Solar Energy Materials and Solar Cells, Vol.55, No.1, 83-94, 1998
CuIn1-xGaxSe2-based photovoltaic cells from electrodeposited and chemical bath deposited precursors
We have fabricated 13.7%- and 7.3%-efficient CuIn1-xGaxSe2 (CIGS)-based devices from electrodeposited and chemical bath deposited precursors. As-deposited precursors are Cu-rich films and polycrystalline (grain size is very small) in nature. Only preliminary data is presented on chemical bath deposited precursors. Additional In, Ga, and Se were added to the precursor films by physical evaporation to adjust the final composition to CuIn1-xGaxSe2. Addition of In and Ga and also selenization at high temperature are very crucial to obtain high efficiency devices. Three devices with Ga/(In + Ga) ratios of 0.16, 0.26, and 0.39 were fabricated from electrodeposited precursors. The device fabricated from the chemical bath deposited precursor had a Ga/(In + Ga) ratio of 0.19. The films/devices have been characterized by inductive-coupled plasma spectrometry, Auger electron spectroscopy, X-ray diffraction, electron-probe microanalysis, current-voltage characteristics, capacitance-voltage, and spectral response. The compositional uniformity of the electrodeposited precursor films both in the vertical and horizontal directions were studied. The electrodeposited device parameters are compared with those of a 17.7% physical vapor deposited device.