NREL researchers push past 1V CdTe cell barrier

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CdTe solar technology could be set to receive a major efficiency boost, with researchers from NREL, Washington State University and the University of Tennessee developing a new technique by which CdTe cells with increased open-circuit voltage can be produced.

The results were published yesterday in the scientific journal Nature Energy.

The key breakthrough was made by developing an alternative process for the cadmium chloride processing step. The NREL release sets out the new process:

"A small number of phosphorus atoms [were placed] on tellurium lattice sites and then carefully formed ideal interfaces between materials with different atomic spacing to complete the solar cell. This approach improved the CdTe conductivity and carrier lifetime each by orders of magnitude, thereby enabling the fabrication of CdTe solar cells with an open-circuit voltage breaking the 1-volt barrier for the first time."

The technique has allowed for CdTe cell formation in which open-circuit voltage exceeding the 750 to 850 millivolts ordinarily achieved by CdTe cells.

U.S. manufacturer and project developer First Solar is the leading CdTe solar producer, and has achieved 18.2% module efficiency. With a module output of between 2.8 to 2.9 GW in 2015, it is in the pole position to benefit to any major improvements made with CdTe semiconductor technology.

The research was funded under the U.S. Department of Energy’s SunShot Initiative.