Pulsed Laser Deposition of Thin Film CdTe/CdS Solar Cells with CdS/ZnS Superlattice Windows

Pulsed Laser Deposition (PLD) is advantageous to the fabrication of superlattice structures and was applied to generate CdS(3nm)/ZnS(2nm) and CdS(6nm)/ZnS(4nm) superlattices within the CdS window layers of thin film CdTe/CdS solar cells to explore ways to improve the microstructure and transmittance of the window layer. At the same window layer thickness, the composite windows made with CdS/ZnS superlattices sandwiched with CdS layers have higher transmittance as compared to the single layer window of CdS. This resulted in enhanced short circuit current in the CdTe solar cells with the composite window as expected. Power conversion efficiency up to 5.2% has been obtained in CdTe (1.5 mu m) using this composite window. With optimization of the processing conditions, this composite window structure may provide a scheme to modify the window for better power-conversion efficiency in thin film CdTe solar cells.