Use of n-Type (Cu2Se)x(In2Se3)1-x Ordered Defect Chalcopyrite Films for Solar Cell Absorber Layers

The special attributes of CuIn3Se5 and related In-rich compounds from the (Cu2Se)x(In2Se3)1-x pseudobinary sytem are exploited for an absorber layer in a new thin-film photovoltaic cell. Single phase CuIn3Se5 films are synthesized by co-evaporation. Bi-layered n-type films from the (Cu2Se)x(In2Se3)1-x pseudobinary system with Cu-rich surfaces and 0.5..gtoreq..X..gtoreq..0.1, are synthesized bysequential deposition. An electrochemical approach, first developed for CuInSe2, is employed to construct n-(Cu2Se)x(In2Se3)1-x/p-CuISe3 heterojunctions. This approach leads to a remarkably uniform, clean np-heterointerface and a rough outer surface conducive to light trapping. EPMA, SIMS profiles and XRD analysis examine the (Cu2Se)x(In2Se3)1-x films and the CuISe3 overlayer. EBIC and I-Vanalyses investigate the formation of an electrically active n-CuIn3Se5/p-CuIse3 junction.