Interphase characterization at the n–CuInSe2/I−–I2 acidic electrolyte contact

Abstract

The chemical nature of a photoelectrochemically formed film at the n–CuInSe₂/I⁻–I₂–HI–Cu⁺ electrolyte interface is determined. Grazing incidence x‐ray diffraction reveals a phase consisting of polycrystalline CuISe₃ with elemental Se patches. Ultraviolet photoelectron spectroscopy (UPS) identifies the interphase as a p‐type semiconductor. Evidence for the film character of p–CuISe₃–Se⁰ is presented. Flat‐band potential, net acceptor density in the film, and the respective band bending in the substrate/film structure are determined assuming a n‐p junction between n–CuInSe₂ and p–CuISe₃–Se⁰. Electronic properties of the three‐phase junction substrate/film/electrolyte are deduced and the validity of the derived energy‐band diagram of the junction in contact is discussed.