Delayed Ignition of Autocatalytic Combustion Precursors: Low-Temperature Nanomaterial Binder Approach to Electronically Functional Oxide Films

Delayed ignition of combustion synthesis precursors can significantly lower metal oxide film formation temperatures. From bulk In₂O₃ precursor analysis, it is shown here that ignition temperatures can be lowered by as much as 150 °C. Thus, heat generation from ∼60 nm thick In₂O₃ films is sufficient to form crystalline In₂O₃ films at 150 °C. Furthermore, we show that the low processing temperatures of sufficiently thick combustion precursor films can be applied to the synthesis of metal oxide nanocomposite films from nanomaterials overcoated/impregnated with the appropriate combustion precursor. The resulting, electrically well-connected nanocomposites exhibit significant enhancements in charge-transport properties vs conventionally processed oxide films while maintaining desirable intrinsic electronic properties. For example, while ZnO nanorod-based thin-film transistors exhibit an electron mobility of 10^–3–10^–2 cm² V^–1 s^–1, encasing these nanorods within a ZnO combustion precursor-derived matrix enhances the electron mobility to 0.2 cm² V^–1 s^–1. Using commercially available ITO nanoparticles, the intrinsically high carrier concentration is preserved during nanocomposite film synthesis, and an ITO nanocomposite film processed at 150 °C exhibits a conductivity of ∼10 S cm^–1 without post-reductive processing.