Development of homogenous n-TiO2/ZnO bilayer/p-Cu2O heterostructure thin film

Metal oxide semiconductor materials have shown a great potential in the fabrication of heterojunction thin film due to its improved properties for photovolatic mechanism in solar cell application. In this work, p-(111)-Cu2O based heterostructure was successfully developed with uniformity and highly oriented n-TiO2/(002)-ZnO bilayer thin film in order to overcome improper electron mobility between the heterointerface of n and p-type layer by optimizing several properties. n-TiO2/ZnO bilayer acts as window layer deposited on FTO substrate by using sol–gel spin coating method. The crystallize size and transmittance spectrum of n-TiO2 thin film was improved after n-ZnO was coated onto TiO2 thin film. Meanwhile, cyclic voltammetry (CV) measurement was carried out and potential deposition of −0.4 V vs Ag/Cl at 40 °C was acquired. p-Cu2O which acts as absorbing layer was deposited onto n-TiO2/ZnO bilayer by using electrodeposition technique. The successful fabrication of n- TiO2/ZnO/p- Cu2O heterostructure were confirmed by the existence of all peaks on the XRD spectrum. Two strong absorption edges observed and the merged shape of p-Cu2O grain with other layer leads to the surface flatness improvement. The optical energies of n-TiO2/ZnO bilayer and p-Cu2O thin film are estimated as 3.15 and 1.75 eV, respectively. The structural, morphological, optical, and topological properties of thin films were characterized using X-ray diffraction, Field emission-scanning electron microscope, Ultraviolet–visible spectroscopy, and Atomic force microscopy, respectively.