PV characterization of CIGS2 thin film solar cells

CuIn/sub 1-x/Ga/sub x/S/sub 2/ (CIGS2) thin films were prepared by sulfurization of CuGa/In precursor on Mo-coated glass substrates in Ar:H/sub 2/S(4%) mixture at 475/spl deg/C. PV parameters of the best CIGS2 solar cells measured under AM 0 conditions at NASA GRC were as follows: V/sub oc/=739 mV, J/sub sc/=26.01 mA/cm/sup 2/, FF=63.7%, and /spl eta/=8.95%. Detailed current versus voltage and quantum efficiency analysis of /spl sim/9% (AM 0) efficient CIGS2 cells showed them to be normal, without serious limitations and some ways promising. Formation of a buried n/sup +/p homojunction probably due to Cd doping during CdS chemical bath deposition was inferred from enhancement of collection at low wavelengths under reverse bias. Such a junction is known to lead to high conversion efficiency. Values of series resistance Rs, shunt resistance Rp, diode factor A, and reverse saturation current Jo were /spl sim/0.6 /spl Omega/ cm/sup 2/, /spl sim/1160 /spl Omega/ cm/sup 2/, /spl sim/2.1 and /spl sim/2.6/spl times/168 A cm-2 respectively. Preparation of /spl sim/8% AM1.5 efficient CIGS2 thin-film solar cells on Mo-coated stainless steel foil substrates for ultra lightweight solar cells is described.