Fabrication and characterization of Cu(InGa)Se[sub 2] solar cells with absorber bandgap from 1.0 to 1.5 eV

Abstract

Cu(InGa)Se 2 films were deposited by selenization of Cu/Ga/In precursor layers and by four source elemental evaporation. Characterization of films and devices is presented. The selenized films show that the process results in two phase films and the devices behave like CuInSe 2 devices. A high temperature anneal converts the films to single phase, resulting in an increased V oc . The Ga and In are uniformly incorporated in the evaporated Cu(InGa)Se 2 films and consequently V oc increases as the Ga content increases. However, the performance of the evaporated devices with high Ga are limited by voltage dependent current collection. The orientation of Mo and Cu(InGa)Se 2 films are found to be related but in this case there is no correlation between the film characterization and device behavior. Cu(InGa)Se 2 films with the relative orientation differing by two orders of magnitude give nearly identical device results.