High-Performance Ambipolar Organic Electrochemical Transistors Based on Diketopyrrolopyrrole-Dialkoxybithiazole Conjugated Polymers for Single-component Inverters

Single-component complementary inverters based on ambipolar organic mixed ionic-electronic conductors (OMIECs) offer promise for simplifying logic circuit design and fabrication. However, the mismatched ambipolar transport properties in OMIECs have hindered the realization of such devices. To address this challenge, we designed two ambipolar OMIECs with high-spin state: PDPPXO-2TzC4 (where X = 3, 5). These donor-acceptor (D-A) conjugated polymers were synthesized through the copolymerization of diketopyrrolopyrrole (DPP) and dialkoxybithiazole (2Tz) units, incorporating modified ethylene glycol side chains. Both materials demonstrated outstanding and relatively balanced ambipolar OECT performance, achieving an on-off ratio exceeding 10⁵ for both p/n-type operations. PDPP3O-2TzC4 achieved normalized maximum transconductances of 0.48 S cm^-1 (p-type) and 0.34 S cm^-1 (n-type), while PDPP5O-2TzC4 reached 0.42 S cm^-1 (p-type) and 0.29 S cm^-1 (n-type). They also exhibited rapid and well-matched p-type and n-type transient responses, with time constants (τ_on/off) of less than 5 ms. Furthermore, leveraging the relatively balanced ambipolarity of PDPPXO-2TzC4, we fabricated functional single-component complementary inverters and obtained ternary logic characteristics under specific V_DD. A biocompatibility assessment using human gingival fibroblasts (HGF) confirmed that PDPPXO-2TzC4 is suitable for biological applications, laying a foundation for future OECT devices based on these materials in logic circuits and biomedical fields.