Direct Growth of a GaInP/GaAs/Si Triple-Junction Solar Cell with 22.3% AM1.5g Efficiency

III-V on Si multijunction solar cells exceede the efficiency limit of Si single-junction devices but are often challenged by expensive layer transfer techniques. Here, progress in the development of direct epitaxial growth for GaInP/GaAs/Si triple-junction solar cells is reported. III-V absorbers with a total thickness of 4.9 mu m are grown onto a Si bottom cell using metal organic vapor phase epitaxy. A new record efficiency of 22.3% under AM1.5g conditions is reached herein, outperforming the previous value of 19.7%. This improvement is possible through better nucleation conditions for the first GaP layer on Si and consequently the reduction of threading dislocations within the III-V absorbers from 1.4 x 10(8) to 2.2 x 10(7) cm(-2). Further efficiency improvements toward 30% require even lower threading dislocation densities in the order of 1 x 10(6) cm(-2), better light trapping in the Si bottom cell, and a reduction of parasitic absorption within the GaAsyP1-y graded buffer.