Preparation of Cu(In1−xAlx)Se2 thin films by sol-gel method

Polycrystalline Cu(In_1-xAl_x)Se₂ (CIAS) thin films with chalcopyrite structure were synthesized by sol-gel spin-coating method using nitrates as precursor for low-cost photovoltaic applications. Sequential reduction and selenization treatments were performed with hydrogen and Se vapor, respectively. X-ray diffraction (XRD), SEM, EDS and UV-visible spectrophotometer analysis have been employed to examine the structural properties, surface morphology, atomic concentrations and band gaps of polycrystalline CIAS thin films. The experimental results demonstrated that the Cu(In_1-xAl_x)Se₂ had good crystallinity, uniformity and stoichiometric composition. Simultaneously, we discussed the phenomenon and mechanism of the two-layered structure formation of the synthesized Cu(In_1-xAl_x)Se₂ thin film.