Status and Potential of CdTe Solar-Cell Efficiency

The status of the highest efficiency CdTe solar cells is presented in the context of comparative loss analysis among the leading technologies for single- and polycrystalline photovoltaic materials. The Shockley-Queisser limit of a single-junction cell, with acknowledgement of variations from standard conditions, is used for reference. The highest CdTe currents achieved are comparable with the best single-crystal cells and superior to other thin-film cells. Voltages match those of multicrystalline Si, but lag behind those of CIGS and crystalline Si, and considerably lag behind crystalline GaAs. The potential for still higher CdTe efficiency will likely require a combination of reduced bulk recombination, smaller back-contact barriers, device structures with advantageous internal fields, and transparent emitters with minimal band offsets.