Lithium ion assisted hydration of metal ions in non-aqueous sol–gel inks for high performance metal oxide thin-film transistors

Abstract

The role of Li ions in lowering the dehydroxylation temperature of non-aqueous sol–gel inks for metal oxide thin film transistors (TFTs) was demonstrated for the first time. As a key mechanism in the lowering of the dehydroxylation temperature, the hydration of sol–gel inks by Li ions, which have a high charge density, was verified through various material analysis tools, such as Raman spectroscopy, TG-DTA, spectroscopic ellipsometry, XPS, and FT-IR. The hydration effect of Li ions on electronic properties was confirmed. This was done by evaluating the electrical properties of metal oxide TFTs that were fabricated at 300 °C using various kinds of sol–gel inks with and without Li ions. The results revealed that the dehydroxylation temperature was typically lowered by about 20 to 50 °C with the addition of Li ions to various kinds of non-aqueous sol–gel inks. Moreover, the Li-added metal oxide TFTs had mobilities that were several times higher than those of their undoped counterparts.