Depth-dependent electronic band structure at the Au/CH₃NH₃PbI_3-xCl_x junction

The electronic properties of the interface between Au and organometallic triiodide perovskite (CH₃NH₃PbI_3-xCl_x) were investigated by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). CH₃NH₃PbI_3-xCl_x films were prepared on Au surfaces by spin casting with various concentrations to control the film thickness. Their morphology was examined by atomic force microscopy (AFM). CH₃NH₃PbI_3-xCl_x films exhibited a maximum valence band edge of 5.91 eV. The energy levels shifted downward by 0.26 eV with a perovskite coverage of 116.3 nm, indicating that band bending occurs at the interface. The observed energy level shift indicates an interface dipole at the Au/CH₃NH₃PbI_3-xCl_x junction. These findings contribute to the understanding of how perovskite materials function in electronic devices and aid in the design of new perovskite materials.