Spray deposited CuInS2/TiO2 thin film solar cells

Copper indium sulfide (CIS) solar cells with Ag/CIS/TiO₂/FTO/glass structure were fabricated by nonvacuum methods. The nanoporous TiO₂ and nanocrystalline CIS films were prepared by screen-printing and spray pyrolysis techniques, respectively. The obtained films were examined using field-emission scanning electron microscopy and X-ray diffraction. The solar cell properties were characterized under AM 1.5. The porous nature of TiO₂ layer was found to cause the formation of nanocrystalline CIS with a very small grain size within the TiO₂ matrix. The photocurrent could not be observed in any devices without a TiO₂ layer (i.e. CIS/FTO), while it was detected for the devices consisting of TiO₂ layer (i.e. CIS/TiO₂/FTO). The thickness of TiO₂ layer was optimized for maximum efficiency. The highest efficiency obtained solar cells was 2.3 × 10^-5 % (V_oc: 0.147 V, J_sc: 6.5×10^-7A/cm², FF: 0.24) with a 3-μm-thick TiO₂.