Photoelectrochemical Characterizations of CuInS2 and Cu(In,Ga)S2 Thin Films Fabricated by a Spray Pyrolysis Method

Polycrystalline CuInS2 chalcopyrite thin films were formed on a Mocoated glass substrate by annealing of a spray deposited precursor film in a sulfur atmosphere at 600 °C. Partial incorporation of Ga in the CuInS2 film with a Ga/In ratio of ca. 0.2 to form a Cu (In,Ga)S2 mixed crystal was also prepared. Photoelectrochemical (PEC) analyses revealed that the Ga incorporation was effective to modulate electric and semiconductive properties of the chalcopyrite film. As a result, relatively large cathodic photocurrent responses in PEC analyses as well as high photovoltaic properties of a solar cell based on the Cu (In,Ga)S2 film were obtained.