Researchers working with cadmium telluride (CdTe) solar cells have overcome a 60-year long practical limitation of the technology, as reported by Solar Daily.
Led by the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL), and in collaboration with Washington State University and the University of Tennessee, researchers were able to improve the maximum voltage available from CdTe solar cells. The work is published in the journal Nature Energy.
CdTe solar cells offer advantages over more common silicon solar cells, which currently comprise 90 percent of the market. CdTe cells can be manufactured for less money, have the lowest carbon footprint of any solar technology, and outperform silicon cells in the field.
However, CdTe cells have been limited by their maximum open-circuit voltage, which until now has been lower than that of silicon cells. Because of past limitations in CdTe materials, the maximum voltage that could be harvested from these solar cells was for six decades capped at 900 millivolts.
Researchers have now improved this performance metric by moving away from a processing step that used cadmium chloride, instead placing a small number of phosphorous atoms on telluride lattice sites, thereby forming an ideal interface between materials with different atomic spacing. The break through improved the conductivity and carrier lifetime of CdTe by orders of magnitude, and enabled the fabrication of CdTe solar cells with open-circuit voltages that surpass the 1-volt barrier.
Many researchers believe silicon-based solar cells have been improved nearly to their theoretical limit. This new advance in CdTe solar cell manufacturing opens up the way for even larger technological improvements of the material in the future. Key to the fabrication process was the purity and control achieved during the manufacturing process of the new CdTe solar cells.