The present disclosure provides a multijunction solar cell that includes: a first sequence of layers of semiconductor material forming a first set of one or more solar subcells; a graded interlayer adjacent to said first sequence of layers; a second sequence of layers of semiconductor material forming a second set of one or more solar subcells; and a high band gap contact layer adjacent said second sequence of layers, wherein the high band gap contact layer is composed of p++ type InGaAlAs or InGaAs.