Band discontinuity and bulk vs. interface recombination in CdS/CuInSe2 solar cells

A numerical model which shows the effects of conduction band discontinuity, Delta _cb, in CdS/CuInSe₂ solar cells is presented. Two scenarios for the dominant mechanism controlling open-circuit voltage, V_oc, are considered: CuInSe₂ bulk recombination and CdS/CuInSe₂ interface recombination. The computation shows that the short-circuit current is independent of Delta _cb for either scenario, while V_oc is strongly affected only for the interface-dominated case and only for the CuInSe₂ conduction band positive with respect to the CdS conduction band. The experimental evidence implies that interface domination is not always the case in real devices, if it occurs at all.