High-efficiency quadruple junction solar cells using OMVPE with inverted metamorphic device structures

We have produced a monolithically grown, two-terminal, series connected, quadruple junction III–V solar cell with a 1 sun AM0 conversion efficiency of 33.6%. The device epitaxial layers were grown using organometallic vapor phase epitaxy in an inverted order with a 1.91 eV GaInP subcell grown lattice-matched to a GaAs substrate followed by the growth of a lattice-matched 1.42 eV GaAs subcell, a metamorphic 1.02 eV GaInAs subcell, and a metamorphic 0.7 eV GaInAs subcell. This combination of bandgap energies is nearly ideal in that the current generation in each of the four subcells is nearly identical with absorption limited subcell thicknesses. We will discuss the motivation and development for a particular embodiment of the quadruple junction as well as the outlook for future improvements.