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Mixed conductors-materials that can efficiently conduct both ionic and electronic species-are an important class of functional solids. Here we demonstrate an organic nanocomposite that spontaneously forms when mixing an organic semiconductor with an ionic liquid and exhibits efficient room-temperature mixed conduction. We use a polymer known to form a semicrystalline microstructure to template ion intercalation into the side-chain domains of the crystallites, which leaves electronic transport pathways intact. Thus, the resulting material is ordered, exhibiting alternating layers of rigid semiconducting sheets and soft ion-conducting layers. This unique dual-network microstructure leads to a dynamic ionic/electronic nanocomposite with liquid-like ionic transport and highly mobile electronic charges. Using a combination of operando X-ray scattering and in situ spectroscopy, we confirm the ordered structure of the nanocomposite and uncover the mechanisms that give rise to efficient electron transport. These results provide fundamental insights into charge transport in organic semiconductors, as well as suggesting a pathway towards future improvements in these nanocomposites.

Organic semiconductors have emerged as an attractive class of materials for neuromorphic computing applications, particularly in crossbar arrays for artificial neural network (ANN) accelerators. Here, one of the last persistent challenges facing organic materials for adoption in these applications is addressed by developing a fabrication process capable of lithographically patterning vertical, three‐terminal electrochemical random‐access memories (ECRAMs). Central to the realization of this device architecture is the development of a hybrid electrolyte system: a porous inorganic matrix permeated with an ionic liquid, which enables vertical stacking of the organic semiconductor channel and gate. The resulting stacked hybrid organic/inorganic ECRAMs (SHOEs) exhibit superior dynamic range to comparable lateral devices (>2×), exceptional cycling endurance (>109 Write–Read Cycles), low energy switching (2.7 pJ), and can be fabricated with dimensions limited by lithographic resolution. The fabrication process developed allows for independent control over device channel, electrolyte, and gate dimensions, and by reducing channel lengths down to a single micron, the fabricated devices can operate (Write+Read) at >MHz speeds. Further, the hybrid electrolyte design provides an effective means to confine an ionic liquid for use in other electrolyte‐gated devices. [ABSTRACT FROM AUTHOR]