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

## TL;DR

Researchers developed new polymers for organic transistors that can handle both positive and negative charges, enabling simpler logic circuits and biomedical applications.

## Contribution

The design of two new ambipolar conjugated polymers with balanced performance for organic electrochemical transistors.

## Key findings

- The polymers PDPPXO-2TzC4 achieved high and balanced ambipolar OECT performance with on-off ratios exceeding 10^5.
- Single-component inverters with ternary logic characteristics were fabricated using these polymers.
- The polymers showed good biocompatibility with human gingival fibroblasts.

## Abstract

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.

Two donor‐acceptor conjugated polymers, incorporating diketopyrrolopyrrole (DPP) and dialkoxybithiazole (2Tz) units with ethylene glycol (EG) side chains, exhibit relatively balanced ambipolar organic electrochemical transistor (OECT) performance. This ambipolarity enables the realization of single‐component complementary inverters capable of ternary logic. Moreover, these polymers demonstrate good biocompatibility with human gingival fibroblasts (HGF), supporting their potential in bioelectronics.