Cu(InAl)Se2 thin films and devices deposited by multisource evaporation

Cu(InAl)Se-2 is investigated as an alternative high bandgap alloy of CuInSe2 for achieving devices and modules with greater performance as bandgap and Voc increase. Device efficiencies with Cu(InGa)Se. and CuIn(SeS)(2) decrease for bandgap greater than 1.3 eV. In this work, Cu(InAl)Se-2 thin films were deposited by four-source elemental evaporation with a composition range of 0 less than or equal to Al/(In+Al) less than or equal to 0.65 corresponding to a bandgap range 1.0 less than or equal to E-g less than or equal to 1.8 eV. All films are single phase as determined by X-ray diffraction. Characterization of optical and structural properties of the films shows that the effect of increasing AI content on bandgap and lattice spacing agrees with the results on Cu(InAl)Se-2 crystals and with calculated values. Solar cells with structure glass/Mo/Cu(InAl)Se-2/CdS/ZnO were fabricated. The best cells have 11% efficiency and V-oc increases with increasing AI content to greater than 0.7 V.