Effect of band offset on the open circuit voltage of heterojunction CuIn1-xGaxSe2 solar cells

The reasons behind why the theoretically estimated open circuit voltage (V-oc) of CuIn1-xGaxSe2 solar cells with large x values has not been realized are discussed. Typically, the reduction in V-oc is estimated only on the basis of the conduction-band offset between the absorber and the window material. The importance of the electron affinity difference between the window and the transparent electrode must also be taken into account. Based upon both of these factors, a material selection guideline is reported for the window and the transparent electrode layers suitable for high-x CuIn1-xGaxSe2 absorber-based solar cells. (C) 2004 American Institute of Physics.