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 In ₂O ₃ 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 In ₂O ₃ films is sufficient to form crystalline In ₂O ₃ 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 cm ² V ^-1 s ^-1, encasing these nanorods within a ZnO combustion precursor-derived matrix enhances the electron mobility to 0.2 cm ² 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.