Complementary circuits based on organic electrochemical transistors (OECTs) are attractive for the development of inexpensive and disposable point-ofcare bioelectronic devices. Ambipolar OECTs, which employ a single channel material, could decrease the fabrication complexity and manufacturing costs of such circuits. An ideal channel material for ambipolar OECTs should be electrochemically stable in aqueous environments, afford facile ion insertion for both cations and anions, and also facilitate high and balanced electron and hole transport. In this study, triethylene glycol functionalized diketopyrrolopyrrole (DPP)-based polymer is proposed for the development of ambipolar OECTs. It is shown that DPP-based OECTs have a high and comparable figure of merit for both n-and p-type operations. Logic NOT, NAND, and NOR operations with corresponding complementary circuits constructed from identical DPP-based OECT devices are demonstrated. This study is an important step toward the development of sophisticated complementary metal-oxidesemiconductor-like logic circuits using single-component OECTs.

Redox-active conjugated polymers are an emerging class of organic charge storage materials for lithium-ion batteries. The electron conducting conjugated backbone linking the localized redox moieties enables fast electron transfer kinetics. Polymers with redox moieties that have fast redox kinetics and high redox potentials with respect to Li + /Li while being stable under electrochemical environments are ideal for energy storage applications. In this work, we propose diketopyrrolopyrrole (DPP) as a suitable redox moiety for realizing redox-active conjugated polymer-based Li-ion cathodes. Li-ion batteries using DPP-based polymers proposed in this work show stable cycling up to 1000 cycles, a high rate performance with ∼70% capacity retention at a C-rate of 500 C, and reasonably high potentials of ∼2.2 V vs Li + /Li. We also demonstrate that these polymers could potentially find applications as cathode materials in other ion insertion batteries such as, for example, Na-ion batteries. The results of our work set an encouraging precedent for designing versatile, high energy density, and long-life charge storage materials based on DPP-based redox-active conjugated polymers.

The introduction of nonfullerene acceptors (NFA) facilitated the realization of high-efficiency organic solar cells (OSCs); however, OSCs suffer from relatively large losses in opencircuit voltage (V OC ) as compared to inorganic or perovskite solar cells. Further enhancement in power conversion efficiency requires an increase in V OC . In this work, we take advantage of the high dipole moment of twisted perylene-diimide (TPDI) as a nonfullerene acceptor (NFA) to enhance the V OC of OSCs. In multiple bulk heterojunction solar cells incorporating TPDI with three polymer donors (PTB7-Th, PM6 and PBDB-T), we observed a V OC enhancement by modifying the cathode with a polyethylenimine (PEIE) interlayer. We show that the dipolar interaction between the TPDI NFA and PEIE�enhanced by the general tendency of TPDI to form J-aggregates�plays a crucial role in reducing nonradiative voltage losses under a constant radiative limit of V OC . This is aided by comparative studies with PM6:Y6 bulk heterojunction solar cells. We hypothesize that incorporating NFAs with significant dipole moments is a feasible approach to improving the V OC of OSCs.

Organic materials are a sustainable alternative to replace inorganic transition metal-based cathodes in rechargeable intercalation batteries. Among the possible redox active organic materials, conjugated polymers with multiple redox sites per repeat unit are expected to afford high energy and power densities while being resistant to dissolution when in contact with battery electrolytes. However, accessing the full capacity of polymeric electrodes while ensuring electrochemical reversibility has been challenging. Using diketopyrrolopyrrole (DPP)-based donor− acceptor (D−A) polymers as model systems and complementary electrochemical experiments and first-principles calculations, we show that conjugated backbone moieties that minimize charge localization on the electron accepting repeat units lead to near theoretical discharge capacities. Further, the capacity enhancement is associated with better rate performance and improved electrochemical stability of the polymer over prolonged cycling. Our work suggests that charge density on the electron accepting moiety is a potential descriptor for rationally designing redox-active polymer electrodes that afford high discharge capacities along with a long cycle life.

Electrochemical doping is central to a host of important applications such as bio-sensing, neuromorphic computing and charge storage. However, the mechanisms that enable electrochemical dopability and the various parameters that control doping efficiencies are poorly understood. Here, employing complementary electrochemical and spectroelectrochemical measurements, we report a charge-polarity dependent ion insertion asymmetry in a diketopyrrolopyrrole-based ambipolar π-conjugated polymer. We argue that electrostatic interactions are insufficient to fully account for the observed charge-specific ion insertion into the polymer matrix. Using polymer side-chain dependent electrochemical doping studies, we show that electron density donating and accepting tendencies of polymer side-chains sufficiently describe the observed charge-polarity dependent electrochemical doping. Our observations are akin to the solvation of dopant ions by polymer side-chains. We propose that Gutmann donor/acceptor number framework qualifies the ‘solvent-like’ properties of polymer side-chains and provides a rational basis for designing π-conjugated polymers with favorable mixed ionic electronic transport properties.