A π-conjugated polyazine containing diketopyrrolopyrrole (DPP) moiety, PDBTAZ, is synthesized through a simple condensation polymerization. PDBTAZ is found to be a high-performance ambipolar semiconductor in organic thin film transistors (OTFTs), showing an electron mobility of up to 0.41 cm² V⁻¹ s⁻¹ and a hole mobility of up to 0.36 cm² V⁻¹ s⁻¹.