Metal oxide heterojunctions using a printable nickel oxide ink

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Wide band gap metal oxides are crucial for inorganic optoelectronic applications.
• While zinc oxide is a common n-type material, developing suitable p-type oxides remains a challenge.
• There is a need for stable, conducting p-type oxide materials for advanced electronic devices.

Purpose of the Study:

• To formulate a stable and conducting p-type nickel oxide (NiO) nanofluid.
• To optimize the NiO nanofluid for extrusion-based direct writing.
• To investigate the properties of printed NiO/ZnO heterojunctions after annealing.

Main Methods:

• Synthesized NiO nanoparticles using a bottom-up wet chemical approach.
• Dispersed NiO nanoparticles in ethylene glycol to create a printable nanofluid.
• Optimized nanofluid viscosity and surface tension for direct writing.
• Printed NiO nanofluid onto aluminum-doped zinc oxide and annealed at various temperatures.

Main Results:

• The printed NiO nanofluid formed a heterojunction with aluminum-doped zinc oxide.
• The heterojunction exhibited rectifying behavior, with optimal performance at 250 °C annealing.
• The highest rectification ratio correlated with the lowest junction barrier height at 250 °C.
• Experimental results showed excellent agreement with theoretical predictions.

Conclusions:

• A stable, conducting p-type NiO nanofluid suitable for printing was successfully developed.
• The printed NiO/ZnO heterojunction demonstrates promising rectifying properties.
• This work facilitates the realization of oxide-based printed electronic devices.