers are used as a donor material in bulk heterojunction solar cells, and the PDTPTT photovoltaic cells exhibit high performance. The introduction of unsubstituted thiophene units simultaneously increases oxidation potential, elevates degradation temperature, and enhances electronic properties. The PDTPTT FETs shows the highest charge-carrier mobility, and the PDTPTT photovoltaic cells record the highest performance, consistent with such superior field-effect mobility.