Tri-Acceptor Skeleton Balancing Ambipolar Mixed Ionic-Electronic Transport in Organic Conductors

Organic mixed ionic-electronic conductors (OMIECs) are emerging materials for low-power dissipation, high transconductance, and biocompatible semiconductor devices. To date, major efforts have been focused on p-type OMIECs, while ambipolar and electron-conducting counterparts remain underdeveloped. This disparity arises from the limited availability of robust conjugated skeletons capable of sustaining electrochemical reduction without compromising the electron transport pathways. In this work, we demonstrate a tri-acceptor skeleton comprising diketopyrrolopyrrole-benzothiadiazole-diketopyrrolopyrrole (DBD) units, which concurrently facilitates electrochemical oxidation and reduction processes. Additionally, we modulate side chain chemistry by halving the density of oligoethylene glycol (OEG) moieties. This two-dimensional (2D) tuning strategy achieves an optimal balance between ambipolar ionic and electronic transport properties, lowering the injection barrier for cations. hDBD-2FT exhibits high apparent product of mobility and volumetric capacitance (µC*), reaching 345.54 and 334.57 F cm^-1 V^-1 s^-1 for p-type and n-type conduction, respectively, demonstrating its potential for ambipolar mixed transport. Leveraging its efficient mixed transport, we successfully demonstrate complementary inverters and electrocardiogram monitoring applications. Our findings validate the efficacy of the 2D tuning strategy in balancing mixed transport properties and are anticipated to stimulate the development of OMIECs exhibiting higher performance metrics and power efficiency.