In this letter, we report externally confirmed total area efficiencies
reaching up to 12.9% for CdS/Cu(In,Ga)S2 based solar cells. These are the
highest externally confirmed efficiencies for such cells. The absorbers were
prepared from sputtered metals subsequently sulfurized using rapid thermal
processing in sulfur vapor. Structural, compositional, and electrical
properties of one of these champion cells are presented. The correlation
between the Ga distribution profile and solar cell properties is discussed
