Multilayer photovoltaic cell

Claim 1

A high efficiency, multijunction photovoltaic solar cell for use with a light concentrating element comprising: (a) a single crystal, single element substrate without an internal light sensitive junction, said substrate capable of lattice matching to within ±1% to a Ga 0 .88 In 0 .12 As semiconductor material responsive in the sun light range, (b) a first homogeneous layer of semiconductor material deposited on said substrate, lattice matched thereto and having about Ga 0 .88 In 0 .12 As composition with a semiconductor bandgap of 1.25 ev., and absorbing sun light energy at a first wavelength, (c) a second homogeneous layer of semiconductor material deposited on said first layer lattice matched to said first homogeneous layer and having about Ga 0 .69 In 0 .31 As 0 .5 P 0 .5 composition with a semiconductor bandgap of 1.5 ev., and absorbing sun light energy at a second wavelength, (d) a third homogeneous layer of semiconductor material deposited on said second layer lattice matched to said second homogeneous layer and having about In 0 .5 Ga 0 .5 P composition with a semiconductor bandgap of 1.85 ev., and absorbing visible light energy at a third wavelength, (e) said first, second and third layer each having essentially the same lattice constant as said single crystal substrate to within ±1%, (f) said first, second and third layer each containing a light sensitive p/n homojunction and each layer having a tunneling, shorting heterojunction with the layer immediately above and below it, (g) said first, second and third layers each developing essentially the same zero voltage light generated current as the other layers.