A study of vapor CdCl2 treatment by CSS in CdS/CdTe solar cells

We report the effect of CdCl2 vapor treatment on the photovoltaic parameters of CdS/CdTe solar cells. Vapor treatment allows combining CdCl2 exposure time and annealing in one step. In this alternative treatment, the CdS/CdTe substrates were treated with CdCl2 vapor in a close spaced sublimation (CSS) configuration. The substrate temperature and CdCl2 powder source temperature were 400 °C. The treatment was done by varying the treatment time (t) from 15 to 90 min. Such solar cells are examined by measuring their current density versus voltage (J–V) characteristics. The open-circuit voltage (Voc), short circuit current density (Jsc) and fill factor (FF) of our best cell, fabricated and normalized to the area of 1 cm2, were Voc = 663 mV, Jsc = 18.5 mA/cm2 and FF = 40%, respectively, corresponding to a total area conversion efficiency of η = 5%. In cells of minor area (0.1 cm2) efficiencies of 8% have been obtained.