Effect of alternating Cu poor/Cu rich/Cu poor/Cu rich/ layers of metal naphthenates in the growth process on the properties of CuInSe2 thin films prepared by the spin coating technique

To investigate the effect of alternating Cu poor/Cu rich/Cu poor/Cu rich/ layers in Cu–In precursors on the properties of the absorber, CuInSe2 polycrystalline thin films were prepared on glass substrates using the spin coating technique by thermal decomposition in N2 + H2 (10%) gas of Cu–In naphthenates and subsequent selenization in vacuum sealed ampoules of the obtained precursors with Se shots. Structure, crystal orientation and morphology of the obtained samples were studied by X-ray diffraction and scanning electron microscopy for different selenization temperatures. For the optical and electrical characterizations, photoluminescence and electrical conductivity measurements were also carried out. The deposited films were polycrystalline and showed a single phase with an intense (112) orientation for selenization temperature of 500 °C and time of 60 min. Alternating Cu poor/Cu rich/Cu poor/Cu rich/ layers of metal naphthenates in the precursors improved the optical and electrical properties of the CuInSe2 polycrystalline absorber layers. The principles of this procedure and the obtained results are detailed in this paper.