Charge polarity-dependent ion-insertion asymmetry during electrochemical doping of an ambipolar π-conjugated polymer

Abstract

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.

VPERD Assessment of the Mechanical Property of Plasticizing Fully π‐Conjugated Polymers with Intrinsic Stretchability for Flexible Deep‐Blue Light‐Emitting Diodes

“…Emerging flexible electronic technologies play a pivotal role in enhancing the portability and intelligence of electronic devices, including electronic skin, wearable devices, flexible displays, intelligent sensing, and brain‐machine interfaces. [ 1–11 ] The intrinsic flexibility of functional nano‐layers is crucial for ensuring the robust optoelectronic properties and long‐term deformation operation stability of flexible devices subjected to continuous strain. [ 3,5,12–18 ] Hence, semiconductor polymers (SPs) with inherent flexibility emerge as ideal materials for functional layers in flexible optoelectronic devices, given their potential for interchain entanglement and interpenetration.…”

Sequential Doping of Carbon Nanotube Wrapped by Conjugated Polymer for Highly Conductive Platform and Thermoelectric Application

“…[20,21] Indeed, CPs doped with molecular dopants show a similar level of carrier density, but their mobility is significantly lower than that of conductive ceramics. [22][23][24] Therefore, the poor electrical conductivity of the doped CPs is attributed to their low mobility rather than their charge-carrier density.…”

Impact of Ionic Species on the Performance of Pedot:PSS‐Based Organic Electrochemical Transistors

“…As for different electrolyte compositions, Flagg et al, Cendra et al and Samuel et al have demonstrated that, in accumulationmode OECTs, electrolytes composed of small ions with higher hydration spheres tend to promote higher swelling. [25,26,28] Despite this, even with superior swelling, these electrolytes result in devices with lower performance and sensitivity. These results, at first glance, may seem contrary to the approach to increase the hydrophilicity of the polymer backbone and, therefore, counterintuitive, since greater hydration of the film should facilitate the ionic penetration and hence increase the volumetric capacitance.…”