Selenophene π-Bridge Enables Balanced Ambipolar Transport in High-Performance Organic Electrochemical Transistors

Developing single-component ambipolar organic mixed ionic-electronic conductors (OMIECs) is crucial for realizing low-power complementary circuits and biosensors based on organic electrochemical transistors (OECTs). However, there is a shortage of high-performance single-component ambipolar OMIECs, along with the issue of performance mismatch between p-type and n-type. Here, we copolymerized diketopyrrolopyrrole with selenophene serving as the π-bridge to synthesize a new ambipolar polymer, P(gTDPPSe). The selenophene π-bridge endows the polymer with favorable doping energy levels and a narrow bandgap, enabling P(gTDPPSe) to possess balanced ambipolar transport. Vertical OECTs of P(gTDPPSe) were fabricated, which demonstrate balanced and remarkable performance in both p-type and n-type modes, achieving peak transconductance of 192.9 and 117.6 mS, respectively. Notably, the peak I_ON of 57.3 mA (V_DS = -0.5 V, V_G = -1.0 V) in p-type mode is the highest among reported single-component ambipolar materials. Building upon this, the P(gTDPPSe)-based inverter achieved a maximum gain as high as 163 V/V. In this study, selenophene π-bridge enables precise control over molecular energy levels, planarity, and packing, yielding a high-performance balanced ambipolar copolymer. This presents a feasible approach to acquire balanced single-component ambipolar materials.