Green Synthesis of Diketopyrrolopyrrole- and Thiazolothiazole-Based Conjugated Polymers via Schiff-Base Condensation and Cyclization for Field-Effect Transistors

Conjugated polymers based on diketopyrrolopyrrole (DPP) and thiazolothiazole were synthesized from dialdehyde DPP and dithiooxamide via Schiff-base condensation and cyclization. The reaction utilizes only monomers and solvent, proceeding without any catalyst. The optical properties, molecular orbital energy levels, and microstructures were systematically investigated. Moreover, the synthesized conjugated polymers were evaluated as active layers in organic field-effect transistors, exhibiting a hole mobility of 0.06 cm2 V–1 s–1 with an Ion/Ioff ratio of 105. This work demonstrates that the Schiff-base condensation and cyclization approach has environmentally friendly characteristics and is applicable to the green synthesis of conjugated polymers.