Mixed Ionic–Electronic Conduction in Binary Polymer Nanoparticle Assemblies

Abstract

transistors. [5] Polymer-based MIECs contain two principal components, one for electronic conduction and the other for ionic conduction. Each of these components should meet the molecular packing requirements for charge transport and both components should arrange in cocontinuous morphologies with percolation pathways for charge transport in three dimensions. Yet, achieving such structures relevant for MIECs has not been straightforward. At present, several different strategies are used to design and fabricate MIECs. They are: (1) mixing of conjugated polymers and polyelectrolytes [e.g., poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)], [5,6,8,9] (2) imbibing ionic fluids in conjugated polymer films, [11] (3) incorporating ion conducting side chains on conjugated polymers, [12][13][14][15][16] (4) ion-doped [17][18][19][20] or oxidized [21] conjugated polymers, and (5) diblock copoly mer with ion conducting and electronic conducting polymers as the constituent blocks [e.g., poly(3-hexylthiophene)-bpoly(ethylene oxide) (P3HT-b-PEO)]. [2,3] However, these methods do not afford separate and systematic control over the morphology and properties of the ionic and electronic conducting phases while keeping the overall morphology constant. The central problem is the lack of a general approach to control the molecular packing and morphology in MIECs. We report here an approach, based on polymer nanoparticle selfassembly, to fabricate polymer-based MIECs. This approach provides a pathway to achieve tailored molecular order for each component on the nanoscale (<100 nm) and targeted assembly of the components on the mesoscale (>100 nm-100 µm). We demonstrate the efficacy of this approach for fabricating MIECs through binary nanoparticle assemblies of electronically conducting and Li-ion conducting polymer nanoparticles (see Figure 1a).Nanoparticle self-assembly is emerging as a powerful tool to design and fabricate mesoscale assemblies and interfaces. [22][23][24][25] For polymer-based materials, they provide a unique pathway to generate complex structures and co-assemblies under nonequilibrium processing conditions with macroscopic homogeneity and compositional flexibility. In this strategy, we first fabricate polymer components as nanoparticles, and then use them as building blocks for further assembly to create Polymer-based mixed ionic-electronic conductors (MIECs) are desired for both bulk and interfacial materials in next-generation energy storage and electronic devices. Polymer-based MIECs contain two principal components, one for electronic conduction and the other for ionic conduction. The central problem is the lack of a general approach to control the molecular packing and morphology of the constituent components that will afford the ability to easily tune transport properties. This study demonstrates the efficacy of a modular method based on polymer nanoparticle self-assembly to achieve MIECs with tunable conductivity. This work uses poly(3-hexylthiophene) nanoparticles as the electronic conductor and li...

Mini-Review: Mixed Ionic–Electronic Charge Carrier Localization and Transport in Hybrid Organic–Inorganic Nanomaterials

“…In the case that any of the electronic or ionic transport is mediated by the presence of a secondary pathway in a MIEC, generally associated to grain boundaries or depleted regions, as we discuss before, a second (or ) parallel combination connected in series with R e (or R i ), respectively, could be useful to fit the total impedance response, with associated pathway represented by a zig-zag line in Figure 2B (Huggins, 2002 ). In the recent literature, both the inclusion and exclusion of this second (or ) parallel combination in biphasic polymeric MIECs have been observed, depending mainly on the electronic- and ionic-conducting phase concentration or microstructural differences (Patel et al, 2012 ; Renna et al, 2017 ). In the particular case of hOI -MIECs, the second contribution (and probably a third contribution) to ionic or electronic transport could be present due to the mere existence of the organic–inorganic interphase, as shown in Figure 2C .…”

Ionic–Electronic Conductivity in Ternary Polymer/Reduced Graphene Oxide/Polyelectrolyte Nanocomposite Coatings for Potential Application in Energy Storage

“…Impedance spectroscopy was conducted to further study the electrical conductivity of the films with the aim to isolate ionic from electronic conductivity. The use of gold to make electrical contacts allowed the separation of ions from electrons with the change in applied frequency. , Figure a shows the Nyquist plot obtained for P­(BzMA- stat - n BA)/GO/LS (5 wt %) (Nyquist plots for other films are presented in Figure S7, Supporting Information). The negative imaginary y -axis ( Z ″) observed at high frequencies in the Nyquist plot can be ascribed to the magnetization of wires inside the cables (connecting the films to the potentiostat).…”

“…These studies highlight the complexity of mixed ionic–electronic conductivity in composites and the importance of carefully considering the intrinsic properties of the components when designing a hybrid composite. It is to be noted that isolating ionic from electronic conductivity in hybrid composites is not trivial and requires the combination of complex electrochemical techniques, typically involving the use of blocking electrodes (stainless steel and gold as ion blockers and Nafion as an electron blocker) during impedance measurements. ,− …”

Structure Control of a π-Conjugated Oligothiophene-Based Liquid Crystal for Enhanced Mixed Ion/Electron Transport Characteristics

“…More recently, the field of organic electronics which utilizes π-conjugated small molecules and polymers as electronic conductors has experienced tremendous growth. Compared to traditional silicon-based electronics, organic electronics offer advantages of low cost processability, mechanical flexibility, biocompatibility, and nearly limitless capacity to tailor the physical properties via facile chemical design. − Together with the expansion of the organic electronics field, there have been growing interests in developing organic materials such as polymeric − or liquid crystal (LC) systems , with mixed electronic/ionic conducting properties that couple the electronic conduction of the π-conjugated moieties with other ionic conduction moieties.…”

“…Given their enormous potential, understanding the structure–processing–transport relationships in organic mixed conductors are of keen scientific and technological interests. Until now, only a few structure–mixed conduction studies have been performed on organic mixed conductors, and most of them only focus on polymeric systems. − Understanding fundamental mixed conduction in conjugated polymers, however, is not straightforward due to the complex semicrystalline structures that make both structure characterization and simulation challenging . Compared to polymeric systems, LCs hold advantages of simple assembly and structural reorganization because of their intrinsic fluidity.…”