Fabrication of CdS/CdTe solar cells with transparent p-type conductive SrCuSeF back contact

Transparent and p-type conductive SrCuSeF films were deposited by pulsed laser deposition (PLD) and their optical and electronic properties were characterized. The SrCuSeF films deposited at T-s >= 200 degrees C showed high transmittance of more than 50% in the visible light region (400< lambda < 800 nm). The band gaps of these SrCuSeF films were all about 2.8 eV. All the SrCuSeF films showed p-type conductivity. The conductivity and carrier concentration of the SrCuSeF films were a little smaller than those of BaCuSeF film. SrCuSeF films were applied to the back contact of CdS/CdTe solar cells. The solar cell with SrCuSeF back contact deposited at substrate temperature of 200 degrees C showed an efficiency of 10.3%. Then, the CdTe surface was etched in bromide-bromate solution before depositing the SrCuSeF back. We obtained the higher conversion efficiency of 11.6% (V-oc= 771 mV, J(sc)= 26.4 mA/cm(2), and FF= 0.570) for a solar cell with CdTe etched in the bromide-bromate solution.