Formation of all-oxide solar cells in atmospheric condition based on Cu2O thin-films grown through SILAR technique

Abstract

We report formation of Cu2O thin-films through successive ionic layer adsorption and reaction (SILAR) process. We have fully characterized the thin-films grown in atmospheric condition with a non-vacuum process. Post-deposition annealing in oxygen environment has led to formation of CuO thin-films. We have formed pn-junctions with a layer of the p-type copper oxides and another layer of n-type SnO2 nanoparticles. Such pn-junctions, along with other oxide semiconductors as carrier blocking layers acted as all-oxide thin-film solar cells which were formed in an atmospheric condition. We report the effect of NiO as a hole-transporting and electron-blocking layer and ZnO as a buffer layer between p- and n-layers to forbid chemical changes occurring at the interface. From scanning tunneling spectroscopy (STS) measurements we could locate band-edges of the materials with respect to their Fermi energy. The NiO/Cu2O/ZnO/SnO2 heterojunction devices having a staircase-like energy level led to facile transport of electrons and holes to the opposite electrodes and thereby acting as all-oxide thin-film solar cells yielding an energy conversion efficiency in excess to 1%.