Proposal for superstructure based high efficiency photovoltaics

A novel class of cascade structures is proposed which features multijunction upper subcells. These will be referred to as superstructure high efficiency photovoltaics (SHEP). The additional junctions enhance spectral response and improve radiation tolerance by reducing bulk recombination losses. This is important because ternary III-V alloys, which tend to have short minority-carrier diffusion lengths, are the only viable materials for the high band-gap upper subcells required for cascade solar cells. Realistic simulations of AlGaAs SHEP's show that one sun AM0 efficiencies in excess of 26% are possible.