Direct-current piezoelectric nanogenerator based on p-Si/n-ZnO heterojunction

•DC piezoelectric nanogenerator with a heterojunction was demonstrated.•The p-Si/n-ZnO heterojunction exhibits obvious rectifying behavior.•Piezoelectric current about 1 nA was generated from a single nanogenerator.•Reverse connection and two devices parallel connection were tested.•It is a new type of nanogenerator using the silicon chip as a top electrode.

We have demonstrated a direct-current piezoelectric nanogenerator with a novel structure of p-Si/n-ZnO heterojunction. Low resistance p-type silicon chip, with a large number of nano-concaves on the surface, was utilized as a top electrode over the n-type ZnO nanorod arrays, forming a heterojunction nanogenerator. Piezoelectric current, with average singles about 1 nA, was generated from the heterojunction nanogenerator. Rectifying behavior of the p-Si/n-ZnO heterojunction in our piezoelectric nanogenerator was analyzed from the I–V curve and the energy band structure. Furthermore, output tests of reverse connection and two devices parallel connection clearly eliminate the effects from measurement system errors and confirms that the current is generated from the nanogenerator. Our research presents an approach to integrating a new type of nanogenerator using the silicon chip directly, without expensive Pt or Au coated on the electrode surfaces.