Monocrystalline silicon solar cell with silicon oxide-titanium nitride double-layer contact structure on back and preparation method thereof

The invention provides a monocrystalline silicon solar cell with a silicon oxide-titanium nitride double-layer contact structure on the back and a preparation method thereof. An n-type Si substrate is used as a base, an ultrathin a-SiOx (In) layer, an ITO film, a front silver electrode and a front aluminum electrode are arranged on the front surface of the substrate outwards in sequence, a back passivation structure is arranged on the back of the n-type Si substrate, the back passivation structure is a laminated passivation dielectric layer, the laminated passivation dielectric layer sequentially comprises an ultrathin SiOx film and a TiNy film from inside to outside, and an Al back electrode is arranged outside the back passivation structure; and a passivation contact layer of the back passivation contact monocrystalline silicon solar cell is located on the back face of the cell and comprises an ultrathin loose SiOx layer and a TiNy film. SiOx in the passivation structure is prepared through nitric acid oxid