Research in IRG-1 in the UMN MRSEC has brought oxide electrochemical transistors to the verge of applications. Cycling endurance and switching speed are the two final roadblocks to realistic devices. In this period, a collaboration between IRG-1 and a Seed investigator has led to record cycling endurance in ion-gel transistors based on topotactic redox cycling of La0.5Sr0.5CoO3-d (LSCO), improving on previous records by an order of magnitude. LSCO is one of the premier materials for such transistors, as gate-induced oxygen vacancy formation induces a topotactic structure change due to ordering of oxygen vacancies. The IRG/Seed team applied operando FTIR spectroscopy to probe the optical response of ion-gel gated LSCO during voltage cycling, uncovering a wealth of new mechanistic understanding including about the roles of humidity, device geometry, and electrode metal selection. This enabled optimized devices operating over at least 100 cycles. This sustained modulation of optical properties in the infrared motivates the use of LSCO in thermal camouflage, thermoregulation, and several other applications.
