Institute of Nanotechnology (INT)

Oxide semiconductors typically show superior device performance compared to amorphous silicon or organic counterparts, especially when they are physical vapor deposited. However, it is not easy to reproduce identical device characteristics when the oxide field-effect transistors (FETs) are solution-processed/printed; the level of complexity further intensifies with the need to print the passive elements as well. Here, we developed a protocol for designing the most electronically compatible electrode/channel interface based on the judicious material selection. Exploiting this newly developed fabrication schemes, we are now able to demonstrate high-performance all-printed FETs and logic circuits using amorphous indium-gallium-zinc oxide (a-IGZO) semiconductor, indium tin oxide (ITO) as electrodes, and composite solid polymer electrolyte as the gate insulator. Interestingly, all-printed FETs demonstrate an optimal electrical performance in terms of threshold voltages and device mobilit...

A focused ion beam (FIB) system is used to fabricate a micron-sized all-solid-state fluoride ion cell from a bulk battery for in situ transmission electron microscopy (TEM) testing. The bulk battery is based on a La0·9Ba0·1F2.9 solid-state electrolyte with a nanocomposite of Cu/C as a cathode and a nanocomposite of MgF2, Mg, La0·9Ba0·1F2.9 and C as an anode. The evolution of the morphology, structure, and composition of the electrodes and their interfaces with the electrolyte is characterized using in-situ TEM during electrochemical cycling. The high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy-energy dispersive X-ray (STEM-EDX) analysis of the cathode-electrolyte interface reveal the expected formation of CuF2 phase during charging. During cycling, grain growth of Cu in the cathode ingredients and Cu diffusion from the cathode into the electrolyte are observed in addition to void formation.

Lithium ion batteries (LIBs) are widely used for portable electronics. However, their application is limited because of energy density, safety issues, and the high cost. This necessitates a search for alternative battery technologies. Many alternative battery systems are currently investigated based on different chemistries, which include sodium, magnesium, chloride, aluminum, and potassium based batteries. Rechargeable batteries based on a fluoride anion shuttle are a promising alternative to Li-ion batteries with theoretical energy densities of more than 5000 WhL-1. However, detailed chemical and structural investigations are necessary to understand the structural changes and the degradation mechanisms to improve the performance of fluoride ion batteries. In the present thesis, TEM has been used to study all-solid-state fluoride ion batteries in situ and ex situ. For in situ TEM studies, two all-solid-state fluoride ion battery systems were used; a half-cell consisting of a Bi com...

Novel magnetoelectric core–shell ceramics exhibit characteristics of several traditional magnetoelectric composites and combine exceptional magnetoelectric coupling with low leakage current, high density and absence of substrate clamping effects.