Influence of CdCl2 activation treatment on ultra-thin Cd1-xZnxS/CdTe solar cells

Ultra-thin CdTe photovoltaic (PV) solar cells with an absorber thickness of 0.5 µm were produced by molecular organic chemical vapour deposition (MOCVD) onto indium tin oxide (ITO) coated boroaluminosilicate glass. A wide band gap Cd1-xZnxS alloy window layer was employed to improve spectral response in the blue region of the solar spectrum. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to monitor changes in the chemical composition and crystal structure of the Cd1-xZnxS/CdTe solar cell after varying the post-deposition CdCl2 activation treatment time and annealing temperature. The CdCl2 treatment leached Zn from the Cd1-xZnxS layer causing a redshift in the spectral response onset of absorption. S diffusion occurred across the Cd1-xZnxS/CdTe interface, which was more pronounced as the CdCl2 treatment was increased. A CdTe1-ySy phase was formed at the interface, which thickened with CdCl2 treatment time. Small concentrations of S (up to 2 at.%) were observed throughout the CdTe layer as the degree of CdCl2 treatment was increased. Greater S diffusion across the Cd1-xZnxS/CdTe interface caused the device Voc to increase. The higher Voc is attributed to enhanced strain relaxation and associated reduction of defects in the interface region.

CLAYTON Andrew;  BAKER M.A.;  BABAR S.;  GIBSON Peter;  IRVINE S. J. C.;  KARTOPU G.;  LAMB D. A.;  BARRIOZ V.; 

2015-08-26

ELSEVIER SCIENCE SA

JRC90094

0040-6090,   

http://www.sciencedirect.com/science/article/pii/S0040609015007476,    https://publications.jrc.ec.europa.eu/repository/handle/JRC90094,   

10.1016/j.tsf.2015.07.077,