Abstract
In organic mixed ionic–electronic conductors (OMIECs), it is critical to understand the motion of ions in the electrolyte and OMIEC. Generally, the focus is on the movement of net charge during gating, and the motion of neutral anion–cation pairs is seldom considered. Uptake of mobile ion pairs by the semiconductor before electrochemical gating (passive uptake) can be advantageous as this can improve device speed, and both ions can participate in charge compensation during gating. Here, such passive ion pair uptake in high-speed solid-state devices is demonstrated using an ion gel electrolyte. This is compared to a polymerized ionic liquid (PIL) electrolyte to understand how ion pair uptake affects device characteristics. Using X-ray photoelectron spectroscopy, the passive uptake of ion pairs from the ion gel into the OMIEC is detected, whereas no uptake is observed with a PIL electrolyte. This is corroborated by X-ray scattering, which reveals morphological changes to the OMIEC from the uptake of ion pairs. With in situ Raman, a reorganization of both anions and cations is then observed during gating. Finally, the speed and retention of OMIEC-based neuromorphic devices are tuned by controlling the freedom of charge motion in the electrolyte.
Original language | English (US) |
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Pages (from-to) | 2104301 |
Journal | Advanced Functional Materials |
DOIs | |
State | Published - Aug 21 2021 |
Bibliographical note
KAUST Repository Item: Exported on 2021-08-23Acknowledgements: The authors would like to kindly thank Ilaria Denti for helpful discussions regarding Raman spectroscopy. T.J.Q. and G.L. acknowledge support from the National Science Foundation Graduate Research Fellowship Program under grant DGE-1656518. A.S. gratefully acknowledges financial support from the National Science Foundation Award # DMR 1808401. A.M. gratefully acknowledges support from the Knut and Alice Wallenberg Foundation (KAW 2016.0494) for postdoctoral research at Stanford University. This work was in part performed at the Stanford Nano Shared Facilities (SNSF) and the nano@Stanford (SNF) labs, which are supported by the National Science Foundation as part of the National Nanotechnology Coordinated Infrastructure under award ECCS-1542152. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. A.S. and S.T.K. acknowledge financial support from the National Science Foundation and the Semiconductor Research Corporation, E2CDA Award #1739795. S.T.K. acknowledges the Stanford Graduate Fellowship fund for support. M.L.C., R.A.S., and D.R. gratefully acknowledge support from the U.S. Department of Energy Office of Basic Energy Sciences (DE-SC0016390) for PIL synthesis.
ASJC Scopus subject areas
- Biomaterials
- Electrochemistry
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics