PHOTOVOLTAIC PROPERTIES OF CDS/CDTE SOLAR-CELLS SINTERED WITH CDCL2

Transparent CdS films on glass substrates were prepared by coating with a CdS slurry which contained 10 wt% CdCl2 followed by sintering in nitrogen. All-polycrystalline CdS/CdTe solar cells have been fabricated by coating the CdS layer with a CdTe slurry, which contained various amounts of CdCl2, and sintering at 625°C for 1 h in nitrogen. The amount of CdCl2 was varied from 1 wt% to 10 wt%. The presence of CdCl2 is the CdTe layer before sintering improves the microstructures of the sintered CdTe layer and the junction. Both of these effects lead to improved solar cell efficiency. When the amount of CdCl2 is large, it causes a reduction in the hole concentration of the CdTe layer. This is presumably caused by chlorine doping and the formation of a thick layer of CdS1-xTex at the compositional interface which degrades the efficiency of the solar cell. A solar efficiency of 12.5% under 85 mw/cm2 of solar illumination was observed in a CdS/CdTe solar cell that was fabricated by coating a sintered CdS film with a CdTe slurry, which contained 4.5 wt% CdCl2, and by sintering the CdS-CdTe composite at 625°C in nitrogen.