Towards high efficiency electrodeposited CdS/CdTe thin film cells

Glass/ITO/CdS/CdTe/Cu-Au solar cells with efficiencies up to 13.1% were fabricated. The reasons for the high J/sub sc/ values, about 28 mA cm/sup -2/, are discussed. Current collection occurs at energies as high as 3.65 eV. Quantum spectral yield data at various voltages showed a high current collection efficiency and showed that loss mechanisms in the bulk were small compared with those at the interface. The density of interface states was greater than 10/sup 11/ eV/sup -1/ cm/sup -2/ and was the main factor reducing U/sub oc/ and the fill factor. Auger spectra showed that in the best cells the CdS layer did not spread much during processing. Photoluminescence data suggest that the material bandgap was lowered at the CdS/CdTe interface. Projected efficiencies of near 17% should be achievable.<
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