Lattice matchable alloy for solar cells

Abstract

An alloy composition for a subcell of a solar cell is provided that has a bandgap of at least 0.9 eV, namely, Ga 1−x In x N y As 1-y-z Sb z with a low antimony (Sb) content and with enhanced indium (In) content and enhanced nitrogen (N) content, achieving substantial lattice matching to GaAs and Ge substrates and providing both high short circuit currents and high open circuit voltages in GaInNAsSb subcells for multijunction solar cells. The composition ranges for Ga 1−x In x N y As 1-y-z Sb z are 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03.

1 - 9 . (canceled) 
     
     
         10 . A multijunction solar cell comprising:
 at least one subcell comprising Ga 1−x In x N y As 1-y-z Sb z , the at least one subcell having a low antimony (Sb) content, enhanced indium (In) content, and enhanced nitrogen (N) content, wherein the content levels are selected to achieve a bandgap of at least 0.9 eV, wherein the content values for x, y, and z are within compositions ranges as follows: 0.07≦x≦0.18, 0.025≦y≦0.04 and 0.001≦z≦0.03, wherein low corresponds to the content value for z and enhanced corresponds to the content value for x and for y.   
     
     
         11 . The multijunction solar cell according to  claim 10 , further comprising a substrate, and wherein the at least one Ga 1−x In x N y As 1-y-z Sb z  subcell is substantially lattice matched to the substrate. 
     
     
         12 . The multijunction solar cell according to  claim 11 , wherein the substrate is selected from the group consisting of GaAs and Ge. 
     
     
         13 . The multijunction solar cell according to  claim 10 , further comprising at least one additional subcell that is substantially lattice matched to the at least one Ga 1−x In x N y As 1-y-z Sb z  subcell. 
     
     
         14 . The multijunction solar cell according to  claim 11 , wherein the at least one Ga 1−x In x N y As 1-y-z Sb z  subcell has a lattice constant that is within 0.5% of the lattice constant of the substrate. 
     
     
         15 . The multijunction solar cell according to  claim 10 , wherein the at least one Ga 1−x In x N y As 1-y-z Sb z  subcell is configured to produce an open circuit voltage of at least 0.3 V under illumination of the multijunction solar cell at an intensity of 1,000 W/m 2  using the AM1.5D spectrum. 
     
     
         16 . The multijunction solar cell according to  claim 10 , wherein the at least one Ga 1−x In x N y As 1-y-z Sb z  subcell is not a current-limiting subcell upon illumination of the multijunction solar cell using the AM1.5D spectrum. 
     
     
         17 . The multijunction solar cell according to  claim 10 , wherein the content value for y is 0.03≦y≦0.04. 
     
     
         18 . The multijunction solar cell according to  claim 10 , wherein
 the content value for y is 0.03≦y≦0.04; and   the content value for x is 0.11≦x≦0.18.