Fabrication of CuInS2 films from electrodeposited Cu In bilayers effects of preheat treatment on their structural, photoelectrochemical and solar cell properties

Polycrystalline CuInS2 films were fabricated by sulfurization of electrodeposited Cu and In metallic precursor films in a Cu rich composition at 520 1C in H2S 5 in Ar . Structural analyses revealed that the adherence of the thus formed CuInS2 film to the Mo substrate was strongly dependent on heating profiles of the Cu In bilayer film a CuInS2 film with poor adherence having many crevices was formed when the Cu In bilayer film was heated monotonously from room temperature to 520 1C in Ar within 25 min followed by sulfurization, whereas CuInS2 films with good adherence were obtained when the Cu In films were pretreated at 110 C in Ar for 10 60 min just before increasing the temperature up to 520 C for sulfurization. It was also clarified that the CuInS2 film obtained without 110 C pretreatment had pinholes inside the film, whereas the CuInS2 films formed after 110 C pretreatment showed no notable pinholes. Photoelectrochemical responses of these CuInS2 films in an electrolyte solution containing Eu III indicated that the CuInS2 films obtained after 110 1C pretreatment had higher external quantum efficiency EQE values than those of films obtained without 110 1C pretreatment, mainly due to better adherence of 110 1C pretreated CuInS2 films to the Mo substrate than the CuInS2 film obtained without 110 1C pretreatment. The performance of solar cells with an Al ZnO Zn S,O CdS CuInS2 Mo structure also depended on the structural characteristics of the CuInS2 films, i.e., preliminary conversion efficiencies of ca. 5 were obtained for devices based on the CuInS2 films obtained after 110 C pretreatment, whereas the device prepared by the CuInS2 film without 110 C pretreatment showed the conversion efficiency less than 1.5