Preparation and characterization of CdS/CdTe thin film solar cells

Thin film n-CdS/p-CdTe heterojunctions for solar cells were prepared by chemical deposition of CdS and electrodeposition of CdTe layers. No chlorine was intentionally put into the deposition solution for CdTe preparation (the A samples), whereas chloride ions were added in the case of the B samples. No post-deposition treatment with CdCl2 followed. The structure and morphology of the cells were analyzed using X-ray diffraction and scanning electron microscopy. The photovoltaic properties were tested using illuminated current-voltage characteristics. The relationship between the structure and morphology of the CdTe layers and the efficiency of the cells was found, and it was confirmed that the presence of chloride ions was essential to achieve an efficiency of 9.4%. The contactless photovoltage (CFV) method was used to measure the minority carrier diffusion length in CdTe. Values of the diffusion length and some other parameters of lie cells were deduced by fitting the theoretical curve of the CPV spectral response to the experiment. (C) 1997 Elsevier Science S.A.